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Health-related physical fitness and its relationship to objectively measured physical activity in children McGuire, Karen Ashlee 2007-12-31

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H E A L T H - R E L A T E D P H Y S I C A L F I T N E S S A N D ITS R E L A T I O N S H I P T O O B J E C T I V E L Y M E A S U R E D PHYSICAL ACTIVIY IN CHILDREN  by  KAREN ASHLEE MCGUIRE B.Sc. Kinesiology, University o f Alberta  A THESIS SUBMITTED IN P A R T I A L F U L F I L L M E N T OF T H E REQUIREMENTS FORTHE D E G R E E OF  M A S T E R OF SCIENCE in THE F A C U L T Y OF G R A D U A T E STUDIES (Human Kinetics)  T H E UNIVERSITY OF BRITISH C O L U M B I A August 2007  © Karen Ashlee M c G u i r e , 2007  11  ABSTRACT During c h i l d h o o d , p h y s i c a l activity ( P A ) builds the foundation for a healthy body and is an important determinant of chronic d i s e a s e risk. R e c e n t reports indicate that children in C a n a d a d o not participate in sufficient a m o u n t s of P A for optimal health a n d well-being. Furthermore, certain ethnic g r o u p s m a y be at higher risk of d e v e l o p i n g chronic d i s e a s e d u e to extremely low levels of P A a n d p h y s i c a l fitness. Literature delineating the relationship b e t w e e n P A a n d health-related p h y s i c a l fitness in children is inconsistent a n d h a s b e e n inhibited by P A m e a s u r e m e n t tools. Objective m e a s u r e s of P A m a y o v e r c o m e m a n y of the limitations a s s o c i a t e d with other P A m e a s u r e m e n t tools. T h e p u r p o s e of this investigation w a s to objectively m e a s u r e habitual P A , e x a m i n e differences in P A a n d health-related p h y s i c a l fitness b e t w e e n A s i a n a n d C a u c a s i a n children, a n d d e t e r m i n e the relationship b e t w e e n P A a n d health-related physical fitness. O n e - h u n d r e d s e v e n t y b o y s (n = 79) and girls (n = 91) in g r a d e s 4 a n d 5 from five s c h o o l s in the G r e a t e r V a n c o u v e r R e g i o n participated. M e a s u r e s of b o d y composition (Body M a s s Index a n d w a i s t circumference), v a s c u l a r health (blood pressure), resting heart rate, m u s c u l o s k e l e t a l fitness (grip strength, s i t - a n d - r e a c h , curl-ups a n d push-ups) cardiorespiratory fitness ( L e g e r shuttle run) a n d habitual P A (via accelerometry) w e r e obtained o v e r a 1-week p e r i o d . R e s u l t s indicated that b o y s participated in 134 minutes a n d girls a c c u m u l a t e 114 minutes of moderate-to-vigorous p h y s i c a l activity ( M V P A ) per day. O n l y 3 0 minutes a n d 15 minutes per d a y w e r e a c c u m u l a t e d in bouts e x c e e d i n g 5 minutes in duration in b o y s a n d girls respectively. During the s c h o o l d a y the p e r c e n t a g e of time s p e n t in M V P A for r e c e s s , lunch hour a n d P h y s i c a l E d u c a t i o n c l a s s w a s 2 8 % , 3 5 % a n d 1 3 % in b o y s a n d 1 8 % , 2 7 % a n d 1 6 % in girls. C a u c a s i a n girls a c c u m u l a t e d more M V P A per d a y , h a d significantly higher counts per minute a n d h a d higher aerobic fitness than A s i a n girls (p<0.05). T h e r e w a s no significant difference in m u s c u l o s k e l e t a l fitness. C a u c a s i a n b o y s h a d significantly higher counts p e r minute, higher a e r o b i c fitness, a n d significantly higher m u s c u l o s k e l e t a l fitness s c o r e s (p<0.05) than A s i a n boys. P h y s i c a l activity did not significantly predict cardiorespiratory or m u s c u l o s k e l e t a l fitness in either b o y s or girls. T h i s investigation d e m o n s t r a t e d that p h y s i c a l activity during the s c h o o l d a y w a s low. C a u c a s i a n b o y s a n d girls obtained higher P A a n d fitness levels than A s i a n b o y s a n d girls. T h e s e findings s u g g e s t that all children m a y be at higher risk for health c o m p l i c a t i o n s a s s o c i a t e d with low levels of P A , e s p e c i a l l y t h o s e of A s i a n ethnicity.  TABLE OF CONTENTS ABSTRACT TABLE OF CONTENTS LIST O F T A B L E S LIST O F F I G U R E S ABBREVIATIONS O P E R A T I O N A L DEFINITIONS R E F E R E N C E S F O R O P E R A T I O N A L DEFINITIONS  \ vi i:  ACKNOWLEDGEMENTS  xi  CHAPTER I  Introduction  C H A P T E R II  Literature Review  2.1 P h y s i c a l Activity P a t t e r n s in C h i l d r e n 2.1.1 G e n e r a l P h y s i c a l Activity Patterns 2.1.2 G u i d e l i n e s for P h y s i c a l Activity 2.1.3 S u m m a r y 2.2 Ethnicity, P h y s i c a l Activity a n d P h y s i c a l F i t n e s s 2.2.1 Ethnic Differences in P h y s i c a l Activity 2.2.2 Ethnic Differences in H e a l t h - R e l a t e d P h y s i c a l F i t n e s s 2.2.3 S u m m a r y 2.3 P h y s i c a l Activity in R e l a t i o n to H e a l t h - R e l a t e d P h y s i c a l F i t n e s s 2.3.1 P h y s i c a l Activity a n d W e i g h t Status 2.3.2 P h y s i c a l Activity a n d V a s c u l a r Status 2.3.3 P h y s i c a l Activity a n d M u s c u l o s k e l e t a l F i t n e s s 2.3.4 P h y s i c a l Activity a n d Cardiorespiratory F i t n e s s 2.3.5 S u m m a r y . 2.4 Motor P e r f o r m a n c e in C h i l d h o o d 2.4.1 M u s c u l a r Strength a n d E n d u r a n c e 2.4.2 Cardiorespiratory F i t n e s s 2.4.3 Flexibility 2.4.4 S u m m a r y 2.5 A s s e s s i n g P h y s i c a l Activity 2.5.1 S e l f - R e p o r t 2.5.2 Direct O b s e r v a t i o n 2.5.3 Heart R a t e Monitoring 2.5.4 P e d o m e t e r s 2.5.5 Indirect Calorimetry 2.5.6 D o u b l y - L a b e l e d W a t e r 2.5.7 A c c e l e r o m e t r y 2.5.8 S u m m a r y C H A P T E R III Methodology 3.1 Participants 3.1.1 G e n e r a l Participant Characteristics 3.2 C a r d i o v a s c u l a r D i s e a s e R i s k A s s e s s m e n t s 3.2.1 Anthropometry  x  5 7 10 10 11 12 12 12 13 16 16 17 18 19 20 20 21 21 21 22 22 23 23 23 24 24 .25 26 26 26 27 27  iv 3.2.2 V a s c u l a r Health 27 3.2.3 M u s c u l o s k e l e t a l F i t n e s s 27 3.2.4 C a r d i o v a s c u l a r F i t n e s s 28 3.2.5 P h y s i c a l Activity 28 3.3 P r o c e d u r e 29 3.3.1 D a y 1: W e i g h t Status, V a s c u l a r Health a n d H e a l t h - R e l a t e d P h y s i c a l Fitness Measures 30 3.3.2 D a y 2 : Activity Monitor Distribution 31 3.3.3 D a y 7: Activity Monitor P i c k - U p 32 3.3.4 P h y s i c a l Activity D a t a R e d u c t i o n 32 3.3.5 Statistical A n a l y s i s 33 C H A P T E R IV Results 4.1 G e n e r a l S u b j e c t Characteristics 4.2 P h y s i c a l Activity Patterns 4 . 3 E t h n i c Differences in P h y s i c a l Activity a n d H e a l t h - R e l a t e d P h y s i c a l F i t n e s s 4.4 R e g r e s s i o n A n a l y s i s 4.5 Intraclass Correlation  36 36 37 38 39 40  CHAPTER V Discussion 43 5.1 P h y s i c a l Activity Patterns in Children 43 5.1.1 G e n e r a l P h y s i c a l Activity Patterns 43 5.1.2 G e n d e r Differences in P h y s i c a l Activity a n d H e a l t h - R e l a t e d P h y s i c a l Fitness 44 5.1.3 P h y s i c a l Activity G u i d e l i n e s 45 5.2 Ethnicity, P h y s i c a l Activity a n d P h y s i c a l F i t n e s s 47 5.2.1 E t h n i c Differences in P h y s i c a l Activity 47 5.2.2 Ethnic Differences in H e a l t h - R e l a t e d P h y s i c a l F i t n e s s 49 5.3 P h y s i c a l Activity a n d P h y s i c a l F i t n e s s 51 5.3.1 P h y s i c a l Activity a n d M u s c u l o s k e l e t a l F i t n e s s 51 5.3.2 P h y s i c a l Activity a n d Cardiorespiratory F i t n e s s 52 5.3.3 P h y s i c a l Activity a n d P h y s i c a l Fitness 53 5.3.4 P h y s i c a l Activity a n d W e i g h t Status 53 5.3.5 P h y s i c a l Activity in Relation to V a s c u l a r Health 54 5.4 Future Directions 55 5.5 Limitations 55 5.6 C o n c l u s i o n s 56  Footnotes  57  C H A P T E R VI APPENDICES  Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix  A B C D E F G H  References  58 70  70 83 87 88 89 90 92 94  V  Appendix 1 Appendix J Appendix K Appendix L  9 5 96 9 7 .110  VI  LIST OF TABLES T a b l e 2 . 1 . P h y s i c a l activity guidelines for children 8 T a b l e 2.2. P h y s i c a l activity a n d weight status 15 T a b l e 2.3. P h y s i c a l activity a n d cardiorespiratory fitness 19 T a b l e 3.1. C l a s s i f i c a t i o n of p h y s i c a l activity intensity 29 T a b l e 4 . 1 . Participant characteristics ^ 36 Table 4.2. Correlations 37 T a b l e 4 . 3 . P h y s i c a l activity o u t c o m e v a r i a b l e s 38 T a b l e 4.4. R e s u l t s of hierarchical multiple regression m o d e l for cardiorespiratory fitness in A s i a n a n d C a u c a s i a n girls 41 T a b l e 4 . 5 . R e s u l t s of hierarchical multiple r e g r e s s i o n m o d e l for m u s c u l o s k e l e t a l fitness in A s i a n a n d C a u c a s i a n girls 41 T a b l e 4.6. R e s u l t s of hierarchical multiple r e g r e s s i o n m o d e l for cardiorespiratory fitness in A s i a n a n d C a u c a s i a n b o y s 42 T a b l e 4.7. R e s u l t s of hierarchical multiple r e g r e s s i o n m o d e l for m u s c u l o s k e l e t a l fitness in A s i a n a n d C a u c a s i a n b o y s 42 T a b l e D.1 A v e r a g e ' o n ' a n d 'off times 89 T a b l e E.1 Health-related p h y s i c a l fitness a n d p h y s i c a l activity d a t a in girls 93 T a b l e E.2 Health-related p h y s i c a l fitness a n d p h y s i c a l activity d a t a in b o y s 94 T a b l e E.3 Health-related p h y s i c a l fitness data in children without p h y s i c a l activity d a t a 9 5 T a b l e K . 1 . T-tests performed b e t w e e n g e n d e r s 98 T a b l e K.2. A N O V A performed b e t w e e n girls with a n d without valid p h y s i c a l activity data 98 T a b l e K.3. A N O V A performed b e t w e e n boys with a n d without valid p h y s i c a l activity data 99 T a b l e K.4. A N O V A performed b e t w e e n s c h o o l s to d e t e r m i n e intraclass correlation 99 T a b l e K.5. A N C O V A u s e d to e x a m i n e differences b e t w e e n C a u c a s i a n a n d A s i a n b o y s 100 T a b l e K.6. A N C O V A u s e d to e x a m i n e differences b e t w e e n C a u c a s i a n a n d A s i a n girls 100 T a b l e K.7. P C A of m u s c u l o s k e l e t a l fitness c o m p o n e n t s in all children 101 T a b l e K.8. P C A factor loadings of m u s c u l o s k e l e t a l fitness c o m p o n e n t s in all children 101 T a b l e K.9. P C A of m u s c u l o s k e l e t a l fitness in girls 101 T a b l e K . 1 0 . P C A factor l o a d i n g s of m u s c u l o s k e l e t a l fitness c o m p o n e n t s in girls 101 T a b l e K . 1 1 . P C A of m u s c u l o s k e l e t a l fitness c o m p o n e n t s in b o y s 102 T a b l e K.12. P C A factor l o a d i n g s of m u s c u l o s k e l e t a l fitness c o m p o n e n t s 102 T a b l e K.13. P C A of fitness c o m p o n e n t s in all c h i l d r e n . . 102 T a b l e K.14. P C A factor l o a d i n g s of fitness c o m p o n e n t s in all children 102 T a b l e K . 1 5 . P C A of health-related p h y s i c a l fitness c o m p o n e n t s in all children 103 T a b l e K.16. P C A factor l o a d i n g s of health-related p h y s i c a l fitness c o m p o n e n t s in all children 103 T a b l e K.17. F o r w a r d s t e p w i s e r e g r e s s i o n of cardiorespiratory fitness in girls 103 T a b l e K.18. F o r w a r d s t e p w i s e r e g r e s s i o n of cardiorespiratory fitness in b o y s 104 T a b l e K.19. H i e r a r c h i c a l r e g r e s s i o n of health-related p h y s i c a l fitness c o m p o n e n t in boys 104 T a b l e K.20. Hierarchical r e g r e s s i o n of health-related p h y s i c a l fitness c o m p o n e n t in girls. T a b l e K . 2 1 . Hierarchical r e g r e s s i o n of p u s h - u p s in b o y s T a b l e K . 2 2 . H i e r a r c h i c a l r e g r e s s i o n of p u s h - u p s in girls  105 105 106  vii  Table K.23. Table K.24. Table K.25. Table K.26. Table K.27. Table K.28. Table K.29. Table K.30.  Hierarchical regression of curl-ups in boys Hierarchical regression of curl-ups in girls Hierarchical regression of sit-and-reach in boys Hierarchical regression of sit-and-reach in girls Hierarchical regression of grip strength in boys Hierarchical regression of grip strength in girls Hierarchical regression of systolic blood pressure in boys Hierarchical regression of systolic blood pressure in girls  106 107 107 108 108 109 109 110  viii  LIST OF FIGURES Figure 3 . 1 . S c h e m a t i c of testing procedure Figure 3.2 D a y 1: S c h e m a t i c outlining the testing procedure Figure 3.3. D e c i s i o n tree for data reduction  30 31 33  ix ABBREVIATIONS  AS! BC  Action Schools! BC  BMI  body mass index  BP  blood pressure  CSEP  Canadian Society for Exercise Physiology  CVD  cardiovascular disease  DBP  diastolic blood pressure  EE  energy expenditure  HR  heart rate  KKD  kilocalories per kilogram  MVPA  moderate-to-vigorous physical activity  PA  physical activity  PE  physical education  SBP  systolic blood pressure  SD  standard deviation  TEE  total energy expenditure  U.K.  United Kingdom  WC  waist circumference  O P E R A T I O N A L DEFINITIONS A c c e l e r o m e t e r : A d e v i c e worn o n the body that p r o v i d e s a n objective m e a s u r e m e n t of p h y s i c a l activity. It c o n s i s t s of p i e z o e l e c t r i c t e c h n o l o g y that w h e n a c c e l e r a t e d , emits a voltage that is proportional to the acceleration of the body. T h e resulting information provides health-related information about p h y s i c a l activity s u c h a s frequency, intensity a n d duration (1). A c t i o n S c h o o l s ! B C ( A S ! B C ) : A best-practice p h y s i c a l activity m o d e l d e s i g n e d to a s s i s t e l e m e n t a r y s c h o o l s in creating individualized action plans to promote healthy living. It p r o v i d e s r e s o u r c e s a n d r e c o m m e n d a t i o n s for the creation of individualized A c t i o n P l a n s that integrate p h y s i c a l activity a n d healthy eating into the s c h o o l e n v i r o n m e n t (for more information visit www.actionschoolsbc.ca). Active: H a v i n g a n a v e r a g e daily e n e r g y expenditure ( E E ) b e t w e e n 3.0 - 5.9 kilocalories per kilogram ( K K D ) of body weight. W a l k i n g for o n e hour per d a y would result in a n E E of approximately 3.0 K K D (2). Bouted Activity: A n y activity that is a c c u m u l a t e d in durations of 5 minutes or m o r e a n d is related specifically to original d a t a f r o m this d o c u m e n t . C a n a d i a n S o c i e t y for E x e r c i s e P h y s i o l o g y ( C S E P ) : A non-profit organization c o m p o s e d of p r o f e s s i o n a l s interested a n d involved in the scientific study of e x e r c i s e p h y s i o l o g y , e x e r c i s e biochemistry, fitness a n d health (for m o r e information visit w w w . c s e p . c a ) . C a r d i o v a s c u l a r / C a r d i o r e s p i r a t o r v Fitness: T h e ability to transport a n d u s e o x y g e n during p r o l o n g e d , s t r e n u o u s e x e r c i s e or work. It reflects the c o m b i n e d efficiency of the lungs, heart, v a s c u l a r s y s t e m a n d e x e r c i s i n g m u s c l e s in the transport a n d u s e of o x y g e n (3). Children: C h i l d r e n refer to b o y s a n d girls between the a g e s of 5 - 12. C o m p l i a n c e : T h e act of adhering to the physical activity g u i d e l i n e s set forth by a governing body. E p o c h : T h e time period o v e r w h i c h a c c e l e r o m e t e r counts are a v e r a g e d (4). Ethnicity: A term w h i c h represents a s h a r e d history, s e n s e of identity, g e o g r a p h y a n d cultural similarities a m o u n g individuals (5). Fractionalization: M e t h o d of s e g m e n t i n g the time spent at different intensities of physical activity.  H e a l t h - R e l a t e d P h y s i c a l F i t n e s s : T h e c o m p o n e n t s of p h y s i c a l fitness that are related to health status, including c a r d i o v a s c u l a r fitness, m u s c u l o s k e l e t a l fitness, body c o m p o s i t i o n a n d metabolism (3). Inactive: V a l u e s of a v e r a g e daily E E l e s s than 1.5 K K D . W a l k i n g for no more than o n e quarter hour w o u l d result in an E E less than 1.5 K K D (2). Kilocalorie: the quantity of heat required to raise the temperature of 1 kg (1 L) of water 1° C (specifically from 14.5 to 15.5° C ) (6). Moderately A c t i v e : H a v i n g a n a v e r a g e daily E E b e t w e e n 1.5 - 2.9 K K D . W a l k i n g for o n e half hour per d a y w o u l d result in a n E E of approximately 1.5 K K D (2). M u s c u l o s k e l e t a l F i t n e s s : T h e fitness of the m u s c u l o s k e l e t a l s y s t e m , e n c o m p a s s i n g m u s c u l a r strength, m u s c u l a r e n d u r a n c e , m u s c u l a r power, flexibility, b a c k fitness a n d b o n e health (3). P h y s i c a l Activity: A l l leisure a n d non-leisure body m o v e m e n t s resulting in a n i n c r e a s e d e n e r g y output f r o m the resting condition (3). P h y s i c a l F i t n e s s : A physiologic state of well-being that allows o n e to meet the d e m a n d s of daily living or that provides the b a s i s for sport p e r f o r m a n c e , or both (3). R a c e : A term w h i c h implies biological traits indicative of meaningful genetic similarities in a group of individuals (5). S p o r a d i c Activity: A n y activity d a t a that is a c c u m u l a t e d in durations lasting less than 5 minutes a n d is related specifically to original d a t a from this d o c u m e n t . T r a c k i n g : T h e m a i n t e n a n c e of relative rank or position within a group o v e r t i m e (i.e., t h o s e participating in the least a m o u n t of P A a s children will participate in the least a m o u n t of P A a s adults). A s a g e n e r a l g u i d e , correlations <0.30 are c o n s i d e r e d low; t h o s e b e t w e e n 0.30 a n d 0.60 a r e m o d e r a t e ; a n d those >0.60 are high (7).  R E F E R E N C E S FOR OPERATIONAL 1.  DEFINITIONS  Esliger D W , Copeland J L , Barnes J D , Tremblay M S . Standardizing and optimizing the u s e of a c c e l e r o m e t e r data for free-living p h y s i c a l activity monitoring. J o u r n a l of P h y s i c a l Activity a n d Health 2 0 0 5 ; 3 : 3 6 6 - 3 8 3 .  2.  C a m e r o n C , C r a i g C , P a o l i n S . L o c a l opportunities for p h y s i c a l activity a n d sport: trends f r o m 1 9 9 9 - 2 0 0 4 . In: P h y s i c a l Activity B e n c h m a r k s P r o g r a m ; 2 0 0 4 .  3.  Warburton D E R , W h i t n e y Nicol C , Bredin S S D . Health benefits of physical activity: the e v i d e n c e . C M A J 2 0 0 6 ; 174(6):801 - 8 0 9 .  4.  C h e n K Y , B a s s e t t J D R . T h e technology of a c c e l e r o m e t r y - b a s e d activity monitors: current a n d future. M e d S c i Sports E x e r c 2 0 0 5 ; 3 7 ( 1 1 ( S u p p l ) ) : S 4 9 0 - S 5 0 0 .  5.  T r e m b l a y M S , P e r e z C E , A r d e r n C I , B r y a n S N , K a t z m a r z y k P T . Obesity, overweight a n d ethnicity: Statistics C a n a d a ; 2 0 0 4 J u n e .  6.  M c A r d l e W , K a t c h F, K a t c h V . E s s e n t i a l s of E x e r c i s e P h y s i o l o g y . 2 e d . Baltimore, M a r y l a n d : Lippincott W i l l i a m s & W i l k i n s ; 2 0 0 0 .  7.  M a l i n a R M . P h y s i c a l activity a n d fitness: p a t h w a y s from childhood to adulthood. A m e r i c a n J o u r n a l of H u m a n Biology 2 0 0 1 ; 1 3 : 1 6 2 - 1 7 2 .  Xlll  ACKNOWLEDGEMENTS T h e r e are n u m e r o u s individuals w h o h a v e a s s i s t e d m e in v a r i o u s w a y s throughout the duration of my M a s t e r s a n d to w h o m I a m very thankful. I a p p r e c i a t e the p e r s o n a l and a c a d e m i c support from e a c h a n d e v e r y o n e . T o the C P R a n d L E A R N lab m e m b e r s , ( B e n , J e s s , D o m , L e s l i e , L i n d s a y , Shirley, M a r c , S t e p h , a n d Mika) I o w e a s p e c i a l t h a n k - y o u for the c o n s i d e r a b l e amount of moral support a n d friendship that w a s offered o v e r the past few y e a r s . I w o u l d like to sincerely thank my committee m e m b e r s , Dr. H e a t h e r M c K a y a n d Dr. P J N a y l o r for their a d v i c e a n d intellectual contributions to this investigation. I a m very thankful to A c t i o n S c h o o l s ! B C for allowing m e to be a part of s u c h a fantastic initiative a n d hope it continues to thrive a n d b e s u c c e s s f u l . I a l s o appreciate the support from the staff a n d students at the B o n e H e a l t h R e s e a r c h G r o u p throughout d a t a collection a n d d a t a a n a l y s i s . I a m e s p e c i a l l y grateful for the enthusiastic children w h o participated in the a c c e l e r o m e t r y portion of the A S ! B C initiative. T h e project w o u l d not h a v e b e e n c o m p l e t e d without their willing participation. I a m d e e p l y indebted to both D a l e E s l i g e r for his w i s d o m , time a n d patience, a n d his programmer, Eric Finlay w h o (with D a l e ' s help) provided m e with a n a m a z i n g program to optimize my a c c e l e r o m e t r y data. I would like to thank D y l a n , my family a n d friends for their continued support a n d e n c o u r a g e m e n t .  I must thank m y s u p e r v i s o r a n d c o -  supervisor, Dr. S h a n n o n B r e d i n a n d Dr. Darren W a r b u r t o n , for w e l c o m i n g m e into their laboratories, providing m e with e n d l e s s opportunities, a n d offering support a n d g u i d a n c e throughout the duration of the investigation.  1 CHAPTER I  Introduction Ninety-one percent of C a n a d i a n children are not meeting C a n a d a ' s P h y s i c a l Activity G u i d e l i n e s for C h i l d r e n a n d Y o u t h (8). T h i s is a n indication that m a n y of C a n a d i a n children are not physically active e n o u g h to maintain a n optimal health status (9). P h y s i c a l activity ( P A ) is required to maintain normal growth a n d d e v e l o p m e n t a n d health-related p h y s i c a l fitness (3) throughout c h i l d h o o d . Routine P A is a n effective primary a n d s e c o n d a r y preventive strategy against m a n y types of chronic d i s e a s e (3, 10). During c h i l d h o o d , P A builds the foundation for a healthy b o d y a n d c a n help to r e d u c e the o n s e t of risk factors a s s o c i a t e d with poor health (11-13). P h y s i c a l activity is a l s o a n important determinant of coronary heart d i s e a s e risk in youth (14) s u c h that risk d e c r e a s e s in a g r a d e d f a s h i o n a s P A level i n c r e a s e s (15). C l e a r l y , a physically active lifestyle is a n important c o m p o n e n t of a child's regular routine. In C a n a d a , e v i d e n c e indicates that certain ethnic g r o u p s a r e a c c u m u l a t i n g extremely low levels of regular P A (16-18). S t u d i e s h a v e reported that both A s i a n girls a n d boys participate in l e s s P A than a g e - m a t c h e d C a u c a s i a n p e e r s (17, 18). In Britain, investigations h a v e a l s o reported that A s i a n children h a v e lower cardiorespiratory fitness than their A n g l o - S a x o n counterparts (19). L o w l e v e l s of P A a n d low cardiorespiratory fitness a r e both a s s o c i a t e d with c a r d i o v a s c u l a r d i s e a s e risk (14) a n d s u g g e s t that children of A s i a n ethnicity m a y be a group m o r e vulnerable to ill health. It is therefore important that P A a n d fitness be e v a l u a t e d in children of different ethnic b a c k g r o u n d s to target preventative m e a s u r e s appropriately. Literature delineating the relationship of P A to c o m p o n e n t s of health-related p h y s i c a l fitness is inconsistent in children. T h e r e is a n increasing a m o u n t of e v i d e n c e demonstrating that body c o m p o s i t i o n is inversely related to habitual P A (20-22). N o relationship h a s b e e n reported b e t w e e n P A a n d v a s c u l a r status ( m e a s u r e d a s blood pressure) (14, 2 3 , 24). W e a k - t o - m o d e r a t e relationships h a v e b e e n detected b e t w e e n P A a n d m u s c u l o s k e l e t a l fitness (25, 26) a n d recent studies h a v e s h o w n significant positive relationships b e t w e e n P A a n d aerobic fitness (27-29). In adults, relationships b e t w e e n P A a n d c o m p o n e n t s of health-related p h y s i c a l fitness h a v e b e e n w e l l e s t a b l i s h e d w h e r e b y P A is a s s o c i a t e d with more f a v o u r a b l e o u t c o m e s (3, 30).  2  T o date, limitations a s s o c i a t e d with P A m e a s u r e m e n t tools h a v e inhibited the analysis of P A a n d health in children (15). T h e t e m p o of children's activity is o n e of rapid c h a n g e a n d is typically unstructured a n d s p o r a d i c in nature (31). T h e s e factors m a k e capturing activity difficult in this population. A s well, children h a v e less d e v e l o p e d cognitive skills than adults a n d are l e s s able to effectively u s e traditional methods of P A m e a s u r e m e n t s u c h a s self-report questionnaires (32). T h e r e f o r e , P A a s s e s s m e n t s for children must be improved to a d v a n c e r e s e a r c h in c h i l d h o o d P A (32) a n d its connection to health benefits. Objective m e a s u r e s of P A are able to o v e r c o m e m a n y of the limitations a s s o c i a t e d with various other P A m e a s u r e m e n t tools. T o accurately a s s e s s children's activity patterns, the e v a l u a t i v e instrument must be sensitive e n o u g h to detect, c o d e ; or record s p o r a d i c a n d intermittent activity (32, 33). T h e a c c e l e r o m e t e r is a unique and useful piece of t e c h n o l o g y that is able to capture a n d store activity patterns in small time intervals o v e r a period of d a y s or w e e k s . It c a n a l s o provide a m e a s u r e of important health-related d i m e n s i o n s of P A (frequency, intensity, duration). T h e s e a d v a n t a g e s m a k e the a c c e l e r o m e t e r a n ideal tool to u s e for the a s s e s s m e n t of P A in children, especially w h e n e x a m i n i n g relationships to health-related p h y s i c a l fitness or c a r d i o v a s c u l a r health. A c c o r d i n g l y , the p u r p o s e s of this investigation w e r e to obtain a n objective m e a s u r e of habitual P A in C a n a d i a n children, e x a m i n e the differences in P A a n d health-related physical fitness b e t w e e n A s i a n a n d C a u c a s i a n children, a n d determine the relationship b e t w e e n P A a n d health-related p h y s i c a l fitness. W e h y p o t h e s i z e d that: 1) T h e majority of children in the present investigation will not m e e t C a n a d a ' s P h y s i c a l Activity G u i d e l i n e s for C h i l d r e n a n d Y o u t h . T h i s h y p o t h e s i s is b a s e d o n reports f r o m H e a l t h C a n a d a stating that l e s s t h a n 5 0 % of children a c h i e v e optimal a m o u n t s of P A (9). 2) C a u c a s i a n children will h a v e higher P A levels t h a n A s i a n children living in the s a m e g e o g r a p h i c a l location a n d will a c h i e v e higher health-related p h y s i c a l fitness s c o r e s . T h i s is b a s e d o n current e v i d e n c e w h i c h indicates that individuals of A s i a n ethnicity are l e s s active than C a u c a s i a n individuals (16, 17, 34) a n d a c h i e v e lower s c o r e s on cardiorespiratory fitness tests (19). 3) C h i l d r e n that participate in m o r e moderate-to-vigorous p h y s i c a l activity ( M V P A ) per d a y will h a v e higher health-related p h y s i c a l fitness s c o r e s . T h i s hypothesis is  3 b a s e d o n previous literature reporting positive relationships b e t w e e n P A a n d various c o m p o n e n t s of health-related p h y s i c a l fitness (25, 2 6 , 29).  T h e present investigation w a s c o n d u c t e d in collaboration with A c t i o n S c h o o l s ! B C ( A S ! B C ) . T h i s initiative is a best practices P A m o d e l d e s i g n e d to a s s i s t elementary s c h o o l s in creating individualized s c h o o l action plans to promote healthy living. T h e vision of A S ! B C is to integrate P A into elementary s c h o o l s to a c h i e v e long-term, m e a s u r a b l e a n d s u s t a i n a b l e health benefits. T h i s is a c o m p r e h e n s i v e study that w a s being c o n d u c t e d in order to a s s e s s the health status of children in British C o l u m b i a a n d to determine w h e t h e r the A S ! B C m o d e l is a n effective m e a n s to positively c h a n g e s c h o o l environments, health-related behaviours a n d the health of children w h e n delivered a c r o s s g e o g r a p h i c a l l y d i v e r s e regions and cultures o v e r a three y e a r period. T h e participants of the P A (by accelerometry) c o m p o n e n t of the A S ! B C initiative w e r e a s u b - s a m p l e of 1459 students a n d included a multi-ethnic population of 579 children in g r a d e s 4 to 5 from s c h o o l s (n = 9) in the G r e a t e r V a n c o u v e r R e g i o n . M e a s u r e m e n t s w e r e collected throughout the s c h o o l y e a r from students enrolled in s c h o o l s participating in the A S ! B C initiative. A l l participants w e r e a part of the full evaluation c o m p o n e n t of the A S ! B C initiative w h i c h , in addition to the m e a s u r e s being taken for the p r o p o s e d investigation, included q u e s t i o n n a i r e s about family history, nutritional intake a n d k n o w l e d g e , P A participation, a n d p s y c h o - s o c i a l health. O n e hundred s e v e n t y children (79 b o y s ; 91 girls) from five s c h o o l s w e r e retained for this investigation. M e a s u r e m e n t s of body composition (body m a s s index a n d waist circumference), v a s c u l a r health (resting blood p r e s s u r e ) , resting heart rate, m u s c u l o s k e l e t a l fitness (grip strength, curl-ups, p u s h u p s , a n d sit-and-reach), c a r d i o v a s c u l a r fitness ( L e g e r shuttle run), a n d p h y s i c a l activity (accelerometry) w e r e obtained o v e r a 1-week p e r i o d . Following the Introduction, a R e v i e w of the Literature will b e p r e s e n t e d in C h a p t e r 2, w h i c h is relevant to the specific h y p o t h e s e s of the p r e s e n t investigation. A detailed M e t h o d o l o g y will b e p r e s e n t e d in C h a p t e r s 3, followed by the R e s u l t s a n d D i s c u s s i o n in C h a p t e r s 4 a n d 5, respectively. Finally, nine a p p e n d i c e s a r e i n c l u d e d ; A ) ethics forms for the investigation, B) H e a l t h History Q u e s t i o n n a i r e , C ) m u s c u l o s k e l e t a l fitness test protocols, D) a v e r a g e ' o n ' a n d 'off times u s e d to classify valid d a y s of accelerometry wear, E ) information s h e e t for parents and/or g u a r d i a n s of participants, F) Activity L o g ,  G ) s u m m a r y of o u t c o m e v a r i a b l e s in girls a n d b o y s , H) s u m m a r y of o u t c o m e variables in children without valid a c c e l e r o m e t r y d a t a , I) abstract entitled 'Capturing physical activity t e m p o in e l e m e n t a r y - s c h o o l - a g e d children, J) abstract entitled ' P h y s i c a l activity a n d a n t e c e d e n t s of c a r d i o v a s c u l a r d i s e a s e risk in children,' K) statistical a n a l y s e s , a n d L) raw data.  U p o n completion of this thesis, this d a t a will b e submitted for publication  in M e d i c i n e & S c i e n c e in S p o r t & E x e r c i s e a s three s e p a r a t e m a n u s c r i p t s .  5 C H A P T E R II Literature Review Throughout c h i l d h o o d P A is required to maintain normal growth a n d development, health-related p h y s i c a l fitness (3), a n d to establish lifestyle patterns that will reduce the risk factors for health c o m p l i c a t i o n s later in life (13). P h y s i c a l activity is a l s o a n important determinant of coronary heart d i s e a s e risk in youth (14) s u c h that risk d e c r e a s e s in a g r a d e d f a s h i o n a s P A level i n c r e a s e s (15). A physically active lifestyle is a n important c o m p o n e n t of children's regular routine a n d p l a y s a critical role in children's health.  In the following review, children's g e n e r a l activity patterns, physical  activity g u i d e l i n e s for children, ethnic differences in P A , a n d P A in relation to healthrelated fitness are d i s c u s s e d .  2.1 P h y s i c a l Activity P a t t e r n s in C h i l d r e n Children display unique P A patterns in w h i c h activity is highly transitory a n d is rarely s u s t a i n e d for periods greater than 10 minutes in duration (35). T h e r e are specific times of the d a y a n d d a y s of the w e e k in w h i c h activity is m o r e likely to b e o b s e r v e d in children (35, 36). A g e a n d g e n d e r are two factors consistently r e c o g n i z e d in the literature a s affecting P A levels in children (37, 38). A l t h o u g h there are n u m e r o u s guidelines currently a v a i l a b l e in w h i c h to a s s e s s P A in c h i l d r e n ; very few of the r e c o m m e n d a t i o n s are reflective of children's actual behaviour. A s s u c h , the purpose of this section is to e x a m i n e in further detail the g e n e r a l p h y s i c a l activity patterns of children, a s w e l l a s p h y s i c a l activity guidelines c o m m o n l y u s e d to a s s e s s P A in children.  2.1.1 G e n e r a l P h y s i c a l Activity Patterns T h e t e m p o of children's P A is o n e of rapid c h a n g e . Activities at all levels of intensity are highly transitory a n d h a v e a m e a n duration of 6 s e c o n d s a s determined by direct observation in children a g e s 6 - 1 0 y e a r s of a g e (31). C h i l d r e n ' s P A c o n s i s t s of short bursts of intense activities that are interspersed by brief intervals of low or m o d e r a t e intensity activity (31). H o o s et a l . (35) estimated that children ( a g e s 8 - 1 1 years) s p e n d approximately 1 9 % of their total active time on high intensity activities, s u c h a s playing or running outside, a n d o v e r half of their w a k i n g time in low intensity activities, s u c h a s playing c o m p u t e r g a m e s , e v e n though they c h a n g e activities a n d the level of intensity at  6  frequent intervals (31, 35). M o r e recently, B a q u e t et a l . (39) o b s e r v e d that children only spent approximately 1 0 % of their time in activities of m o d e r a t e intensity or greater a n d a m e r e 2 . 4 % of that time w a s s p e n t in vigorous activity (39). M o d e r a t e - t o - v i g o r o u s P A h a s b e e n m o s t c o m m o n l y o b s e r v e d during s c h o o l break times a n d s e e m s to b e l e s s prominent during the after-school hours(40) a n d during physical e d u c a t i o n ( P E ) l e s s o n s (40-42). S l e a p a n d W a r b u r t o n (40) h a v e s h o w n that only 31 % of children performed a s u s t a i n e d 5 minute bout of M V P A a n d e v e n fewer participated in a bout s u s t a i n e d for 10 minutes during P E l e s s o n s (40), a time w h e n it is a s s u m e d that children are a c h i e v i n g substantial a m o u n t s of quality e x e r c i s e . T h e amount of time a l l o c a t e d to P E in British C o l u m b i a for g r a d e s 4 a n d 5 students is o n a v e r a g e , 4 0 m i n u t e s three t i m e s per w e e k . It is e s t i m a t e d that during e a c h P E s e s s i o n , children is only likely to b e aerobically active for 6 % of the allotted 3 0 - 4 0 minutes of time (42). T h e r e c o m m e n d a t i o n s from the British C o l u m b i a Ministry of E d u c a t i o n are to s p e n d approximately o n e half of P E time ( 1 5 - 2 0 minutes) practicing activities that e n c o u r a g e active living a n d e n h a n c e health (43). T h i s e v i d e n c e s u g g e s t s that these guidelines are not being met. D e s p i t e participating in greater a m o u n t s of M V P A during r e c e s s than during P E , m o r e than 5 0 % of r e c e s s time is s p e n t in activities of light or sedentary intensity (44). A l t h o u g h children participate in m o r e activity during the s c h o o l d a y , the total a m o u n t of P A during that time period is still u n a c c e p t a b l y low. A l s o s o m e w h a t alarming is the finding that P A outside of s c h o o l h o u r s (40, 45) a n d o n w e e k e n d s w a s low (36, 46). S i n c e children s p e n d significantly m o r e time at h o m e than at s c h o o l this s u g g e s t s that children will e n g a g e in s e d e n t a r y activities more often unless the stimulus or opportunity to be active is a part of a regimented s c h e d u l e (40). Existing d a t a indicates that there m a y be substantial variation in P A levels in adults a n d children. P h y s i c a l activity monitored o v e r the c o u r s e of a w e e k m a y be p r e c i s e but m a y not represent u s u a l activity (47). In adults, a n y w h e r e from two to nine P A m e a s u r e s are r e c o m m e n d e d throughout the y e a r ( d e p e n d i n g o n the m e a s u r e m e n t tool) to obtain reliable m e a s u r e s of P A (47). Similarly, in children there is substantial instability in P A levels o v e r a o n e y e a r period a s m e a s u r e d by a c c e l e r o m e t r y e v e n with 6 or 7 d a y s of w e a r per collection time (48). K r i s t e n s e n et a l . (36) found that there w a s a significant variation in activity d e p e n d i n g on the d a y of the w e e k a n d month of the y e a r P A w a s m e a s u r e d in 8 to 10 y e a r old children . T h e greatest a m o u n t of intraindividual variation o c c u r r e d on the w e e k e n d s . During the winter m o n t h s (36, 48) or  7  during l e s s p l e a s a n t m o n t h s (49) l e s s activity w a s a c c u m u l a t e d . H o w e v e r , in a n environment without m a r k e d s e a s o n a l variability, s e a s o n a l i t y p l a y s a limited role in P A levels a n d a single m e a s u r e of P A is sufficient to estimate habitual activity levels (50). Significant g e n d e r differences are c o m m o n in P A levels. B o y s display higher levels of P A than girls of the s a m e a g e (11, 38, 51) a n d b o y s s p e n d significantly more time in vigorous P A than girls (11, 39, 52). B o y s a l s o participate in a greater number of longer bouts of higher intensity activity (39). R o w l a n d s et a l . (53) s u g g e s t e d that vigorous intensity P A m a y explain the differences in total activity b e t w e e n g e n d e r s . S l e a p a n d Warburton (40) found no difference in P A levels b e t w e e n b o y s a n d girls a g e d 5-11 y e a r s , h o w e v e r their findings s h o w e d that b o y s primarily p l a y e d g a m e s s u c h a s s o c c e r a n d girls w e r e m o r e likely to participate in g a m e s s u c h a s d a n c i n g , g y m n a s t i c s a n d netball. T h e r e is a trend for the total amount of P A to d e c l i n e in both g e n d e r s a s a function of a g e w h e r e b y girls s h o w a m o r e rapid d e c r e a s e in levels than b o y s (37, 38, 46). A d e c r e a s e in P A of 8 3 % from a g e 9 or 10 to a g e 18 or 19 h a s b e e n reported in girls (54). Part of this d e c l i n e in P A c a n be attributed to i n c r e a s e d d e m a n d s being p l a c e d on children throughout the e d u c a t i o n p r o c e s s , specifically with time spent sitting at s c h o o l a n d a m o u n t of h o m e w o r k g i v e n to b e c o m p l e t e d after s c h o o l (45). B e h a v i o u r a l r e s e a r c h h a s s u g g e s t e d that girls participate in l e s s P A than b o y s d u e to l e s s s o c i a l support from family m e m b e r s a n d friends, lower self-efficacy a n d activity c o m p e t e n c e s c o r e s , a n d l e s s enjoyment in sporting activities (55-57).  2.1.2 G u i d e l i n e s for P h y s i c a l Activity W h e n a s s e s s i n g P A patterns in children it is important to clearly define what 'being active' is (32) a n d to understand h o w P A is a c c u m u l a t e d in order to determine c o m p l i a n c e with a specific P A guideline (1). C o n c l u s i o n s regarding P A status are heavily d e p e n d e n t o n the P A guidelines s e l e c t e d to e x a m i n e the population of interest (58). T h e r e are currently n u m e r o u s variations of guidelines available a n d there is currently d e b a t e a s to w h i c h set is optimal for children (52) ( s e e T a b l e 2.1 for a description of the guidelines).  8 T a b l e 2 . 1 . D e s c r i p t i o n of p h y s i c a l activity g u i d e l i n e s for c h i l d r e n .  Source Health C a n a d a &  Guideline  Description  60 minutes of moderate activity and 30  Examples of moderate activity  Canadian Society for  minutes of vigorous activity each day.  are brisk walking and bike  Exercise Physiology  Accumulate activity in bouts of 5-10  riding.  minutes. Decrease sedentary activity by  Examples of vigorous activity  90 each day.  are running or playing soccer.  Healthy People 2010,  30 minutes of moderate activity on 5 or  Activity of an intensity of 3 or  goal 22.6  more days of the week. Accumulate in  more M E T s .  bouts of at least 1 minute. Healthy People 2010, goal 22.7  20 or more minutes of vigorous activity  Activity of an intensity of 6 or  that promotes the development of  more M E T s .  cardiorespiratory fitness on at least 3 days of the week United States  30-60 minutes of accumulated moderate  Moderate intensity activity on  intensity activity per day.  most or all days of the week.  International C o n s e n s u s  20 minutes of moderate-to-vigorous  Daily activity as part of lifestyle  Conference on Physical  activity at least 3 times per week in  activities.  Activity Guidelines for  addition to minimal amount of activity  Adolescents  (i.e. 30 minutes of moderate activity)  American College of  20-30 minutes of vigorous activity per  Recreational and fun aspects of  day.  activity should be emphasized.  60 minutes of activity that is at least  Activity of an intensity of 3 or  moderate intensity per day.  more M E T s on at least 5 days  Sports Medicine Opinion Statement United Kingdom Expert Consensus Group  per week.  T h e A m e r i c a n C o l l e g e of S p o r t s M e d i c i n e ( A C S M ) d e v e l o p e d t h e first f o r m a l g u i d e l i n e s for a d o l e s c e n t s a n d children b a s e d o n adult g u i d e l i n e s . T h i s o r g a n i z a t i o n r e c o m m e n d e d that c h i l d r e n a c h i e v e 2 0 - 3 0 m i n u t e s of v i g o r o u s e x e r c i s e e a c h d a y (59).  It is a s s u m e d , h o w e v e r , that the P A r e q u i r e m e n t s for o p t i m a l health in children a r e  different t h a n t h o s e n e e d e d by adults (32) b e c a u s e c h i l d r e n a r e l e s s p h y s i c a l l y d e v e l o p e d a n d typically d o not e n g a g e in the s a m e t y p e s of activity patterns (35).  For  e x a m p l e , a d u l t s a r e m o r e likely to participate in structured activities s u c h a s a 3 0 minute jog w h e r e a s c h i l d r e n are m o r e apt to e n g a g e in u n p l a n n e d g a m e s t h r o u g h o u t the d a y  (40). Investigations by S l e a p a n d Warburton (40) indicate that only 8 - 1 4 % of 5 - 11 year-old children regularly participate in a e r o b i c e x e r c i s e bouts that e x c e e d 10 minutes in duration. In contrast, A r m s t r o n g a n d W e l s m a n (46) d e t e r m i n e d (using heart rate monitoring) that 8 9 % of b o y s a n d 6 9 % of girls beginning s c h o o l a c h i e v e d o n e 10-minute bout of P A o v e r the m e a s u r e m e n t period of 3 d a y s . A l m o s t all children a c h i e v e d at least o n e 5-minute bout. S u s t a i n e d 2 0 minute bouts of either m o d e r a t e or vigorous activity w e r e rare in all a g e g r o u p s (46). A c c o r d i n g to this e v i d e n c e , a bout of activity prescribed to children s h o u l d b e no greater than 10 minutes in duration. Health C a n a d a a n d the C a n a d i a n S o c i e t y for E x e r c i s e P h y s i o l o g y ( C S E P ) created revised P A g u i d e l i n e s for children a n d youth in 2 0 0 2 (9) that a d d r e s s s o m e of the i s s u e s present in other g u i d e l i n e s . T h e s e guidelines state that children s h o u l d incorporate a n additional 6 0 minutes of m o d e r a t e P A a n d 30 minutes of v i g o r o u s P A into their current daily routines. C o n s i s t e n t with current r e s e a r c h , they r e c o m m e n d that the P A be a c c u m u l a t e d in b o u t s of 5 - 10 minutes throughout the d a y . T h e s e guidelines a l s o r e c o m m e n d that children d e c r e a s e their current amount of time s p e n t in sedentary activities by 90 minutes per day. T h i s r e c o m m e n d a t i o n is under the a s s u m p t i o n that children s p e n d m o r e than 90 minutes per d a y involved in s e d e n t a r y activities. T h e s e guidelines are b a s e d on expert opinion a n d are in a c c o r d a n c e with international guidelines w h i c h state that b e t w e e n 3.0 - 5.9 K K D n e e d to be e x p e n d e d daily to be c o n s i d e r e d active (2). T h e w i d e variation in g u i d e l i n e s u s e d to determine P A levels m a k e s obtaining the p r e v a l e n c e of c o m p l i a n c e in children extremely difficult. Furthermore, uncertainty in the a c c u r a c y of t h e s e m e a s u r e s is i n c r e a s e d d u e to the n u m e r o u s limitations a s s o c i a t e d with data acquisition of P A (58).  F o r e x a m p l e , P a t e et a l . (58) e x a m i n e d the  c o m p l i a n c e of students (grades 1-12) to three different P A g u i d e l i n e s : Healthy P e o p l e 2 0 1 0 , Objective 2 2 . 7 ; Healthy P e o p l e 2 0 1 0 , Objective 2 2 . 6 ; a n d United K i n g d o m Expert C o n s e n s u s G r o u p (refer b a c k to T a b l e 2.1). T h e p e r c e n t a g e of students meeting the specific criteria of the three guidelines w e r e < 3 % , 9 0 % a n d 6 9 . 3 % , respectively. U s i n g accelerometry, R i d d o c h et al. (38) found that virtually all 9 y e a r old children meet the United K i n g d o m Expert C o n s e n s u s G r o u p P A r e c o m m e n d a t i o n s a n d J a n z et a l . (60) a l s o found that m o s t children w e r e meeting the P A guidelines put out by the International C o n s e n s u s C o n f e r e n c e on P h y s i c a l Activity for A d o l e s c e n t s . C o n v e r s e l y , A r m s t r o n g et a l . (52) d e t e r m i n e d through heart-rate monitoring that m a n y children h a v e  adopted the s e d e n t a r y lifestyle that is a s s o c i a t e d with a d e c r e a s e in c a r d i o v a s c u l a r health a n d are therefore not participating in a c c e p t a b l e a m o u n t s of P A . T h i s clearly d e m o n s t r a t e s the c o n f u s i o n in the current literature a s s o c i a t e d with determining P A levels in children.  2.1.3 S u m m a r y C h i l d r e n ' s activity is typically intermittent a n d s p o r a d i c in nature b e t w e e n the a g e s of 5 - 1 1 y e a r s of a g e (31). It c o n s i s t s of short bursts of intense activity interspersed with intervals of low activity (31) a n d is quite variable o v e r a 1-year period (36, 48). Children are the m o s t active during s c h o o l break times (61) h o w e v e r recent e v i d e n c e indicates that activity during this time is still quite low (44). B o y s are consistently more active than girls (38, 51) a n d with a g e , there is a d e c r e a s e in activity levels (37, 38). T h e r e are n u m e r o u s guidelines available a n d there is currently d e b a t e a s to w h i c h provide children with the optimal amount of P A for positive health status. It has b e e n r e c o m m e n d e d that guidelines for children be tailored to their unique P A patterns (32). Determining the p r e v a l e n c e of P A in children is difficult d u e to the u s e of various guidelines. A c c o r d i n g l y , the first objective of this investigation w a s to m e a s u r e habitual P A a n d determine the p e r c e n t a g e of children meeting the C a n a d i a n P h y s i c a l Activity G u i d e l i n e s for C h i l d r e n a n d Y o u t h . T h e s e guidelines a r e currently the only o n e s available that are tailored specifically to the intermittent activity patterns in children. W e hypothesize that the majority of children will not meet t h e s e guidelines.  2.2 Ethnicity, P h y s i c a l Activity a n d P h y s i c a l F i t n e s s V a r i o u s reports indicate differences in unfavourable health b e h a v i o u r s between ethnic g r o u p s (16, 34). T h i s illustrates the n e e d to obtain m e a s u r e s of P A a n d fitness in a group of multicultural children. It is a l s o important to identify vulnerable g r o u p s at higher risk of d e v e l o p i n g chronic health complications for both p e r s o n a l a n d public benefits. In V a n c o u v e r there is a large population of A s i a n individuals however, the literature d e s c r i b i n g the difference in P A levels a n d health-related p h y s i c a l fitness b e t w e e n A s i a n a n d C a u c a s i a n children is s p a r s e . A v a i l a b l e d a t a d e m o n s t r a t e a l e s s f a v o u r a b l e health profile in A s i a n children c o m p a r e d to the C a u c a s i a n children (19, 62).  11 T h i s section will e x a m i n e the existing literature a n d c o m p a r e P A a n d fitness between C a u c a s i a n a n d A s i a n children.  2.2.1 Ethnic Differences in P h y s i c a l Activity D a t a d e s c r i b i n g differences in P A b e t w e e n C a u c a s i a n a n d A s i a n ethnic groups of all a g e s residing within the s a m e city are limited a n d reports are conflicting. Information obtained from the C a n a d i a n C o m m u n i t y Health S u r v e y (2000/01 a n d 2003) on adults indicated that the p r e v a l e n c e of P A w a s lowest in S o u t h a n d W e s t A s i a n g r o u p s a n d highest in C a u c a s i a n g r o u p s . S o u t h A s i a n g r o u p s are include E a s t Indian, P a k i s t a n i , a n d Sri L a n k a n , while W e s t A s i a n groups are includef A f g h a n a n d Iranian (16). Differences in P A b e t w e e n ethnic g r o u p s in youth h a v e b e e n detected but are not consistent a c r o s s studies. In a V a n c o u v e r - b a s e d investigation, M a c K e l v i e a n d c o l l e a g u e s (17) reported that 9 - 10 y e a r old C a u c a s i a n f e m a l e s participated in significantly m o r e l o a d e d P A (defined a s activity with a higher impact than walking) a n d considerably m o r e extracurricular sporting activities than a g e - m a t c h e d A s i a n girls. D a t a from the National Longitudinal S t u d y of A d o l e s c e n t Health in the United States s h o w e d that a substantial n u m b e r of A s i a n f e m a l e s (n = 9 2 2 , g r a d e s 7 -12) a c c u m u l a t e d l e s s than two 20-minute s e s s i o n s of M V P A per w e e k (34). C o n v e r s e l y , M c K a y et al. (18) found no difference in P A b e t w e e n A s i a n a n d C a u c a s i a n girls living in the s a m e g e o g r a p h i c a l location. Information from the National Longitudinal S t u d y of A d o l e s c e n t Health indicated that in a d o l e s c e n t s b o y s (n = 6 7 0 1 , g r a d e s 7 -12) the difference in P A b e t w e e n ethnic g r o u p s w a s present but s m a l l (63). M a c K e l v i e et a l . (64) reported no difference in P A b e t w e e n A s i a n a n d C a u c a s i a n b o y s . H o w e v e r , in a n earlier study c o n d u c t e d in V a n c o u v e r , significant differences in P A w e r e found. A s i a n b o y s w e r e 1 5 % less active than C a u c a s i a n p e e r s (18). Despite d i s c r e p a n c i e s b e t w e e n studies, there is a trend for C a u c a s i a n children to participate in m o r e P A than a g e - m a t c h e d A s i a n children. S i n c e the investigations in children utilized q u e s t i o n n a i r e s requiring activity recall, it is p o s s i b l e that P A is not accurately m e a s u r e d . With a l e s s subjective a n d more sensitive instrument to m e a s u r e P A , a more clearly defined trend m a y e m e r g e in both b o y s a n d girls. Furthermore, ethnic differences in P A h a v e b e e n reported to persist into adulthood (65) s u g g e s t i n g that in C a n a d a , the low levels of P A will continue throughout the lifespan u n l e s s  interventions are i m p l e m e n t e d . T h i s highlights the importance of further e x a m i n i n g the ethnic differences in P A .  2.2.2 Ethnic Differences in H e a l t h - R e l a t e d P h y s i c a l F i t n e s s Limited r e s e a r c h h a s b e e n c o n d u c t e d on the c o m p o n e n t s of health-related physical fitness ( m u s c u l o s k e l e t a l a n d cardiorespiratory fitness) a n d h o w they differ b e t w e e n A s i a n a n d C a u c a s i a n children living in the s a m e g e o g r a p h i c a l location. In the United K i n g d o m , lower l e v e l s of p h y s i c a l fitness in A s i a n a s c o m p a r e d to A n g l o - S a x o n children h a v e b e e n o b s e r v e d (66). C h i l d r e n of Indian (South A s i a n ) b a c k g r o u n d a c h i e v e d lower s c o r e s than children of other ethnicities in the cardiorespiratory, test (power output against load at 8 5 % of the m a x i m u m heart rate) utilized in the study (19). In previous investigations from our study group, it w a s d o c u m e n t e d that C a u c a s i a n children c o m p l e t e d m o r e l a p s in the 2 0 m L e g e r shuttle run test, indicating higher aerobic fitness, than A s i a n children (67). N o differences in weight status or v a s c u l a r health between ethnicities w e r e reported, however, the latter study d e m o n s t r a t e d a l e s s favourable c a r d i o v a s c u l a r health profile, a s m e a s u r e d by heart rate variability, in the A s i a n children (67). T h e trends w e r e the s a m e for b o y s a n d girls in both investigations.  2.2.3 S u m m a r y T h e r e is a trend for C a u c a s i a n children to participate in greater amounts of P A than a g e - a n d - s e x - m a t c h e d A s i a n p e e r s . In Britain a n d C a n a d a , A s i a n children are l e s s aerobically fit t h a n C a u c a s i a n children. H o w e v e r , for the m o s t part, no studies h a v e looked at the difference in m u s c u l o s k e l e t a l fitness b e t w e e n C a u c a s i a n a n d A s i a n children. In a multicultural city s u c h a s V a n c o u v e r , t h e s e o b s e r v a t i o n s warrant further investigation. A c c o r d i n g l y , the s e c o n d objective of this study w a s to e x a m i n e ethnic differences in P A levels a n d health-related p h y s i c a l fitness. W e h y p o t h e s i z e that C a u c a s i a n children will h a v e higher P A levels a n d will a c h i e v e higher health-related p h y s i c a l fitness s c o r e s t h a n A s i a n children.  2.3 P h y s i c a l Activity in R e l a t i o n to H e a l t h - R e l a t e d P h y s i c a l F i t n e s s P h y s i c a l activity a n d health-related p h y s i c a l fitness are i n d e p e n d e n t indicators of health status. In children, P A a n d c o m p o n e n t s of health-related fitness h a v e only a w e a k to m o d e r a t e relationship (7). T h i s is attributed to the difficulty in obtaining  13 m e a s u r e m e n t s in children, the variable nature of children's P A , normal growth a n d d e v e l o p m e n t , a n d the effect of s o c i a l , cultural, a n d e n v i r o n m e n t a l factors. T h e r e is k e e n interest in e s t a b l i s h i n g this relationship b e c a u s e r e s e a r c h s u g g e s t s that if P A a n d fitness are e s t a b l i s h e d in c h i l d h o o d , the active children will b e c o m e active adults and benefit from positive health o u t c o m e s (25). T h e following s e c t i o n reviews the current literature d e s c r i b i n g the relationships between P A a n d c o m p o n e n t s of health-related physical fitness.  2.3.1 P h y s i c a l Activity a n d W e i g h t S t a t u s B o d y m a s s index (BMI) a n d waist circumference ( W C ) are both well-established predictors of C V D risk factors a m o u n g children. B o d y m a s s index is thought to be a g o o d indicator of overall adiposity w h e r e a s W C is a n indicator of v i s c e r a l a d i p o s e tissue (68, 69). E v i d e n c e in adults indicates that W C c a n predict health risk b e y o n d that predicted by B M I a l o n e (69). In adults, risk for C V D i n c r e a s e s in a g r a d e d fashion with a m o v e from o n e B M I c a t e g o r y to the next BMI category. Within e a c h B M I category, those with a high W C h a v e a l e s s favourable c a r d i o v a s c u l a r profile t h a n t h o s e with a normal W C (70). E v e n though preliminary r e s e a r c h in children h a s demonstrated patterns similar to t h o s e of adults, the a d d e d v a r i a n c e a b o v e that predicted by BMI a l o n e or W C a l o n e w a s minimal a n d of no clinical significance ( 6 9 ) . In this investigation, B M I a n d W C w e r e first u s e d to predict risk factors for coronary artery d i s e a s e (blood lipids, g l u c o s e , a n d insulin levels) in children (n = 2 5 9 7 , a g e s 5 - 1 8 years). In the s e c o n d a n a l y s i s children w e r e stratified a c c o r d i n g to weight status a n d risk factors w e r e c o m p a r e d for g r o u p s with low a n d high W C v a l u e s (69). W e i g h t status a l s o r e m a i n s stable o v e r time. Indicators of obesity a n d a d i p o s e tissue distribution (BMI, W C , S u m of 5 Skinfolds) r e m a i n e d relatively constant a c r o s s a s e v e n - y e a r time s p a n in the C a n a d i a n population (14). In a four y e a r study in T e x a s the strongest predictor of B M I at the e n d of the study w a s B M I at the beginning of the study (71). T h i s d a t a implies that the risk factors a s s o c i a t e d with adiposity will a l s o track from childhood into adulthood a n d therefore, will predict adult C V D o u t c o m e s (72). T h u s , it is imperative to target children with preventative strategies and intervention initiatives to reduce the i n c i d e n c e of adult obesity a n d c a r d i o v a s c u l a r complications (73). With the u s e of m o r e objective P A m e a s u r e s , there is a n increasing amount of e v i d e n c e demonstrating that body composition, a s s e s s e d either by BMI or percentage  14  fat, is inversely correlated with habitual P A . C h i l d r e n in the top fertile of P A have statistically significantly lower B M I s c o r e s a n d lower p e r c e n t a g e b o d y fat than children in the lowest tertile of P A (20, 2 2 , 2 7 , 74) (see T a b l e 2.2). In a n international c o m p a r i s o n of overweight a n d P A in children, it w a s o b s e r v e d that the likelihood of being overweight w a s significantly lower in a d o s e - r e s p o n s e relationship with higher P A l e v e l s a s m e a s u r e d by self-report (74). Similar e v i d e n c e w a s d i s c o v e r e d in a c r o s s - s e c t i o n a l investigation b e t w e e n objectively m e a s u r e d P A a n d obesity m e a s u r e d a s fat m a s s ( a s s e s s e d by d u a l x-ray absorptiometry) a n d BMI (75). T h e r e is a trend for children w h o s p e n d the most time e n g a g e d in M V P A to have healthier b o d y c o m p o s i t i o n profiles than t h o s e children w h o s p e n d the least amount of time participating in M V P A (22, 76). D e n c k e r a n d c o l l e a g u e s (77) reported that it w a s time spent specifically in vigorous activity a n d not m o d e r a t e activity that w a s linked to low obesity status. T h e relation b e t w e e n body composition a n d P A levels are generally not g e n d e r specific, with both b o y s a n d girls demonstrating the s a m e trends. A few studies h a v e detected g e n d e r differences in this relationship but it is not consistent between studies (22, 2 7 , 78). Girls typically carry more fat than b o y s a n d are a l s o typically l e s s active (27).  15  Table 2.2. Description of investigations examining the relationship of PA and weight status. PA=physical activity, HR=heart rate, BMI=body mass index Author (Year) Raitakari et al. (1997)  Subjects  Measurement Tools  Results  N = 2358  Height, weight,  Higher P A levels were  Boys = 1114, Girls =  subscapular skinfold, P A  associated with lower  1244  questionnaire.  BMI in males and  Age: 9-24 years  skinfolds in males and females.  Rowlands et al. (1999)  N = 34  Height, weight, skinfolds,  P A measures from the  B o y s = 17, Girls = 17  Tritrac RT3  Tritrac and pedometer  Ages: 8.3-10.8 years  accelerometer,  had significant inverse  pedometer (worn 6 days),  correlations with  HR telemetry (worn 1  fatness.  day). Ekelund et al. (2001)  Abbott & Davies (2004)  N = 82  Height, weight, skinfolds,  No significant  Boys = 42, Girls = 40  HR monitoring (3 days)  relationships between  Age: 14.8 years  converted to total energy  P A variables and body  expenditure.  fat.  N = 47  Height, weight, ' ° 0  P A was significantly  Boys = 23, Girls = 24  dilution space (body fat),  inversely correlated with  Age: 5-10.5 years  doubly -labelled water  percentage body fat and  (10 day urine collection),  BMI.  Tritrac R3D (worn for 4 days). Janssen et al. (2005)  N =137593  Self-report questionnaire  Significant inverse  No gender  to obtain height, weight,  relationship between P A  differenentiation  PA.  and BMI classification in  Age: 10-16 years Dencker et al. (2006)  29/34 countries.  N = 248  Height, weight, dual  Children with higher  B o y s = 126, Girls =  energy x-ray  percentage body fat  101  absorptiometry, Actigraph  were significantly less  Age: 8.6-11.0 years  accelerometer (worn 4  active. Only vigorous  days).  P A was linked to obesity status.  16  2.3.2 P h y s i c a l Activity a n d V a s c u l a r Status E p i d e m i o l o g i c a l studies h a v e demonstrated that physically inactive adults have higher blood p r e s s u r e ( B P ) than their physically active counterparts a n d h a v e a n i n c r e a s e d risk of d e v e l o p i n g hypertension (30). S i n c e hypertension is a primary risk factor for C V D , the d i a g n o s i s , treatment, a n d prevention of high B P is important (79). W a r e h a m et a l . (30) s u g g e s t s that low habitual e n e r g y e x p e n d i t u r e ( P A ) is closely related to i n c r e a s i n g B P a n d that it w o u l d only take a 30 minute w a l k m o s t d a y s of the w e e k to a c h i e v e a significant drop in systolic blood p r e s s u r e ( S B P ) v a l u e s in the adult population. O v e r a s e v e n - y e a r s p a n in the C a n a d i a n population the best predictor of B P at the e n d of the s e v e n y e a r s w a s the b a s e l i n e B P m e a s u r e (79). In f e m a l e s , P A levels w e r e a l s o a significant predictor of follow-up B P (79). Interventions a i m e d at increasing P A levels (and c o n s e q u e n t l y d e c r e a s i n g the p r e v a l e n c e of C V D risk in children) h a v e the potential to result in long-term health benefits. In the C a r d i o v a s c u l a r R i s k in Y o u n g F i n n s Study, there w e r e no differences in systolic or diastolic blood p r e s s u r e between active a n d inactive children (14) which would s u g g e s t that P A h a s little effect on v a s c u l a r health in children or that the detrimental effects of a n inactive lifestyle o n the v a s c u l a r s y s t e m a r e not a d v a n c e d e n o u g h to be d e t e c t e d by m e a s u r e s of B P in children. O t h e r investigations h a v e a l s o found that daily P A in youth w a s not related to either S B P or diastolic blood p r e s s u r e ( D B P ) (23, 24) or the a s s o c i a t i o n s found w e r e w e a k (80). S o m e s t u d i e s h a v e noted a lower B P in the m o r e active children. W h e n body fat w a s a c c o u n t e d for in t h e s e studies, the relationship d i s a p p e a r e d (12). S t u d i e s e x a m i n i n g c h a n g e s in B P , both S B P a n d D B P , m e a s u r e s o v e r time are e q u i v o c a l with s o m e detecting a s e c u l a r i n c r e a s e a n d others reporting a d e c r e a s e in children (81). A difference h a s b e e n detected b e t w e e n g e n d e r s with b o y s having a slightly higher S B P than girls of the s a m e a g e (82).  2.3.3 P h y s i c a l Activity a n d M u s c u l o s k e l e t a l F i t n e s s High levels of m u s c u l o s k e l e t a l fitness in adults are a s s o c i a t e d with positive health status (83) a n d a r e a l s o related to i n d e p e n d e n c e , a n d functional p e r f o r m a n c e in elderly individuals (3, 83). In J a p a n e s e m e n p o o r m u s c u l a r fitness w a s a s s o c i a t e d with a n i n c r e a s e d risk of mortality (84) a n d in work by K a t z m a r z y k a n d C r a i g (85), a n i n c r e a s e d risk of a l l - c a u s e mortality w a s found in m e n a n d w o m e n in the lower quartile for sit-up performance. H a n d g r i p , another indicator of m u s c u l o s k e l e t a l fitness, is a l s o a  17 significant predictor of mortality in adult m e n (86). A l t h o u g h current e v i d e n c e states that m u s c u l o s k e l e t a l fitness is protective against C V D risks a n d c o m p l i c a t i o n s , more r e s e a r c h is required to clarify the distinct relationships b e t w e e n the various m e a s u r e s of m u s c u l o s k e l e t a l fitness a n d the health-related benefits they provide. R e c e n t data s u g g e s t s that increasing m u s c u l o s k e l e t a l fitness m a y help to prevent unhealthy weight gain in the C a n a d i a n population (87). T h e relationship b e t w e e n m u s c u l o s k e l e t a l fitness a n d P A is inconsistent in children a n d h a s not b e e n r e s e a r c h e d extensively. A few studies h a v e d e m o n s t r a t e d a significant but w e a k - t o - m o d e r a t e relationship b e t w e e n P A a n d v a r i o u s m e a s u r e s of m u s c u l o s k e l e t a l fitness (25, 26). Longitudinal studies of a d o l e s c e n t s d e m o n s t r a t e a positive influence of habitual P A o n upper body m u s c u l a r e n d u r a n c e (88). In children, g r a d e s 4 to 6, it w a s found that tracking for sit-and-reach a n d pull-ups w a s high, a n d for sit-ups w a s moderate over a three y e a r time period (89). In the C a n a d i a n population, there is moderate-to-high stability of sit-ups, grip strength, a n d sita n d - r e a c h o v e r a s e v e n - y e a r time frame (84). T h i s study s u g g e s t e d that m u s c u l o s k e l e t a l fitness tracks better than P A levels a n d that the stability i n c r e a s e s in adulthood. T h e r e are h o w e v e r , consistent d e c r e a s e s throughout the y e a r s in all m e a s u r e s of m u s c u l o s k e l e t a l fitness indicators beginning at approximately the m i d t e e n s to early 2 0 ' s (84).  2.3.4 P h y s i c a l Activity a n d Cardiorespiratory F i t n e s s E v i d e n c e supporting the importance of childhood p h y s i c a l fitness a n d P A a s protective a g a i n s t health-related complications is b e c o m i n g increasingly prevalent (60). Cardiorespiratory fitness a n d P A are thought to be important determinants of C V D risk in youth (14). S i n c e both cardiorespiratory fitness a n d P A track at moderate levels a c r o s s the lifespan (7) early m e a s u r e m e n t a n d prevention is imperative to i n c r e a s e P A a n d fitness in later y e a r s (60).  It is already e s t a b l i s h e d that low cardiorespiratory  fitness in adults is a strong predictor of C V D a n d a l l - c a u s e mortality (3).  Fortunately,  e v e n w h e n C V D risk factors are present in m e n , high levels of cardiorespiratory fitness offer s o m e d e g r e e of protection against premature mortality (7). In c r o s s - s e c t i o n a l a n d longitudinal studies a n d in s t u d i e s of large s a m p l e s i z e (n £ 186) it h a s b e e n d e m o n s t r a t e d consistently that m o r e active youth perform better in c a r d i o v a s c u l a r e n d u r a n c e t a s k s (7, 2 7 , 90). R e c e n t s t u d i e s of varying s a m p l e s i z e s  18  h a v e b e e n m o r e c o n s i s t e n t in detecting a significant relationship b e t w e e n a e r o b i c fitness a n d P A in children w h e n objective m e a s u r e m e n t tools w e r e utilized. This relationship b e c o m e s stronger w h e n aerobic fitness is related to time spent in vigorous P A a s o p p o s e d to all time s p e n t in P A (29, 91), but this a l s o is not consistent a c r o s s studies (28). T h e relationship b e t w e e n a e r o b i c fitness a n d P A l e v e l s w a s found to b e similar b e t w e e n g e n d e r s (27, 2 9 , 6 0 , 92) despite b o y s attaining higher aerobic fitness s c o r e s a n d P A levels than girls ( s e e T a b l e 2.3).  2.3.5 S u m m a r y In children, there is i n c r e a s i n g e v i d e n c e of a positive relationship b e t w e e n weight status a n d P A (21, 22), a n d cardiorespiratory fitness a n d P A (26, 29). T o date, there is no e v i d e n c e of a relationship b e t w e e n v a s c u l a r health a n d P A (12) a n d the relationship b e t w e e n m u s c u l o s k e l e t a l fitness a n d P A is w e a k to m o d e r a t e at best (25, 26). T h e s e trends are generally similar in both g e n d e r s . M e a s u r e m e n t of both P A a n d fitness c o m p o n e n t s a r e difficult in children a n d m a y partially e x p l a i n w h y stronger relationships h a v e not b e e n d e t e c t e d . A s s u c h , the third objective of this investigation is to determine the relationship b e t w e e n P A a n d health-related p h y s i c a l fitness using a n objective P A m e a s u r e m e n t tool. W e h y p o t h e s i z e that children that participate in more M V P A per d a y will h a v e higher health-related p h y s i c a l fitness s c o r e s .  19 T a b l e 2.3. Description of investigations e x a m i n i n g the relationship b e t w e e n P A a n d cardiorespiratory fitness. E E = e n e r g y expenditure, T E E = t o t a l daily e n e r g y expenditure « n u  =  a  C  ^ £  e  J  l  e  r  g  y  e  x  P  e  n  d  i  t  u  1 5 0 b p m , HR=heart rate. Author (Year) Dencker et al. (2006)  r  e  - P W C 1 5 0 = p h y s i c a l w o r k i n g c a p a c i t y at a heart rate of  Subjects  Measurement Tools  N = 477  BMI, self-evaluated  A weak but significant  B o y s = 140, Girls = 108  Tanner Stage, MTI model  relationship between  Age: 8-11 years  7164 accelerometer  V0 eakand mean daily  (worn 4 days), indirect  PA. The correlation  measurement V0 peak on  between V 0  cycle ergometer.  vigorous P A was stronger.  N = 34  Height, weight, skinfolds,  Output measures from  Boys = 17, Girls = 17  Trirac Rt3 accelerometer,  Tritrac and pedometer  Age: 8.3-10.8 years  pedometer (worn 6 days),  were significantly and  HR telemetry (worn 1  positively correlated with  day), endurance time on  aerobic fitness. HR had a  Bruce Maximal Protocol  weaker correlation to  Test.  fitness.  Height, weight, skinfolds,  V0 eak was significantly  Boys = 42, Girls = 40  HR monitoring (3 days)  and positively related to  Age: 14.8 years  converted to T E E , indirect  AEE.  2  Rowlands et al. (1999)  Ekelund et al. (2001)  Results  N = 82  2p  2 p e a k  and  2p  measures of V0 eak on 2p  treatmill, maturity. Pate et al. (1990)  N = 1558  2 questionnaires, 1  P A and physical fitness  Boys = 776, Girls = 782  completed by teacher and  were significantly and  Grades: 3-4  1 by parent (PA),  positively associated.  skinfolds, 1.6km run/walk time test.  2.4 Motor P e r f o r m a n c e in C h i l d h o o d T h r o u g h o u t middle c h i l d h o o d a n d a d o l e s c e n c e , differences exist b e t w e e n g e n d e r s a n d a g e g r o u p s in motor p e r f o r m a n c e (93), which affects the ability of the children to participate in P A a n d perform the health-related fitness t a s k s . T h u s , the relationship b e t w e e n habitual P A a n d fitness m a y be c o n f o u n d e d by c h a n g e s a s s o c i a t e d with normal growth a n d maturation (25). C r o s s - s e c t i o n a l d a t a h a s indicated that m o r e active b o y s h a v e better l e v e l s of motor p e r f o r m a n c e (94). P e r f o r m a n c e steadily improves in  20  b o y s until 17 or 18 y e a r s of a g e a n d in girls, p e r f o r m a n c e p l a t e a u s at 14 y e a r s of a g e (95). Until a g e 14, girls' p e r f o r m a n c e is on a v e r a g e within o n e s t a n d a r d deviation of b o y s ' performance. E x c e s s body fat negatively affects motor p e r f o r m a n c e , especially w h e n m o v e m e n t of the entire body is required. H o w e v e r , the bigger child is typically the stronger child (93). T h i s s e c t i o n e x a m i n e s the d e v e l o p m e n t of the c o m p o n e n t s of health-related p h y s i c a l fitness throughout childhood a n d a d o l e s c e n c e .  2.4.1 M u s c u l a r Strength a n d E n d u r a n c e Strength i n c r e a s e s linearly with chronological a g e a n d follows a growth pattern that is similar to the growth spurt pattern that o c c u r s in a d o l e s c e n c e (96, 97). T h e r e are s e x differences in the d e v e l o p m e n t of strength (95, 97), with b o y s demonstrating greater strength than girls (93) a n d having greater g a i n s in performance (98). F o r e x a m p l e , grip strength in m a l e s i n c r e a s e s by o v e r 3 0 0 % from a g e s 7 to 17 y e a r s (99) w h e r e a s grip strength in f e m a l e s i n c r e a s e s by approximately 2 6 0 % (100). T h i s difference in strength is not substantial until after approximately 13 y e a r s of a g e (97). S e x differences m a y be d u e in part to the greater s i z e a n d fat-free m a s s a d v a n t a g e of b o y s . In addition, b o y s tend to d e m o n s t r a t e greater strength per unit of m u s c l e a r e a t h a n girls (93). I n c r e a s e s in m u s c u l a r e n d u r a n c e are similar to t h o s e in strength a n d o c c u r until around a g e 17 in b o y s a n d a g e 13-15 in girls a s m e a s u r e d by the flexed a r m hang (98) a n d sit-up test (101). P e r f o r m a n c e in b o y s e x c e e d e d that of girls in both tests (98).  In  the flexed a r m h a n g b o y s improved by 1 4 3 % from a g e s 5 to 10 w h e r e a s girls improved only 9 7 % during the s a m e time s p a n (98).  2.4.2 Cardiorespiratory F i t n e s s M a x i m a l o x y g e n c o n s u m p t i o n , a m e a s u r e of a e r o b i c e n d u r a n c e , improves until the late t e e n s (102), h o w e v e r w h e n reported relative to body weight v a l u e s remain stable in b o y s from 8 to 18 y e a r s at a r o u n d 4 8 - 5 0 ml-kg" min" but d e c l i n e in girls from 4 5 - 3 5 1  1  ml-kg" -min" (102). B e t w e e n the a g e s of 10 - 12 y e a r s , b o y s ' v a l u e s a r e approximately 1  1  1 2 % higher than girls. M o r e specific to performance tests of a e r o b i c e n d u r a n c e , running s p e e d i n c r e a s e s linearly from 5 y e a r s until 17 y e a r s in b o y s a n d 11 or 12 y e a r s in girls with only a slight c h a n g e thereafter (93). After 9 y e a r s of a g e m a l e s h a v e better running s c o r e s than f e m a l e s . In tests of m a x i m a l o x y g e n c o n s u m p t i o n a n d running  21 s p e e d , the p e r f o r m a n c e difference b e t w e e n m a l e s a n d f e m a l e s b e c o m e s magnified during a d o l e s c e n c e (93).  2.4.3 Flexibility In m a l e s , flexibility a s m e a s u r e d by the sit-and-reach test, d e c l i n e s after a g e 8 until approximately a g e 12 after w h i c h it i n c r e a s e s until a g e 18. In f e m a l e s , flexibility i n c r e a s e s to a g e 14 y e a r s (93). T h e differential i n c r e a s e in flexibility in b o y s a n d girls at a g e s 13 a n d 11 respectively, parallels their respective growth spurts in trunk length (98). Overall, m a l e s e x p e r i e n c e a net l o s s in flexibility w h e r e a s f e m a l e s e x p e r i e n c e a slight i n c r e a s e to a g e 14 or 15 (98). F e m a l e s are m o r e flexible t h a n m a l e s at all a g e s (93, 98).  2.4.4 S u m m a r y Motor p e r f o r m a n c e m a y affect the ability of children to perform P A a n d c o m p o n e n t s of the health-related p h y s i c a l fitness tests, thereby c o n f o u n d i n g the relationship b e t w e e n P A a n d fitness. B o y s outperform girls on most t a s k s , e x c l u d i n g flexibility, a n d this difference b e c o m e s magnified throughout a d o l e s c e n c e . P e r f o r m a n c e in girls typically p l a t e a u s a r o u n d a g e s 12 to 14 w h e r e a s b o y s continue to improve until a g e 17 or 18.  M o r e r e s e a r c h is n e e d e d to provide a clear a n d definitive relationship between P A levels in children a n d m e a s u r e s of health-related p h y s i c a l fitness. A s w e l l , r e s e a r c h specifically a i m e d at e x a m i n i n g the difference in P A patterns a n d health-related fitness v a r i a b l e s within ethnic g r o u p s are in n e e d b e c a u s e there is the potential for genetic susceptibility to c a r d i o v a s c u l a r risk factors in s o m e populations. Motor performance affects the ability of children to participate in a n d perform v a r i o u s p h y s i c a l t a s k s a n d therefore is a n important consideration w h e n e x a m i n i n g t h e s e relationships in children.  2.5 A s s e s s i n g P h y s i c a l Activity Objective m e a s u r e s of P A n e e d to be obtained from children in order to correctly a s s e s s their current level of P A a n d its relationship to m e a s u r e s of health-related physical fitness. A s s e s s i n g P A in children is more c h a l l e n g i n g than in adults d u e to the unique d e v e l o p m e n t a l a n d behavioural a s p e c t s of children. A study by B a i l e y et al. (31) found that while o b s e r v i n g children 9 5 % of the vigorous activities lasted l e s s than 1 5 s  22  a n d 9 5 % of the rest p e r i o d s w e r e l e s s than 1 5 s . F r o m this d a t a the author d e d u c e d that short, intermittent bouts of v i g o r o u s activity with frequent rest periods of longer duration are typical of children. Similarly, B a q u e t et a l . (39) d e t e r m i n e d that 8 0 % of the M P A bouts a n d o v e r 9 3 % of the V P A bouts in children lasted l e s s t h a n 10s. A l t h o u g h there are m a n y instruments a v a i l a b l e for P A m e a s u r e m e n t , few are a b l e to capture children's activity accurately. T h e following section d e s c r i b e s m e t h o d s available for monitoring P A a n d reviews the strengths a n d limitations of e a c h .  2.5.1 S e l f - R e p o r t Q u e s t i o n n a i r e s a n d s u r v e y s h a v e traditionally b e e n u s e d to m e a s u r e P A levels a n d although t h e s e m e t h o d s a p p e a r to be a c c e p t a b l e to u s e in adult studies, their a c c u r a c y with respect to children is highly q u e s t i o n a b l e (103). It h a s b e e n d o c u m e n t e d that children l e s s t h a n 12 y e a r s of a g e are not a b l e to recall activities accurately or quantify the time-frame of activity (104). T h i s is b e c a u s e children h a v e l e s s d e v e l o p e d cognitive skills a n d therefore are l e s s able to effectively u s e self-report questionnaires. V i g o r o u s P A is generally o v e r e s t i m a t e d using self-report m e t h o d s d u e to a child's e x a g g e r a t e d perception of time a n d / o r effort a n d the difficulty in correctly capturing s p o r a d i c bouts of activity (32, 105). H o w e v e r , P A of moderate intensity c a n b e a c h i e v e d through m a n y daily activities w h i c h are not typically thought to contribute to P A , a r e n o n - p l a n n e d , l e s s m e m o r a b l e a n d quantifiable, a n d therefore more likely to b e underestimated by selfreport m e t h o d s utilized with children (15, 38).  2.5.2 Direct O b s e r v a t i o n Direct o b s e r v a t i o n of P A h a s distinct a d v a n t a g e s o v e r other m e t h o d s of a s s e s s i n g P A with the m o s t significant o n e b e i n g the high resolution at w h i c h P A is recorded. Trained o b s e r v e r s h a v e the ability to m e a s u r e the duration, intensity, a n d frequency of specific activities in a variety of e n v i r o n m e n t s a n d are a l s o a b l e to capture s p o r a d i c or short bouts of activity (31). T h i s method allows for c o m p r e h e n s i v e information to be gathered about the subject's P A patterns. T h e limitations of this t e c h n i q u e are that it requires a substantial a m o u n t of time for a d e q u a t e staff training a n d d a t a collection (31) a n d is therefore costly (46). In addition, subject reactivity m a y b e problematic d u e to the p r e s e n c e of a trained o b s e r v e r (46). T h e observation t e c h n i q u e is not f e a s i b l e in large investigations d u e to t i m e constrictions. A l s o , studies utilizing direct observation a s the  23  method of a s s e s s i n g P A a r e l e s s than 12 hours in duration (21). T h i s eliminates the possibility of looking at habitual P A patterns a n d t e m p o r a l or s e a s o n a l variations.  2.5.3 Heart R a t e Monitoring Heart rate ( H R ) monitoring h a s b e e n a c c e p t e d a s a valid a n d reliable m e a s u r e of P A but it is a n indirect m e a s u r e that indicates the relative s t r e s s p l a c e d o n the c a r d i o v a s c u l a r s y s t e m (106). It is b a s e d on the a s s u m p t i o n of a linear relationship b e t w e e n H R a n d o x y g e n c o n s u m p t i o n . Heart rate d a t a is strongly related to energy expenditure, c a n be utilized in large studies a n d c a n collect d a t a in small time intervals over a relatively long time period (32, 51). T h i s linear relationship b e t w e e n H R a n d o x y g e n c o n s u m p t i o n allows intensity of activity to be d e t e r m i n e d . Unfortunately this relationship is no longer linear at high intensities of activity a n d is therefore l e s s a c c u r a t e during v i g o r o u s activity. A n o t h e r downfall of this m e t h o d is that H R is sensitive to emotional s t r e s s , environmental stress, a n d body position. A s well, s i n c e H R r e s p o n s e t e n d s to lag b e h i n d c h a n g e s in p h y s i c a l m o v e m e n t , the rapid transitions b e t w e e n intensity of m o v e m e n t in children m a y be m a s k e d (51, 105).  2.5.4 P e d o m e t e r s P e d o m e t e r s provide a n objective m e a s u r e of total step counts o v e r a g i v e n period but m o s t d o not h a v e the ability to look at f r e q u e n c y or intensity of P A , time stamp the step counts (32) or store d a t a for e x t e n d e d periods (107). N e w e r m o d e l s are times t a m p e d , thus o v e r c o m i n g s o m e of the previous limitations. T h e y a r e not a b l e to record counts during cycling or i n c r e a s e s in e n e r g y expenditure d u e to i n c r e a s e d load or m o v e m e n t up a n incline (46). T h e y are a l s o k n o w n to underestimate v i g o r o u s intensity P A (53) a n d a r e relatively e a s y to tamper with. T h e y are h o w e v e r , i n e x p e n s i v e , reusable a n d non-reactive tools suitable for u s e in l a r g e - s c a l e investigations (108).  2.5.5 Indirect Calorimetry U n d e r controlled laboratory conditions indirect calorimetry is u s e d to determine e n e r g y expenditure a s s o c i a t e d with resting metabolic rate, the thermic effect of food, a n d the thermic effect of e x e r c i s e (32). M o r e recently, portable, lightweight metabolic s y s t e m s h a v e b e e n introduced. T h e y c a n be u s e d under free-living conditions but this is still too c u m b e r s o m e to be undertaken with children (46) a n d is not a f e a s i b l e option in a  24  large s c a l e study. A major limitation of this technique is its inability to e x a m i n e the specifics of P A patterns (32).  2.5.6 D o u b l y - L a b e l e d W a t e r D o u b l y - l a b e l e d water is c o n s i d e r e d to be the gold standard m e a s u r e m e n t of energy expenditure or P A in free-living situations (46). D o u b l y - l a b e l e d w a t e r g i v e s a direct m e a s u r e of c a r b o n dioxide production a n d d i s a p p e a r a n c e rates of the isotopes in the urine, blood, or s a l i v a (4). T h i s yields estimates of e n e r g y expenditure, taking the thermic effect of food into consideration. It is b a s e d on the difference in rates of turnover of h y d r o g e n a n d o x y g e n in body water (4). It is n o n - i n v a s i v e a n d c a n m e a s u r e activity o v e r a period of 1 - 2 w e e k s (32) a n d h a s low reactivity (46) but is a l s o e x p e n s i v e (32). A n important consideration is that e n e r g y expenditure is a physiological c o n s e q u e n c e of P A a n d the two are distinct constructs s o it cannot directly m e a s u r e P A (46). U s i n g this method it is i m p o s s i b l e to determine specific P A patterns (32, 46).  2.5.7 A c c e l e r o m e t r y T o accurately a s s e s s children's activity patterns, the instrument must be sensitive e n o u g h to detect, c o d e , or record s p o r a d i c a n d intermittent activity (32, 109). T h e a c c e l e r o m e t e r is a unique a n d useful p i e c e of technology that is a b l e to capture a n d store activity patterns in s m a l l time intervals over a n e x t e n d e d period of time. T h i s d e v i c e is a l s o s m a l l a n d unobtrusive, (110) permitting participant f r e e d o m of movement. T h e a c c e l e r o m e t e r is a b l e to m e a s u r e the intensity of body or b o d y s e g m e n t accelerations through s o m e form of piezoelectric or p i e z o r e s i s t i v e acceleration s e n s o r technology (1). T h e s e n s o r c o n s i s t s of a piezoelectric e l e m e n t a n d a s e i s m i c m a s s . W h e n the s e n s o r u n d e r g o e s acceleration the s e i s m i c m a s s c a u s e s the piezoelectric element to b e n d a n d a voltage signal that is proportional to the applied acceleration is emitted (4). R e c o r d e d a c c e l e r a t i o n s are converted to a quantifiable digital signal referred to a s a 'count' (46). Frequency-filtering t e c h n i q u e s a r e incorporated into the units to e x c l u d e a c c e l e r a t i o n s unlikely to b e g e n e r a t e d by h u m a n m o v e m e n t (1). T h e a c c e l e r o m e t e r is a b l e to m e a s u r e important health-related d i m e n s i o n s of P A s u c h a s frequency, duration, a n d intensity of m o v e m e n t , a n d provide a chronological recording of t h e s e c o m p o n e n t s (103). A downfall of this d e v i c e is that not all activity is reflected in a c c e l e r a t i o n a n d deceleration s u c h a s upper b o d y m o v e m e n t s , m o v e m e n t  25 up an incline, a n d cycling (32, 110). Despite t h e s e limitations the a c c e l e r o m e t e r h a s b e e n found to be a valid tool to u s e w h e n m e a s u r i n g P A in children (103, 111) b e c a u s e the most c o m m o n activities participated in by children are locomotor in nature (such a s s o c c e r , brisk w a l k i n g , a n d g e n e r a l play or c h a s i n g g a m e s ) (40).  2.5.8 S u m m a r y N u m e r o u s tools a r e a v a i l a b l e to a s s e s s P A , e a c h a s s o c i a t e d with specific limitations a n d strengths. T h e a c c e l e r o m e t e r a p p e a r s to b e a n i d e a l m e a s u r e m e n t tool to u s e for a s s e s s m e n t of children in field s t u d i e s d u e to its ability to capture s p o r a d i c activity in short time intervals o v e r e x t e n d e d time periods. A robust a n d a c c u r a t e P A m e a s u r e m e n t tool, s u c h a s the a c c e l e r o m e t e r , is required to obtain a thorough understanding of the unique P A patterns o b s e r v e d between ethnic groups a n d to e x a m i n e the relationship b e t w e e n P A a n d v a r i o u s c o m p o n e n t s of healthrelated p h y s i c a l fitness in children.  C H A P T E R III  Methodology 3.1 Participants Participants w e r e a s u b - s a m p l e of the 1459 involved in the A S ! B C initiative a n d included a multi-cultural group of 579 b o y s (n = 284) a n d girls (n = 295) in g r a d e s four to five (ages 8 to 11) from s c h o o l s (n = 9) in the G r e a t e r V a n c o u v e r R e g i o n . O f t h e s e children, 36 students w e r e a b s e n t o n the d a y the activity monitors w e r e distributed, 11 technical errors o c c u r r e d with the d e v i c e s , s e v e n children m o v e d b e t w e e n the time of c o n s e n t a n d d a t a collection, a n d o n e child refused to w e a r the d e v i c e . F r o m this group, 106 of the children w o r e the monitor during a w e e k in w h i c h a P r o f e s s i o n a l D e v e l o p m e n t D a y o c c u r r e d . Initial examination of the d a t a s u g g e s t e d that the P r o f e s s i o n a l D e v e l o p m e n t D a y altered the P A profile a n d therefore t h e s e children w e r e r e m o v e d from the a n a l y s i s . O n e s c h o o l (n = 44) w o r e the monitors o v e r a different time period (Friday to T u e s d a y ) d u e to technical difficulties. A s a result the children had only o n e full w e e k d a y of w e a r a n d thus, w e r e a l s o r e m o v e d from the a n a l y s i s . Children (n = 12) with less than 3.5 d a y s w o r e the monitor for a n a v e r a g e of two hours less per d a y a n d w e r e a l s o r e m o v e d . In the remaining group of children, only those that wore the monitor during the a v e r a g e ' o n ' a n d 'off' times w e r e retained for a n a l y s i s . O n e of t h e s e children w a s r e m o v e d d u e to physiologically unlikely B P d a t a (143/128), two participants h a d B P r e a d i n g s that e x c e e d e d 1 2 0 / 8 0 , three children h a d no d a t a for the health-related p h y s i c a l fitness m e a s u r e s , a n d 17 children w e r e of ethnic g r o u p s other than C a u c a s i a n or A s i a n . O n e - h u n d r e d s e v e n t y participants (n = 7 9 b o y s a n d n = 91 girls) from five s c h o o l s w e r e retained for the final a n a l y s i s . Written informed c o n s e n t w a s obtained from the parents and/or local g u a r d i a n s of the children. T h e investigation w a s carried out a c c o r d i n g to the ethical guidelines set by the University Clinical R e s e a r c h E t h i c s B o a r d for r e s e a r c h involving h u m a n participants (see A p p e n d i x A for ethics forms).  3.1.1 G e n e r a l Participant C h a r a c t e r i s t i c s Birth-date, g e n d e r a n d ethnicity w e r e provided by the parents a n d / o r g u a r d i a n s on the Health History Q u e s t i o n n a i r e ( s e e A p p e n d i x B). C h i l d r e n ' s ethnicity w a s determined, for e x a m p l e , a s b e i n g North A m e r i c a n a n d / o r E u r o p e a n if both parents or  27  all four grandparents w e r e born in North A m e r i c a or E u r o p e . If the ethnicity data provided on the q u e s t i o n n a i r e w a s not clear or w a s incomplete the child w a s a s k e d to classify their parents a n d g r a n d p a r e n t s birthplace to d e t e r m i n e ethnicity. If the information w a s still incomplete, a n y child that h a d , for e x a m p l e , both parents or all four grandparents born in C a n a d a (and/or E u r o p e ) the child w a s c o n s i d e r e d 'North A m e r i c a n / E u r o p e a n ' . F o r the p u r p o s e s of this investigation, children w e r e classified a s : 1) C a u c a s i a n ( E u r o p e a n decent), 2) A s i a n (South, E a s t a n d S o u t h e a s t ) or 3) other. O n l y children in the first two classifications w e r e u s e d in the a n a l y s i s b e c a u s e the s a m p l e l a c k e d sufficient participants from other ethnic g r o u p s .  3.2 C a r d i o v a s c u l a r D i s e a s e R i s k A s s e s s m e n t s  3.2.1 Anthropometry Height (cm) w a s m e a s u r e d to the nearest 1 m m with a portable stadiometer. W e i g h t (kg) w a s r e c o r d e d to the nearest 0.1 kg on an electronic s c a l e ( S E C A G e r m a n y ) . S h o e s w e r e r e m o v e d for both of t h e s e m e a s u r e s . T w o m e a s u r e m e n t s of height a n d weight w e r e a v e r a g e d for a n a l y s i s .  BMI (kg/m ) w a s c a l c u l a t e d from t h e s e m e a s u r e s . 2  C l a s s i f i c a t i o n s of our participant's weight to height status w a s defined by internationally e s t a b l i s h e d v a l u e s (112). W a i s t circumference w a s t a k e n m i d w a y b e t w e e n the iliac crest a n d the bottom of the ribcage with a n anthropometric t a p e (113). This m e a s u r e w a s taken o v e r top of a light shirt. T w o m e a s u r e m e n t s w e r e taken a n d a v e r a g e d for analysis.  3.2.2 V a s c u l a r H e a l t h Participants h a d their B P taken using a n automatic s p h y g m o m a n o m e t e r (left arm). Resting heart rate w a s obtained simultaneously. S y s t o l i c a n d diastolic B P (mmHg) a n d resting H R (bpm) m e a s u r e m e n t s w e r e u s e d in t h e s e a n a l y s e s . C h i l d r e n with resting B P a b o v e the 9 5  t h  percentile (120/80) w e r e e x c l u d e d from further testing.  3.2.3 M u s c u l o s k e l e t a l F i t n e s s T h e m u s c u l o s k e l e t a l fitness c o m p o n e n t of this investigation w a s c o m p r i s e d of grip strength, p u s h - u p s , curl-ups a n d sit-and-reach. T h e a s s e s s m e n t protocols are modified v e r s i o n s of t h o s e d e v e l o p e d by C S E P (114). F o r a detailed description of testing  28  instructions refer to A p p e n d i x C . C h i l d r e n w e r e a s k e d to c o m p l e t e a s m a n y p u s h - u p s a n d curl-ups a s p o s s i b l e . M a x i m u m grip strength w a s d e t e r m i n e d by s u m m i n g the m a x i m u m s c o r e from the greater of two trials of the right a n d left h a n d . Sit-and-reach s c o r e s w e r e d e t e r m i n e d by the m a x i m u m distance r e a c h e d o v e r two trials. M a x i m u m grip strength (kg) a n d s i t - a n d - r e a c h (cm) s c o r e s w e r e u s e d in t h e s e a n a l y s e s .  3.2.4 C a r d i o v a s c u l a r F i t n e s s C a r d i o v a s c u l a r fitness w a s m e a s u r e d via the shuttle run w h i c h has b e e n found to be reliable in children (115). F o r the L e g e r shuttle run, the children w e r e required to run back a n d forth b e t w e e n a 2 0 m d i s t a n c e a n d t o u c h the 2 0 m line simultaneously with a s o u n d s i g n a l that emitted from a p r e r e c o r d e d tape. T h e starting s p e e d is 8.5 km/hr a n d is i n c r e a s e d by 0.5 km/hr e v e r y minute. T h e test w a s c o m p l e t e d w h e n the child w a s not a b l e to maintain the s e t p a c e . T h e total number of l a p s performed by e a c h child w a s recorded a n d further u s e d in the a n a l y s i s . T h e shuttle run permitted a s m a n y a s 15 - 2 0 children to run simultaneously.  3.2.5 P h y s i c a l Activity P h y s i c a l activity w a s m e a s u r e d objectively for 5 d a y s using the G T 1 M Activity Monitor. It is d e s i g n e d to ascertain normal h u m a n m o v e m e n t without impeding activity (103) a n d h a s b e e n s h o w n to provide valid and reliable e s t i m a t e s of childhood P A (71). T h e G T 1 M is s m a l l a n d c o m p a c t weighing 2 7 g a n d h a s d i m e n s i o n s of 3.8 x 3.7 x 1.8 c m . It is e q u i p p e d with 1 M e g a b y t e of non-volatile flash m e m o r y a n d a r e c h a r g e a b l e 3.7 V Lithium Ion battery. It is d e s i g n e d to detect acceleration s i g n a l s ranging in magnitude from 0.05 to 2.00 g with a frequency r e s p o n s e of 0.25 - 2.50 H z . This frequency is a b l e to detect normal h u m a n motion a n d reject motion from other s o u r c e s s u c h a s riding in a vehicle. E a c h s a m p l e is s u m m e d o v e r a u s e r - s p e c i f i e d e p o c h (116). F o r this investigation the e p o c h w a s s e t at 15 s e c o n d s a n d provided both acceleration a n d step-counts. A short e p o c h w a s c h o s e n in order to capture the short bouts of higher intensity activity performed by children. T h e activity monitor w a s attached to a n elastic belt a n d w o r n at the waist a b o v e the iliac crest. Participants w e r e a s k e d to w e a r the monitors for 5 c o n s e c u t i v e d a y s (3 w e e k d a y s a n d 2 w e e k e n d days) for 12 c o n s e c u t i v e hours e a c h d a y (8 a m - 8 pm w a s the s u g g e s t e d time interval) a s this is within the four to s e v e n d a y r e c o m m e n d e d time frame  for obtaining a reliable estimate of habitual P A (r = 0.80) (117).  T h e children w e r e  instructed to r e m o v e the monitors at night a n d while s w i m m i n g , bathing, or showering. T h e G T 1 M Activity Monitor m e a s u r e d the duration, f r e q u e n c y , a n d intensity of P A which w a s a s s e s s e d throughout the w e e k d a y a n d w e e k e n d d a y s . Specifically for this project, the o u t c o m e v a r i a b l e s u s e d w e r e : 1) a v e r a g e c o u n t s p e r day, 2) a v e r a g e counts per minute, 3) a v e r a g e M V P A a c c u m u l a t e d per day, 4) a v e r a g e M V P A a c c u m u l a t e d per w e e k d a y , 5) a v e r a g e M V P A a c c u m u l a t e d per w e e k e n d d a y , 6) a v e r a g e sporadic M V P A a c c u m u l a t e d p e r d a y , 7) a v e r a g e minutes of M V P A a c c u m u l a t e d in bouts of 5 minutes or more, a n d 8) M V P A a c c u m u l a t e d throughout the s c h o o l day. A g e - s p e c i f i c cut points w e r e obtained from Trost et a l . , (118) w h o performed a rigorous calibration study o n children of similar a g e with indirect calorimetry a s the criterion m e a s u r e . S i n c e these cut points w e r e e s t a b l i s h e d using 1 minute e p o c h s , the v a l u e s w e r e divided by 4 for u s e with the shorter e p o c h length utilized in this investigation (see T a b l e 3.1 for cut-points and classification of P A ) .  T a b l e 3.1. A g e - s p e c i f i c classification of physical activity intensity by M E T s a n d counts (per 15 s e c o n d s ) . Cut-points obtained from Trost et a l . (118). Intensity  METs  Counts (8yrs)  Counts (9 yrs)  Counts (10 yrs)  Counts (11 yrs)  <1.5  0-49  0-56  0-62  0-70  1.5-2.99  50-200  57-226  63-254  71-283  3-5.99  201-827  227-874  255-293  284-976  MVPA  3+  201-32767  227-32767  255-32767  284-32767  Vigorous  £6  828-32767  875-32767  924-32767  977-32767  Sedentary Light Moderate  3.3 P r o c e d u r e Participants w e r e e v a l u a t e d o v e r a o n e w e e k period. A trained r e s e a r c h t e a m of approximately three to four A S ! B C investigators c o n d u c t e d anthropometry, v a s c u l a r health, m u s c u l o s k e l e t a l fitness a n d c a r d i o v a s c u l a r fitness m e a s u r e s . F o r e a c h d a y of m e a s u r e m e n t s , children w e r e temporarily e x c u s e d from their c l a s s r o o m s in groups of 10 to 15 at a time. T e s t i n g took place in the g y m n a s i u m of the s c h o o l .  Day 1 consisted  of m e a s u r e m e n t s of anthropometry, v a s c u l a r health, m u s c u l o s k e l e t a l fitness, a n d c a r d i o v a s c u l a r fitness ( s e e Figure 3.1). D a y 2 involved the distribution of G T 1 M Activity  30  Monitors to all of the participating children in the s c h o o l . D a y 7 c o n s i s t e d of monitor pickup a n d gift distribution to the children w h o returned the monitors  Figure 3.1. S c h e m a t i c of testing procedure.  Day One Measurement of healthrelated fitness variables  Day Two Distribution of G T 1 M Activity Monitors  Day Three  GT1M  Activity Monitor pickup and gift distribution  3.3.1 D a y 1: W e i g h t S t a t u s , V a s c u l a r Health a n d H e a l t h - R e l a t e d P h y s i c a l F i t n e s s Measures T h e first d a y of a s s e s s m e n t s c o m p r i s e d of anthropometry, v a s c u l a r health, m u s c u l o s k e l e t a l fitness a n d cardiorespiratory fitness m e a s u r e m e n t s ( s e e Figure 3.2). M e a s u r e m e n t s of weight a n d W C a r e potentially sensitive i s s u e s with s o m e children. T o help alleviate a n y emotional anxiety children m a y e x p e r i e n c e during t h e s e m e a s u r e m e n t s , e a c h child h a d his or her weight status taken individually to e n s u r e privacy. V a s c u l a r health m e a s u r e m e n t s w e r e taken prior to p h y s i c a l testing. M u s c u l o s k e l e t a l testing (i.e., grip strength, p u s h - u p s , curl-ups a n d sit-and-reach) w a s c o n d u c t e d next, followed by the shuttle run. It is important that the shuttle run b e completed last b e c a u s e it requires m a x i m a l physical exertion a n d the fatigue the children e x p e r i e n c e after it is c o m p l e t e d m a y negatively affect the m u s c u l o s k e l e t a l tests. T h e s e tests took approximately o n e hour.  31  Figure 3.2 D a y 1: S c h e m a t i c outlining the testing p r o c e d u r e . Vascular Health  Resting Blood Pressure  Weight Status  Height  i  Musculoskeletal Fitness  Grip Strength  Cardiorespiratory Fitness Leger Shuttle Run  1  Weight  Sit-and-Reach  Waist Circumference  Push-ups  Partial Curl-up  3.3.2 D a y 2: Activity Monitor Distribution Day T w o a l w a y s o c c u r r e d o n a W e d n e s d a y . O n this d a y s c h o o l s w e r e entered in the morning a n d up to 7 5 students w e r e fitted with monitors. E a c h c l a s s r o o m of students that participated in t h e study w a s given a detailed talk instructing them a s to how a n d w h e n the monitors n e e d e d to b e worn. T h e n e a c h child w a s individually fitted with a monitor a n d given a n information p a c k a g e for their parent(s)/guardian(s). T h i s took approximately 3 0 minutes per c l a s s r o o m . P a r e n t s / g u a r d i a n s w e r e provided with a n information letter a n d contacted by p h o n e on the e v e n i n g that their child w a s fitted with a monitor to provide a n opportunity for clarifications to b e m a d e about the p u r p o s e a n d d e s i r e d o u t c o m e of the study a n d for general q u e s t i o n s ( s e e A p p e n d i x E for information letter). T h e parents w e r e a l s o a s k e d to complete a log w h i c h indicated the time the monitor w a s p l a c e d o n t h e child in the morning a n d t h e time it w a s r e m o v e d in the e v e n i n g , t h e times (if any) that the monitor w a s r e m o v e d during t h e day, a s well a s a n y u n u s u a l c i r c u m s t a n c e s in which the child's regular routine w a s significantly affected (i.e., illness, weather) ( s e e A p p e n d i x F for log).  32  3.3.3 D a y 7: Activity Monitor P i c k - U p Monitors w e r e returned to r e s e a r c h e r s the following M o n d a y morning at the s c h o o l . In e x c h a n g e for returning the monitor the students w e r e given a small gift a n d had their n a m e entered into a d r a w for a larger prize.  3.3.4 P h y s i c a l Activity D a t a R e d u c t i o n After e a c h w e e k of d a t a collection, the data w e r e immediately d o w n l o a d e d to a laboratory computer. D a t a w e r e then s c a n n e d for s p u r i o u s m e a s u r e s , malfunctioning units, a n d c o m p l i a n c e with w e a r guidelines. Monitor o n (time the child put the monitor on in the morning) a n d off (time the child r e m o v e d the monitor before bed) times w e r e determined using both the log s h e e t s a n d a visual inspection of the file. In the c a s e where the information on the log sheet did not match the d a t a in the file or the log sheet w a s not returned, the objective information in the file w a s u s e d . O n l y 1 3 % of the participants ( 5 4 . 5 % girls a n d 4 5 . 4 % boys) with u s a b l e P A d a t a did not return the log sheet. T h e participants w e r e required to w e a r the monitor for at least 3 d a y s of w e a r to be valid for a n a l y s i s ( s e e F i g u r e 3.1) a n d initially it w a s d e c i d e d that 8 hours would constitute a full d a y of w e a r (45). H o w e v e r , d u e to the large variability in the number of hours of w e a r (the range w a s 8 - 1 7 hrs) and hours of the d a y the monitor w a s worn, a day w a s c o n s i d e r e d valid if it fell within ± 2 standard deviations ( S D ) of the a v e r a g e 'on' a n d 'off time for that d a y . T h e a v e r a g e on a n d off times for e a c h d a y w e r e calculated to determine the n e w hours of a c c e p t a b l e w e a r ( s e e A p p e n d i x D for a v e r a g e w e a r hours per day). If a child w o r e the monitor too long (i.e., the monitor w a s put on before the a v e r a g e o n time or r e m o v e d after the a v e r a g e off time) the extra w e a r time w a s e x c l u d e d from the a n a l y s i s s o that all children w e r e w e a r i n g the monitor during the s a m e time f r a m e If files met the criteria for a n a l y s i s , the data w e r e subjected to c u s t o m software d e s i g n e d to optimize a n d s t a n d a r d i z e the production of P A o u t c o m e variables. T h i s software allows the u s e r to specify cut-points, time periods of interest to be e x a m i n e d , a n d fractionalizations of P A for further statistical a n a l y s e s .  33 Figure 3.3. D e c i s i o n tree for data reductiorj.  3.3.5 Statistical A n a l y s i s M e a n s a n d s t a n d a r d deviations ( S D s ) w e r e c a l c u l a t e d for all o u t c o m e variables. A l l variables w e r e tested for normal distribution (i.e., s k e w n e s s or kurtosis) a n d w e r e transformed w h e n n e c e s s a r y . Bivariate correlations w e r e u s e d to determine the relationships b e t w e e n all v a r i a b l e s . A n a l y s i s of V a r i a n c e ( A N O V A ) w a s c h o s e n to determine if there w e r e a n y differences in weight status, v a s c u l a r or health-related physical fitness b e t w e e n the children w h o h a d a c c e p t a b l e P A d a t a a n d t h o s e that did not. T-tests w e r e u s e d to determine if g e n d e r differences existed b e t w e e n variables. A n a l y s i s of C o v a r i a n c e ( A N C O V A ) w a s u s e d to investigate the a s s o c i a t i o n between ethnic g r o u p s ( C a u c a s i a n a n d A s i a n ) a n d a v e r a g e M V P A per d a y , counts per minute, a n d health-related p h y s i c a l fitness s c o r e s . T h e P A o u t c o m e v a r i a b l e s w e r e c h o s e n to c o m p a r e a n index of the a m o u n t a n d intensity of activity. P r e v i o u s literature h a s demonstrated that b o y s a n d girls are not a h o m o g e n o u s group (11, 2 7 , 3 8 , 52); therefore, A N C O V A s w e r e performed separately for b o y s a n d girls. T h e covariates w e r e c h o s e n b a s e d o n their k n o w n or o b s e r v e d relationship to P A in children. Factors that  m a y affect the relationship of P A to health-related p h y s i c a l fitness a n d c a r d i o v a s c u l a r health in children are: 1) weight (an i n c r e a s e in weight h a s b e e n related to d e c r e a s e d P A (22, 2 7 , 74)), 2) height (52), a n d 3) a g e (as a g e i n c r e a s e s P A d e c r e a s e s (37, 38, 52)). A m u s c u l o s k e l e t a l fitness c o m p o s i t e s c o r e w a s created u s i n g P r i n c i p a l C o m p o n e n t A n a l y s i s . V a r i a b l e s w e r e transformed into z - s c o r e s before b e i n g subjected to principal c o m p o n e n t a n a l y s i s to s t a n d a r d i z e units. T h e first principal c o m p o n e n t of the m u s c u l o s k e l e t a l fitness s c o r e s (sit-and-reach, curl-ups, p u s h - u p s , grip strength) w a s retained for further a n a l y s i s . T h e first principal c o m p o n e n t e x p l a i n e d 3 9 % of the v a r i a n c e in the original v a r i a b l e s . T h e correlations b e t w e e n the original variables a n d the first principal c o m p o n e n t a r e reported a s factor l o a d i n g s representing their p e r c e n t a g e contribution to the overall s c o r e . T h e factor l o a d i n g s w e r e 0.380 (sit-andreach), 0.762 (curl-ups), 0.678 (push-ups), a n d 0.612 (grip strength). P u s h - u p s , curlu p s a n d grip strength contributed significantly to the overall s c o r e with sit-and-reach contributing very little. F r o m the factor loadings, a total m u s c u l o s k e l e t a l fitness s c o r e is derived using the following formula (sit-and-reach * 0.380) + (curl-ups * 0.762) + ( p u s h u p s * 0.678) + (grip strength * 0.612). T h i s s c o r e is u s e d to c o m p a r e m u s c u l o s k e l e t a l fitness b e t w e e n the ethnic g r o u p s a n d to determine the relationship b e t w e e n P A a n d m u s c u l o s k e l e t a l fitness. Initially, a n a l y s e s w e r e carried out separately for b o y s a n d girls, h o w e v e r , s i n c e the factor loading w a s within 0.1 for all c o m p o n e n t s , the c o m p o n e n t s contributed similarly to the overall s c o r e a n d there w a s approximately only a 1% difference in e x p l a i n e d v a r i a n c e b e t w e e n b o y s a n d girls, the g r o u p s w e r e c o l l a p s e d into o n e to c r e a t e the c o m p o s i t e s c o r e . Hierarchical r e g r e s s i o n w a s u s e d to estimate the contribution of ethnicity a n d P A to health-related p h y s i c a l fitness c o m p o n e n t s . V a r i a b l e s w e r e e n t e r e d in the following order: 1) a g e , height, weight (control variables), 2) ethnicity (independent variable), 3) counts per minute (independent variable), 4) M V P A per d a y (independent variable). T h e order of variable input into the r e g r e s s i o n a n a l y s i s w a s d e t e r m i n e d through established relationships b e t w e e n a g e , weight, height (maturity) a n d the health-related physical fitness c o m p o n e n t s . Ethnicity w a s entered a s the s e c o n d step in the m o d e l a n d the P A o u t c o m e v a r i a b l e s w a s entered last to e x a m i n e the unique relationship b e t w e e n P A a n d fitness without the influence of the previous v a r i a b l e s .  Intraclass correlation ( I C C ) w a s calculated to e x a m i n e the m a g n i t u d e of variation b e t w e e n s c h o o l s . A 1-way A N O V A w a s run to obtain the s u m of s q u a r e s for b e t w e e n s c h o o l differences a n d within s c h o o l differences for total l a p s run in the L e g e r shuttle run, the m u s c u l o s k e l e t a l fitness s c o r e , a v e r a g e counts per minute a n d a v e r a g e M V P A per day. T h e calculation of I C C for e a c h variable w a s a s follows:  =  S u m of s q u a r e s for b e t w e e n s c h o o l differences ( S u m of s q u a r e s for b e t w e e n s c h o o l + within s c h o o l differences)  D a t a w e r e a n a l y z e d using S P S S statistical software, W i n d o w s V e r s i o n 14.0. S i g n i f i c a n c e w a s s e t at p< 0.05 for all statistical a n a l y s e s .  36 C H A P T E R IV Results 4.1 G e n e r a l S u b j e c t C h a r a c t e r i s t i c s Descriptive v a r i a b l e s for b o y s a n d girls that remained in the final a n a l y s i s are s u m m a r i z e d in T a b l e 4.1.  Of the 170 children u s e d in the a n a l y s e s , 1 7 . 6 % w e r e  classified a s overweight ( 5 6 . 7 % b o y s a n d 6 6 . 7 % A s i a n ) a n d 3 . 5 % w e r e classified a s o b e s e ( 5 0 % b o y s a n d 6 6 . 7 % A s i a n ) using a g e a n d s e x - s p e c i f i c cut-off v a l u e s (119).  T a b l e 4.1. M e a n s a n d S D s of participant characteristics. B o d y M a s s lndex=BMI, S B P = s y s t o l i c blood p r e s s u r e , D B P = d i a s t o l i c blood pressure, M S K S c o r e = m u s c u l o s k e l e t a l fitness s c o r e . N  Boys  N  Girls  Age (years)  79  10.0 ± 0 . 6  91  10.0 ± 0 . 6  Height (cm)  79  141.3 ± 7 . 6  91  141.2 ± 7 . 5  Weight (kg)  79  36.6 ± 8.0  91  35.3 ± 7 . 7  BMI (kg/m )  79  18.2 ± 2 . 8  91  17.6 ± 2 . 6  S B P (mmHg)  77  98.2 ± 7.0  91  96.9 ± 9 . 1  D B P (mmHg)  77  63.1 ± 7 . 1  91  62.0 ± 8.9  Heart Rate (bpm)  76  87.2 ± 10.9  89  87.7 ± 12.7  Total Laps  79  25.1 ± 14.8  91  2 1 . 3 ± 11.6  M S K Score  79  -.0434 ± 1.4677  91  -.0336 ± 1.8757  z  T h e r e w e r e significant correlations b e t w e e n weight status, the m u s c u l o s k e l e t a l fitness s c o r e , total laps run (Leger shuttle run test) a n d P A o u t c o m e variables (see T a b l e 4.2).  T h e r e w e r e no significant correlations b e t w e e n v a s c u l a r health a n d P A or  weight status a n d P A . D a t a w e r e e x a m i n e d for normal distribution a n d tests to detect s k e w n e s s or kurtosis w e r e c o m p l e t e d . M i n u t e s per d a y of bouted activity, total l a p s a n d B M I w e r e negatively s k e w e d a n d therefore log transformed. T h e curl-up a n d p u s h - u p data demonstrated a o n e - s i d e d distribution a n d underwent reciprocal transformation.  37  T a b l e 4.2. Significant correlations b e t w e e n anthropometric, fitness a n d physical activity variables. (**) d e n o t e s p < 0 . 0 0 1 , (*) d e n o t e s p < 0.05 M S K S c o r e = m u s c u l o s k e l e t a l c o m p o s i t e s c o r e , C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity  CPM  MVPA  Total Laps NS  NS  NS  Height  1  .752  .461**  MSK Score NS  Weight  .752**  1  .270**  NS  -.192*  NS  NS  Age  .461**  .270**  1  NS  NS  -.177*  -.306**  MSK Score Total Laps CPM  NS  NS  NS  1  .507**  .171*  .152*  NS  -.192*  NS  .507**  1  .221**  .189*  NS  NS  -.177*  .171*  .221**  1  .925**  MVPA  NS  NS  -.306**  .152*  .189*  .925**  1  Height  Age  Weight  T h e r e w e r e no differences o b s e r v e d in weight status, v a s c u l a r or health-related physical fitness v a r i a b l e s b e t w e e n the groups w h o met the inclusion criteria for P A data and t h o s e w h o did not (in both the girls a n d the boys). T h e r e w e r e 52 b o y s and 47 girls w h o did not h a v e valid P A data of w h i c h 3 8 % a n d 5 7 % , respectively, w e r e C a u c a s i a n . T h e r e w a s no significant difference in weight status, v a s c u l a r o r health-related physical fitness b e t w e e n b o y s a n d girls.  4.2 P h y s i c a l Activity P a t t e r n s O n a v e r a g e , the monitors w e r e worn for 13.5 ± 1.1 h o u r s p e r d a y with b o y s a c c u m u l a t i n g 4 0 8 4 9 9 . 7 ± 1 0 6 8 3 1 . 0 a n d girls a c c u m u l a t i n g 3 4 3 8 0 7 . 8 ± 106912.8 counts per d a y (see T a b l e 4 . 3 for P A o u t c o m e variables in b o y s a n d girls). B o y s obtained significantly more counts per minute o n a v e r a g e than girls (p < 0.001), a v e r a g e M V P A per d a y (p < 0.001), a v e r a g e M V P A per w e e k e n d (p < 0.03) a n d w e e k d a y (p < 0.001), a n d a c c u m u l a t e d m o r e bouted m i n u t e s of M V P A than girls (p < 0.001). T h e r e w a s no significant difference in minutes of s p o r a d i c M V P A between the g e n d e r s . In both g e n d e r s , significantly more M V P A o c c u r r e d on the w e e k d a y s than on w e e k e n d d a y s (p < 0.001). O n e child (Asian male) met C a n a d a ' s P h y s i c a l Activity G u i d e l i n e s for C h i l d r e n a n d Y o u t h .  38  T a b l e 4 . 3 . M e a n s a n d S D s of all P A outcome variables. A v g = a v e r a g e , M V P A = m o d e r a t e - t o - v i g o r o u s physical activity, P E = p h y s i c a l education.  B o y s (N = 79)  Girls (N = 91)  Avg Hours of W e a r Per Day  13.5 ± 1.12  13.4 ± 1 . 1  Avg Counts Per Day  408499.7 ± 106831.0  343807.8 ± 106912.8  Avg Counts Per Minute  503.6 ± 122.7  429.8 ± 140.7  Avg Minutes of M V P A Per Day  133.9 ± 3 3 . 9  113.5 ± 3 5 . 9  Avg Minutes of M V P A Per  149.0 ± 3 7 . 4  124.6 ± 4 0 . 4  112.7 ± 4 5 . 0  98.4 ± 43.9  104.7 ± 2 4 . 0  98.0 ± 27.8  29.2 ± 20.9  15.5 ± 12.5  65.1 ± 2 1 . 0  52.4 ± 17.5  Total Minutes of Recess M V P A  5.1 ± 4 . 3  3.4 ± 3 . 1  Total Minutes of Lunchtime  16.5 ± 7 . 4  12.6 ± 5 . 2  5.3 ± 6 . 2  6.5 ± 7 . 1  Weekday Avg Minutes of M V P A Per Weekend Day Avg Minutes of Sporadic M V P A Per Day Avg Minutes of Bouted M V P A Per Day Total Minutes of School Day MVPA  MVPA Total Minutes of P E M V P A  In b o y s , 2 6 . 7 % of morning r e c e s s (5.1 ± 4.3 minutes) w a s s p e n t in M V P A , 3 5 . 4 % of lunch hour (16.5 ± 7.4 minutes), and only 1 3 . 1 % of P E (5.3 ± 6.2 minutes). Girls a c c u m u l a t e d M V P A for 1 8 . 3 % of r e c e s s time (3.4 ± 3.1 minutes), 2 7 . 1 % of lunch hour (12.6 ± 5.2 minutes) a n d 1 6 . 0 % of P E (6.5 ± 7.1 minutes) in M V P A . Total minutes of M V P A during the s c h o o l d a y a c c o u n t e d for 2 4 . 6 % (65.1 ± 2 1 . 0 minutes) and 2 0 . 8 % (52.4 ± 17.5 minutes) of the total s c h o o l d a y in b o y s and girls, respectively.  4.3 Ethnic Differences in P h y s i c a l Activity and H e a l t h - R e l a t e d P h y s i c a l Fitness  39 C a u c a s i a n girls ran significantly more laps than A s i a n girls in the L e g e r shuttle run (p < 0.01), h a d significantly higher counts per minute (p < 0.001), a n d a v e r a g e minutes of M V P A per d a y (p < 0.001). T h e r e w a s no significant ethnic difference in the m u s c u l o s k e l e t a l fitness s c o r e for girls. C a u c a s i a n b o y s ran significantly more laps than A s i a n b o y s in the L e g e r shuttle run (p < 0.01), had significantly higher counts per minute (p < 0.03) a n d a c h i e v e d significantly higher s c o r e s on the m u s c u l o s k e l e t a l fitness s c o r e (p < 0.01). T h e r e w e r e no significant ethnic differences in the a v e r a g e minutes of M V P A per d a y in b o y s . Initially, the difference in e a c h individual c o m p o n e n t of m u s c u l o s k e l e t a l fitness w a s e x a m i n e d b e t w e e n ethnic g r o u p s . D u e to the large variation in s c o r e s between both male a n d f e m a l e ethnic g r o u p s , the homogeneity of v a r i a n c e tests w e r e not met for p u s h - u p s a n d s i t - a n d - r e a c h in girls a n d curl-ups a n d grip strength in b o y s (see Appendix J).  4.4 R e g r e s s i o n A n a l y s i s T h e v a r i a n c e in health-related physical fitness (total laps run a n d the m u s c u l o s k e l e t a l fitness s c o r e w e r e e x a m i n e d separately) e x p l a i n e d by P A (average counts per minute a n d M V P A per day) w a s e x a m i n e d by entering the following independent v a r i a b l e s sequentially into a hierarchical r e g r e s s i o n : 1) a g e , height, weight, 2) ethnicity, 3) c o u n t s per minute a n d , 4) M V P A per d a y . R e s u l t s are presented in T a b l e s 4.4 - 4.5 (girls) a n d T a b l e s 4.6 - 4.7 (boys). In girls, a g e , height, a n d weight a c c o u n t e d for 1 1 . 2 % of the v a r i a n c e in total laps run in the L e g e r shuttle run (p < 0.01), with ethnicity contributing another 8 . 3 % (p < 0.03). Neither counts per minute or M V P A per d a y contributed significantly to the m o d e l . N o n e of the i n d e p e n d e n t variables significantly predicted the m u s c u l o s k e l e t a l c o m p o s i t e s c o r e in girls. In b o y s , a g e , height, a n d weight a c c o u n t e d for 1 9 . 7 % of the v a r i a n c e in total laps run (p < 0.001) a n d ethnicity a c c o u n t e d for 7 . 8 % more (p < 0.01). Neither counts per minute or M V P A per d a y significantly contributed to the m o d e l . Ethnicity w a s the only independent variable that significantly contributed to the prediction (8.4%) of the m u s c u l o s k e l e t a l c o m p o s i t e s c o r e (p < 0.01). T w o other c o m p o s i t e s c o r e s w e r e created to: 1) e x a m i n e the relationship b e t w e e n the combination of m u s c u l o s k e l e t a l fitness c o m p o n e n t s a n d total laps run to P A and 2) e x a m i n e the relationship of a c o m p o s i t e s c o r e of all health-related p h y s i c a l fitness  40  c o m p o n e n t s a n d P A ( s e e A p p e n d i x J). T h e correlation b e t w e e n both of t h e s e fitness s c o r e s a n d P A w a s lower than the individual c o m p o n e n t s of health-related physical fitness a n d P A a n d the correlation b e t w e e n P A a n d the m u s c u l o s k e l e t a l c o m p o s i t e s c o r e reported. T h e factor loadings of the individual c o m p o n e n t s within the final s c o r e c a n explain this. F o r e x a m p l e , in the c o m p o s i t e s c o r e that included all health-related physical fitness c o m p o n e n t s , BMI a n d W C had the highest factor loadings. B o d y m a s s index a n d W C h a d very w e a k a n d non-significant correlations to P A . W h e n t h e s e more heavily-weighted c o m p o n e n t s w e r e a d d e d to the rest of the s c o r e s , the c o m p o n e n t s (such a s total laps) that w e r e more highly correlated to P A b e c a m e diluted. Forward s t e p w i s e r e g r e s s i o n w a s a l s o u s e d to e x a m i n e the relationship b e t w e e n P A and health-related p h y s i c a l fitness. T h e s a m e independent variables that w e r e entered into the hierarchical r e g r e s s i o n (height, weight, a g e , ethnicity, M V P A per d a y and counts per minute) w e r e entered simultaneously into the s t e p w i s e equation. In girls, weight a n d ethnicity significantly predicted fitness a n d in b o y s , height, weight, and ethnicity predicted fitness ( s e e A p p e n d i x J ) .  4.5 Intraclass Correlation Intraclass correlations w e r e a s follows: 0.27, 0.07, 0.07, a n d 0.07 for total laps run, m u s c u l o s k e l e t a l c o m p o s i t e s c o r e , a v e r a g e counts per minute a n d a v e r a g e M V P A per day, respectively.  41  T a b l e 4 . 4 . R e s u l t s of hierarchical multiple regression m o d e l for cardiorespiratory fitness (total laps run in the L e g e r Shuttle R u n test) in A s i a n a n d C a u c a s i a n girls. C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity. Adjusted R  R Change  Variable in  Standardized  Unstandardized  Model  Beta  Beta  Total Laps  Height  .349  .025  0.112  0.141  Run  (p < 0.02) -.461  -.033  0.112  0.141  -.258  -.234  0.112  0.141  -.250  -.275  0.189  0.083  .369  .001  0.179  0.000  -.358  -.005  0.181  0.011  Fitness  Weight  2  2  (p < 0.002) Age (p < 0.03) Ethnicity (p < 0.03) CPM (p < 0.28) MVPA (p < 0.28)  T a b l e 4 . 5 . R e s u l t s of hierarchical multiple regression m o d e l for m u s c u l o s k e l e t a l fitness in A s i a n a n d C a u c a s i a n b o y s . C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity. R  Change  Variable in  Standardized  Unstandardized  Adjusted  Model  Beta  Beta  R  Musculoskeletal  Height  .189  .044  -0.008  0.025  Score  (p < 0.26) -.030  -.007  -0.008  0.025  .001  .003  -0.008  0.025  -.105  -.368  0.014  0.033  -.016  .000  0.045  0.040  .259  .013  0.040  0.006  Fitness  Weight  2  2  (p < 0.85) Age  (p < 0.99) Ethnicity (p < 0.37) CPM (p < 0.96) MVPA  (p < 0.46)  42 T a b l e 4.6. R e s u l t s of hierarchical multiple regression m o d e l for cardiorespiratory fitness (total laps run in the L e g e r Shuttle R u n test) in A s i a n a n d C a u c a s i a n b o y s . C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity. R  Change  Variable in  Standardized  Unstandardized  Adjusted  Model  Beta  Beta  R  Total Laps  Height  .459  .036  0.164  0.197  Run  (p<0.01) -.614  -.045  0.164  0.197  -.055  -.053  0.164  0.197  -.274  -.322  0.235  0.078  -.069  -.001  0.233  0.008  .187  .003  0.229  0.006  Fitness  Weight  2  2  (p< 0.001) Age (p < 0.64) Ethnicity (p<0.01) CPM (p < 0.78) MVPA (p < 0.45)  T a b l e 4 . 7 . R e s u l t s of hierarchical multiple r e g r e s s i o n m o d e l for m u s c u l o s k e l e t a l fitness (composite s c o r e ) in A s i a n a n d C a u c a s i a n b o y s . C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity. R  Change  Variable in  Standardized  Unstandardized  Adjusted  Model  Beta  Beta  R  Musculoskeletal  Height  .362  .071  0.048  0.084  Score  (p < 0.06) -.248  -.046  0.048  0.084  -.151  -.370  0.048  0.084  -.340  -1.008  0.123  0.084  -.225  -.003  0.129  0.017  .089  .004  0.118  0.001  Fitness  Weight  2  2  (p<0.16) Age (p < 0.23) Ethnicity (p < 0.004) CPM (p < 0.40) MVPA (p < 0.74)  43  CHAPTER V  Discussion 5.1 P h y s i c a l Activity Patterns in Children  5.1.1 G e n e r a l P h y s i c a l Activity Patterns T h e g e n e r a l trends in our data are consistent with p u b l i s h e d literature (40, 120). In boys, almost 8 0 % of a v e r a g e M V P A per day is spent in s p o r a d i c activity a n d in girls almost 9 0 % , illustrating the highly transitory nature of children's P A . Similar to our results, S l e a p a n d W a r b u r t o n (40) a n d E p s t e i n a n d c o l l e a g u e s (51) reported that children a c c u m u l a t e d approximately two hours per d a y of M V P A , h o w e v e r very little of this time w a s spent in s u s t a i n e d bouts of activity.  Significantly more activity occurred  throughout the w e e k d a y s a s c o m p a r e d to the w e e k e n d d a y s . In boys, approximately 150 minutes of M V P A per d a y w e r e a c h i e v e d on the w e e k d a y c o m p a r e d to 115 minutes on the w e e k e n d d a y . T h e a v e r a g e accumulated amount of M V P A per d a y on the w e e k d a y s w a s 125 minutes in girls c o m p a r e d to 100 minutes o n the w e e k e n d . R e c o m m e n d a t i o n s from British C o l u m b i a and the United S t a t e s m a n d a t e that 5 0 % of P E time s h o u l d be d e d i c a t e d to active time (43, 121). Stratton a n d Mullen (122) e x t e n d e d t h e s e r e c o m m e n d a t i o n s with the s u g g e s t i o n that r e c e s s time should a l s o consist of 5 0 % active time. W e found that total minutes of M V P A during the s c h o o l day a c c o u n t e d for 2 4 . 6 % a n d 2 0 . 8 % of the total s c h o o l d a y in b o y s a n d girls, respectively. In boys, 2 6 . 7 % of morning r e c e s s w a s spent in M V P A a n d in girls, 1 8 . 3 % . During lunch hour (which i n c l u d e s both a lunch a n d r e c e s s time) b o y s s p e n t 3 4 . 5 % of the time in M V P A a n d girls s p e n t 2 7 . 1 % . During P E girls a c c r u e d M V P A for 1 3 . 1 % of c l a s s and b o y s 1 6 . 0 % . T h e b o y s are recording a similar n u m b e r of minutes of M V P A during r e c e s s a n d P E d e s p i t e P E being twice the length of r e c e s s . T h i s indicates that b o y s participate in greater a m o u n t s of P A during free play times a s o p p o s e d to structured c l a s s time d e d i c a t e d to P A . O u r data s h o w s that children in V a n c o u v e r are not meeting the r e c o m m e n d a t i o n s for activity participation during either P E or r e c e s s times. In the U.K., p e r c e n t a g e time o b s e r v e d in M V P A at r e c e s s w a s 3 2 . 9 % in b o y s a n d 2 5 . 3 % in girls (44). T h e s e p e r c e n t a g e s are higher than our o b s e r v a t i o n s but still far from achieving the guidelines. T h e s e results b e c o m e e v e n more alarming considering that it  44  is during t h e s e s c h o o l break times w h e n M V P A h a s b e e n m o s t c o m m o n l y s e e n in children (40). S c h o o l s in California report that 4 0 % of a 3 0 minute P E c l a s s is d e d i c a t e d to M V P A (123), a n d although this is still below r e c o m m e n d e d levels, it is m u c h higher than that reported in British C o l u m b i a . W e found that 1 3 % (boys) a n d 1 6 % (girls) of the allotted P E time w a s spent in M V P A w h e r e a s P a r c e l et a l . (42) estimated that children w e r e aerobically active for 6 % of P E time. U s i n g p e d o m e t e r s to a s s e s s P A , it w a s found that the s t e p s a c c u m u l a t e d during P E a c c o u n t e d for 8 a n d 1 1 % of total s t e p s per d a y in b o y s a n d girls, respectively (124). It is clear that P E c l a s s is not providing sufficient opportunity for P A a n d insufficient P A is occurring during r e c e s s . R e c e n t r e s e a r c h h a s s h o w n that children w h o w e r e least active during the s c h o o l d a y w e r e a l s o the least active after s c h o o l hours and on the w e e k e n d d a y s (61). T h i s information highlights the n e c e s s i t y of s c h o o l - b a s e d interventions to s u p p l e m e n t regular s c h o o l d a y activity a n d to provide children with the skills to be m o r e active throughout the w h o l e day.  5.1.2 G e n d e r Differences in P h y s i c a l Activity a n d H e a l t h - R e l a t e d P h y s i c a l Fitness W e found that b o y s participated in significantly more M V P A per d a y a n d on a v e r a g e , had higher counts per minute (indicating more time spent in P A of higher intensity) than girls. G e n d e r differences in P A h a v e b e e n fairly well-established with b o y s displaying higher levels of P A than girls of the s a m e a g e (11, 34, 36, 3 8 , 51) a n d b o y s s p e n d i n g significantly m o r e time in vigorous P A than girls (11, 39, 52). E v i d e n c e h a s a l s o s h o w n that b o y s participate in a greater number of longer bouts of higher intensity activity than girls (39). Specifically in this investigation, b o y s a c c u m u l a t e d d o u b l e the amount of bouted M V P A minutes than did girls. R o w l a n d s et a l . (53) s u g g e s t e d that vigorous intensity P A m a y explain the differences in activity that o c c u r s b e t w e e n g e n d e r s . In addition, our results a l s o imply that time spent in bouted M V P A a l s o a c c o u n t s for the disparity b e t w e e n b o y s a n d girls s i n c e w e found no significant difference b e t w e e n a v e r a g e minutes of s p o r a d i c M V P A per day. T h i s information s u g g e s t s that b o y s m a y be more likely than girls to participate in structured, p l a n n e d P A at high intensities. B o y s generally perform better in cardiorespiratory fitness tests (26, 2 7 , 6 0 , 125) a n d in m u s c u l o s k e l e t a l fitness tests (26, 98) than a g e - m a t c h e d girls. A l t h o u g h our observations w e r e not found to be significant, there w a s a trend for b o y s to complete  45  more laps in the shuttle run test. O u r group previously reported no significant differences in c a r d i o v a s c u l a r fitness between b o y s a n d girls in a similar group of participants (67). T h e results of other studies m a y not b e directly c o m p a r a b l e to the present study d u e to differences in cardiorespiratory a n d m u s c u l o s k e l e t a l tests and participant characteristics.  5.1.3 P h y s i c a l Activity G u i d e l i n e s O u r d a t a from V a n c o u v e r is e v e n more alarming than that reported in the 2 0 0 7 Report C a r d o n P h y s i c a l Activity for Children & Y o u t h . T h e y found that only 9 % of C a n a d i a n children met the guidelines while in our study, only o n e child met the guidelines of 90 minutes of M V P A per day. D e s p i t e b o y s participating in approximately 134 minutes a n d girls a c c u m u l a t i n g 114 minutes of M V P A per d a y , only 30 and 15 minutes of a v e r a g e M V P A per d a y in b o y s a n d girls, respectively w a s a c c u m u l a t e d in activities lasting 5 or more minutes in duration. In other w o r d s , b o y s on a v e r a g e are only a c c u m u l a t i n g o n e third of the a m o u n t r e c o m m e n d e d a n d girls, o n e sixth. In a study of similarly-aged children, A n d e r s e n et al. (15) reported more positive data, indicating that the top three most active quintiles of children in the U.K. w e r e achieving o v e r 9 0 minutes of activity per d a y in durations of 5 to 10 minutes. Children in the lowest quintile of P A w e r e still accumulating more activity in s u s t a i n e d periods than the children in the present study. R e s u l t s are not directly c o m p a r a b l e d u e to the difference in cut-points a n d e p o c h lengths u s e d b e t w e e n studies. A n d e r s e n et al. (15) u s e d a threshold of 2 0 0 0 c p m from a 1-minute e p o c h to define M V P A w h e r e a s w e u s e d age-specific cut-points d e v e l o p e d by Trost a n d c o l l e a g u e s (118). A n investigation in S w e d e n d e m o n s t r a t e d the effects on a c c u m u l a t e d activity a s s o c i a t e d with using different e p o c h lengths. E p o c h lengths of 5, 10, 2 0 , 4 0 a n d 6 0 s e c o n d s w e r e u s e d a n d minutes spent in 10-minute bouts w e r e c o m p a r e d . N o 10-minute periods of continuous activity w e r e recorded in the 5 a n d 1 0 - s e c o n d bouts h o w e v e r , a l m o s t 3 bouts w e r e recorded using the 1-minute e p o c h (126). T h i s difference is quite dramatic a n d s u g g e s t s that with the short e p o c h that w a s c h o s e n for this study, bouted activity is not a s likely to be o b s e r v e d . Furthermore, the magnitude of the e p o c h effect is amplified in the most highly active children (126) s i n c e the 1-minute e p o c h is k n o w n to dilute the children's v i g o r o u s intensity (38).  46  In addition to varying e p o c h lengths a n d cut-points, there is no c o n s i s t e n c y in the interpretation of results from studies determining children's c o m p l i a n c e with P A guidelines d e p e n d i n g o n w h e t h e r a s s e s s m e n t s are b a s e d o n intermittent, a c c u m u l a t e d or sustained durations of activity. M e t h o d s of P A data acquisition a n d reduction are highly variable (and the latter is rarely reported) a n d c a n h a v e significant effects on the data. In m a n y studies, actual minutes of P A a n d criteria for qualifying d a t a a s a c c e p t a b l e are not p u b l i s h e d . Finally, guidelines u s e d to a s s e s s children's activity level differ b e t w e e n studies (refer b a c k to T a b l e 2.1).  C o m b i n e d , t h e s e limitations in m a k e  c o m p a r i s o n s b e t w e e n s t u d i e s reporting P A difficult. S i n c e s p o r a d i c activity is typical in children of this a g e (31) a n d constitutes s u c h a large p e r c e n t a g e of total M V P A time, it is extremely v a l u a b l e information. Short e p o c h s w e r e u s e d for the collection of the P A data to e n s u r e that the intermittent a n d short bouts of activity w e r e captured (see A p p e n d i x I).  In addition, w e utilized accelerometry  to m e a s u r e P A s o the d a t a obtained is objective a n d is both date a n d t i m e - s t a m p e d . W e are confident that our d a t a provides an accurate representation of p h y s i c a l activity patterns in the population e x a m i n e d . T o determine activity intensity, w e u s e d a g e specific cut-points d e v e l o p e d by a group of influential r e s e a r c h e r s in the field of accelerometry (118). A n investigation comparing the utility of three c o m m o n l y u s e d cutpoints in children d o c u m e n t e d that t h e s e specific cut-points are a b l e to accurately categorize activity into the correct intensity categories (127). In addition, our group a n a l y z e d the P A d a t a with c u s t o m d e s i g n e d software w h i c h a l l o w e d us to e x a m i n e the P A patterns in great detail. F o r e x a m p l e , w e w e r e a b l e to determine the number of M V P A minutes that o c c u r r e d during e a c h s e g m e n t of the s c h o o l d a y a n d w e w e r e a b l e to fractionalize the M V P A minutes to determine the a m o u n t that o c c u r r e d in bouts. Furthermore, d e c i s i o n s regarding inclusion and e x c l u s i o n criteria w e r e b a s e d on the a v e r a g e d a y of a child in our study. T h e a v e r a g e ' o n ' a n d 'off times w e r e calculated for e a c h d a y a n d only t h o s e children w h o w o r e the monitor within t h o s e hours w e r e retained in the a n a l y s i s . A l t h o u g h this d e c r e a s e d our s a m p l e s i z e , it a l s o eliminated bias that might o c c u r with variable w e a r hours. T h e ' o n ' a n d 'off times that w e r e u s e d to determine valid d a y s are normal w e a r hours for the children a n d w e r e not arbitrarily c h o s e n . T h u s , the d a t a p r e s e n t e d is representing what o c c u r s in a n a v e r a g e d a y for the children. Finally, w e e x a m i n e d P A c o m p l i a n c e using the only g u i d e l i n e s available that  47  c o n s i d e r the specific characteristics of P A in children. T h e s e guidelines are b a s e d on expert opinion. T h e available d a t a s u g g e s t i n g that children are not meeting the p h y s i c a l activity guidelines support our first hypothesis. Additional reports s h o w i n g that children are not meeting activity r e c o m m e n d a t i o n s within the s c h o o l d a y p r o v i d e s clear e v i d e n c e that children are not acquiring e n o u g h P A .  5.2 Ethnicity, P h y s i c a l Activity a n d P h y s i c a l F i t n e s s  5.2.1 Ethnic Differences in P h y s i c a l Activity W e found that C a u c a s i a n girls a c c u m u l a t e greater a m o u n t s of higher intensity activity (as indicated by the a v e r a g e counts per minute) than A s i a n girls a n d participated in significantly m o r e M V P A per day.  In a study of 10 year-old A s i a n a n d C a u c a s i a n  girls in V a n c o u v e r , C a u c a s i a n girls e n g a g e d in almost d o u b l e the n u m b e r of extracurricular or sport activities a n d double the amount of l o a d e d activity (defined a s activity that h a s a greater impact than walking) than the A s i a n girls. T h e difference in g e n e r a l activity, a s s e s s e d by the P h y s i c a l Activity Q u e s t i o n n a i r e for C h i l d r e n , w a s only slight (17).  Investigations b a s e d in the United S t a t e s a l s o s h o w e d A s i a n s participating  in l e s s vigorous intensity e x e r c i s e than A n g l o - S a x o n individuals (128) a n d achieving lower s c o r e s o n P A q u e s t i o n n a i r e s (62). G o r d o n - L a r s e n et a l . (34) d i s c o v e r e d that almost 5 0 % of the A s i a n girls in their study e n g a g e d in 2 or l e s s bouts of M V P A per w e e k . Of the 3 ethnic g r o u p s e x a m i n e d , the n o n - H i s p a n i c white f e m a l e s w e r e most likely to participate in M V P A a n d the A s i a n girls w e r e least likely to participate in M V P A . O n l y o n e study from the V a n c o u v e r region did not exhibit a significant difference in P A b e t w e e n the A s i a n a n d C a u c a s i a n girls (18). R e s u l t s from this investigation indicate that A s i a n b o y s participate in l e s s high intensity activity than C a u c a s i a n b o y s . T h e data indicating that there is no difference in total a m o u n t s of a c c u m u l a t e d M V P A per day b e t w e e n A s i a n a n d C a u c a s i a n b o y s is consistent with d a t a p r e s e n t e d by M a c K e l v i e et al. (64) w h o f o u n d , using the P h y s i c a l Activity Q u e s t i o n n a i r e for C h i l d r e n , that there w a s no significant difference in P A b e t w e e n 10 y e a r - old A s i a n a n d C a u c a s i a n b o y s in V a n c o u v e r . In addition, information from the National Longitudinal S t u d y of A d o l e s c e n t Health in the United States reported that in a d o l e s c e n t b o y s , there w a s minimal difference in P A (as m e a s u r e d by self-  48 report) b e t w e e n A s i a n b o y s a n d b o y s of other ethnicities (34). E v i d e n c e from M c K a y et al. (18) V a n c o u v e r - b a s e d study demonstrated that C a u c a s i a n b o y s w e r e significantly more active than their A s i a n p e e r s a n d approximately five times a s m a n y C a u c a s i a n b o y s participated in extracurricular sport activities (18). R e a s o n s for t h e s e disparities could stem from the m e t h o d s utilized to obtain estimates of P A . In our investigation, P A data w a s m e a s u r e d objectively using accelerometry w h e r e a s self-report questionnaires w e r e u s e d in the other studies. T h e benefits of a c c e l e r o m e t r y are demonstrated in our results. In b o y s w e found a difference in the intensity of activity b e t w e e n ethnic g r o u p s in the a b s e n c e of a difference in M V P A per d a y . T h e a c c e l e r o m e t e r detects a c c e l e r a t i o n of the body a n d provides a direct m e a s u r e of P A intensity in counts. It is therefore better able to capture high intensity activity in c o m p a r i s o n to m e a s u r e s of self-report w h i c h w e r e u s e d in the other investigations. T h i s eliminates s o m e of the limitations a n d bias a s s o c i a t e d with self-report a n d m a y be the r e a s o n a difference w a s d e t e c t e d . It is p o s s i b l e that the activity levels of the A s i a n children in our study w e r e underestimated b a s e d on M a c K e l v i e et a l . (17) w h o reported that in g e n e r a l , A s i a n girls living in V a n c o u v e r more c o m m o n l y participate in s w i m m i n g l e s s o n s than other sports. T h e a c c e l e r o m e t e r is not waterproof a n d therefore is not a b l e to be worn for w a t e r - b a s e d activities. Despite this, the difference in P A w a s very highly significant (p < 0.001) indicating that very high a m o u n t s of s w i m m i n g w o u l d n e e d to be a c c u m u l a t e d to a c c o u n t for the difference in PA. Other factors that m a y contribute to w h y A s i a n children are l e s s active than C a u c a s i a n children h a v e b e e n c o n s i d e r e d within the literature. P s y c h o l o g y r e s e a r c h s u g g e s t s that A s i a n children (both male a n d female) p e r c e i v e a lack of control over e n g a g i n g in P A a n d therefore are less likely to participate in P A (129). T h i s lack of control m a y b e d u e to factors s u c h a s being required to allot a greater amount of time to a c a d e m i c e n d e a v o r s (129). F o r e x a m p l e , A s i a n children are twice a s likely a s C a u c a s i a n children to s p e n d time in a c a d e m i c l e s s o n s (i.e., m u s i c l e s s o n s , mathematics, etc.) after s c h o o l a s o p p o s e d to sporting activities (18). Specifically in girls, culture m a y c o n s i d e r s t r e n u o u s activity to be u n a c c e p t a b l e a n d activity is therefore not e n c o u r a g e d (62). S o c i a l factors, s u c h a s parental support or level of activity of the parent(s) m a y a l s o influence P A b e h a v i o u r s in children (130). Positive a s s o c i a t i o n s b e t w e e n parental e n c o u r a g e m e n t of P A a n d children's i m m e d i a t e activity h a v e  49  consistently b e e n s h o w n (131, 132). Statistics C a n a d a reported that A s i a n m e n a n d w o m e n in C a n a d a a l s o a c c u m u l a t e lower levels of P A than C a u c a s i a n m e n a n d w o m e n (16), thus there is the potential for this to influence the level of M V P A in A s i a n children.  5.2.2 Ethnic Differences in H e a l t h - R e l a t e d P h y s i c a l F i t n e s s Limited r e s e a r c h h a s b e e n c o n d u c t e d on the c o m p o n e n t s of health-related physical fitness a n d h o w t h o s e differ b e t w e e n A s i a n and C a u c a s i a n children living in the s a m e g e o g r a p h i c a l location. In the U.K., lower levels of p h y s i c a l fitness in A s i a n a s c o m p a r e d to A n g l o - S a x o n children h a v e b e e n reported (66). M o r e specifically, in Britain, o n e third of children of Indian (South A s i a n ) b a c k g r o u n d w e r e unable to c o m p l e t e the cardiorespiratory test (power output against load at 8 5 % of the m a x i m u m heart rate) utilized in the study. M o r e o v e r , those that did c o m p l e t e the test a c h i e v e d lower s c o r e s than children of other ethnicities (19). This trend w a s the s a m e for both g e n d e r s . A l t h o u g h w e found that A s i a n girls completed significantly f e w e r laps in the L e g e r shuttle run test than C a u c a s i a n girls w e found no difference in the m u s c u l o s k e l e t a l fitness s c o r e b e t w e e n ethnicities in girls. In b o y s , there w a s a significant difference with the C a u c a s i a n b o y s completing more laps and achieving higher m u s c u l o s k e l e t a l fitness s c o r e s than A s i a n b o y s . O u r d a t a supports previous r e s e a r c h from our group demonstrating lower cardiorespiratory fitness in A s i a n b o y s a n d girls (67). Significant correlations b e t w e e n P A , (average counts per minute), a n d total laps run in the L e g e r shuttle run (r = 0.230, p < 0.001) s u g g e s t that t h o s e children w h o participate in higher intensity activity are more likely to obtain a higher s c o r e in the L e g e r shuttle run. Activity at high intensity is thought to contribute more to healthy levels of cardiorespiratory fitness than lower levels of activity (133). In both the b o y s a n d girls, t h o s e of C a u c a s i a n ethnicity h a d significantly greater counts per minute than children of A s i a n ethnicity. In prepubertal children, differences in fitness levels c a n be partially e x p l a i n e d by differences in P A (92). C o n s e q u e n t l y , this m a y be o n e underlying r e a s o n w h y C a u c a s i a n children performed better in the shuttle run test. Other possible r e a s o n s for the difference in cardiorespiratory fitness b e t w e e n ethnic g r o u p s are the s a m e a s s o m e of t h o s e outlined previously a s being r e a s o n s for the difference in P A . A s i a n children are m o r e likely to s p e n d free time e n g a g i n g in activities with a more a c a d e m i c f o c u s than C a u c a s i a n children (18) a n d cultural n o r m s m a y d i s c o u r a g e participation in v i g o r o u s activities w h i c h promote p h y s i c a l fitness (62). Furthermore, if  50  C a u c a s i a n children are participating in more o r g a n i z e d sport (18), they m a y be e n h a n c i n g cardiorespiratory fitness to a greater extent than if they w e r e just being regularly active on their o w n . T h e m u s c u l o s k e l e t a l fitness s c o r e w a s significantly higher in C a u c a s i a n boys than A s i a n b o y s . T h e s a m e r e a s o n s that C a u c a s i a n b o y s c o m p l e t e d more laps in the shuttle run than A s i a n b o y s could explain w h y C a u c a s i a n boys a l s o h a v e a higher m u s c u l o s k e l e t a l fitness s c o r e . T h e C a u c a s i a n girls, d e s p i t e participating in greater a m o u n t s of high intensity activity a n d total P A , a n d completing more laps in the L e g e r shuttle run, did not h a v e a significantly greater m u s c u l o s k e l e t a l fitness s c o r e . D u e to a difference in v a r i a n c e b e t w e e n the C a u c a s i a n a n d A s i a n children (in both b o y s a n d girls) s o m e of the individual c o m p o n e n t s of m u s c u l o s k e l e t a l fitness did not meet the a s s u m p t i o n of h o m o g e n e i t y of v a r i a n c e , (see A p p e n d i x J for statistics). Therefore, the aggregate s c o r e to c o m p a r e m u s c u l o s k e l e t a l fitness b e t w e e n ethnic g r o u p s w a s u s e d . T h e t e c h n i q u e that w a s u s e d weights e a c h of the c o m p o n e n t s b a s e d on their relationship to e a c h other a n d this weighting is u s e d to calculate the final v a l u e of the s c o r e (refer b a c k to s e c t i o n 3.3.5). It is p o s s i b l e that the u s e of this c o m p o s i t e scoring s y s t e m m a s k e d the individual differences of the various m u s c u l o s k e l e t a l fitness c o m p o n e n t s b e t w e e n ethnicities in girls. F o r e x a m p l e , in the formula u s e d , p u s h u p s a n d grip strength w e r e similarly weighted. If the C a u c a s i a n girls c o m p l e t e d more p u s h u p s on a v e r a g e than the A s i a n girls but there w a s no difference in a v e r a g e grip strength s c o r e s , the difference in p u s h u p s c o r e s b e t w e e n ethnicities would be diluted. T h e results revealing differences in P A a n d fitness b e t w e e n A s i a n a n d C a u c a s i a n children support our s e c o n d hypothesis. W e are confident that the significant differences o b s e r v e d b e t w e e n A s i a n and C a u c a s i a n children w e r e not d u e to body s i z e or a g e s i n c e differences r e m a i n e d after weight, height, a n d a g e w e r e entered a s covariates into the A N C O V A . T h e covariates w e r e c h o s e n b a s e d on previous literature or o b s e r v e d relationships in the present dataset. T h e r e is a clearly defined relationship b e t w e e n a g e a n d P A w h e r e b y P A d e c r e a s e s with increasing a g e (37, 38, 46) and this relationship w a s detected in the correlations b e t w e e n a g e a n d P A variables. M o s t w e r e significant a n d negative (r = - 0 . 1 6 0 - (-0.306)). Height w a s u s e d a s a n index of maturity. A s individuals mature, P A d e c r e a s e s (52). Finally, a substantial amount of literature h a s d e m o n s t r a t e d that weight is significantly a n d inversely related to P A (22,  51 74). A l t h o u g h w e found no relationship b e t w e e n weight status a n d P A , it w a s still entered b a s e d on findings in the literature. T o our k n o w l e d g e , this is the first study in C a n a d a using accelerometry to c o m p a r e P A levels b e t w e e n A s i a n a n d C a u c a s i a n children. It is a l s o the first to e x a m i n e differences in m u s c u l o s k e l e t a l fitness between ethnic g r o u p s living in the s a m e g e o g r a p h i c region. It therefore provides extremely important information regarding fitness a n d activity in t h e s e two diverse g r o u p s and will contribute significantly to the limited literature regarding ethnic differences in P A a n d health-related physical fitness a n d P A patterning in children.  5.3 P h y s i c a l Activity a n d P h y s i c a l F i t n e s s  5.3.1 P h y s i c a l Activity a n d M u s c u l o s k e l e t a l F i t n e s s Investigations relating P A to indicators of m u s c u l o s k e l e t a l fitness in children report e q u i v o c a l results (88). Sallis et a l . (26) reported that the combination of a physical activity index (multiple m e a s u r e s of P A w e r e taken a n d c o m b i n e d to create o n e variable) a n d g e n d e r a c c o u n t e d for 9 . 1 % , 6 . 7 % , a n d 5 . 1 % of the v a r i a n c e in pull-ups, sit-ups, s i t - a n d - r e a c h s c o r e s , respectively in fourth-grade children.  In c o m p a r i s o n , P A  did not significantly predict our a g g r e g a t e s c o r e of m u s c u l o s k e l e t a l fitness c o m p o n e n t s in either girls or b o y s . T h e r e w a s little difference in the correlations b e t w e e n the m u s c u l o s k e l e t a l fitness s c o r e a n d the individual c o m p o n e n t s of m u s c u l o s k e l e t a l fitness that w e r e significantly related to P A (push-ups w a s the largest a n d only m u s c u l o s k e l e t a l fitness c o m p o n e n t significantly related to P A ) s o it is unlikely that the u s e of the individual c o m p o n e n t s w o u l d result in substantial differences to the findings reported, (see A p p e n d i x J for statistics). Correlations between the m u s c u l o s k e l e t a l fitness s c o r e a n d P A in the present study w e r e w e a k , but significantly related (r = 0.152 - 0.172, p < 0.05). T h e s e relationships are similar to those reported by K a t z m a r z y k et a l . (25) between M V P A ( m e a s u r e d by self-report) a n d individual c o m p o n e n t s of m u s c u l o s k e l e t a l fitness. O n e study h a s also reported no significant relationship b e t w e e n P A a n d m u s c u l o s k e l e t a l fitness ( a s s e s s e d a s m a x i m a l m u s c l e strength of the legs) in children (125). T h e fitness v a r i a b l e s differ between studies a n d m a y represent slightly different d o m a i n s of m u s c u l o s k e l e t a l fitness, a s did the participants, m a k i n g direct c o m p a r i s o n s  52 difficult a n d p o s s i b l y affecting the results. A l t h o u g h m e a s u r e m e n t of P A w a s more c o m p r e h e n s i v e in t h e investigation by Sallis a n d c o l l e a g u e s (26) a n d provided a m o r e holistic picture of the children's P A patterns, the correlations b e t w e e n individual P A c o m p o n e n t s w e r e quite low. T h e participants in the present investigation w e r e not a n ethnically h o m o g e n o u s group a n d w e had less p o w e r w h i c h could also contribute to the difference.  5.3.2 P h y s i c a l Activity a n d Cardiorespiratory F i t n e s s In contrast to our findings that P A (counts per minute a n d M V P A per day) did not contribute to the prediction of cardiorespiratory fitness in children, previous r e s e a r c h h a s d e m o n s t r a t e d significant findings w h e r e b y P A a c c o u n t s for 10 - 2 1 % of the v a r i a n c e in cardiorespiratory fitness. D e n c k e r a n d c o l l e a g u e s (29) c o n c l u d e d that the combination of m e a n daily P A a n d vigorous P A e x p l a i n e d 1 0 % ( 1 % a n d 9%, respectively) of the v a r i a n c e in V02 eak in a group of 8 to 11 year-old children. Sallis et P  al. (26) reported that the combination of a physical activity index (multiple m e a s u r e s of P A w e r e taken a n d c o m b i n e d to create o n e variable) a n d g e n d e r a c c o u n t e d for 1 1 % of the v a r i a n c e in the mile run test. P a t e et al. (134) a l s o u s e d n u m e r o u s m e a s u r e s of P A c o m b i n e d with a g e a n d g e n d e r a s the independent v a r i a b l e s to a c c o u n t for 2 1 % of the v a r i a n c e in the 1.6-km run/walk test. T h e r e are a variety of r e a s o n s to explain this difference. N o n e of the studies mentioned entered weight into the regression m o d e l . W e i g h t h a d a w e a k but significant correlation to total laps run (r = 0.192, p < 0.05) in the present investigation, significantly contributed to our m o d e l (p < 0.001 in boys a n d p < 0.002 in girls) a n d h a s a n e s t a b l i s h e d relationship to fitness o u t c o m e s in children (125). T h i s information s u g g e s t s that it m a y c o n f o u n d the relationship b e t w e e n P A a n d p h y s i c a l fitness a n d should be a c c o u n t e d for w h e n explaining the v a r i a n c e b e t w e e n t h e s e factors. Participant characteristics a l s o differed; participants of the present study w e r e of two different ethnicities w h e r e a s participants of the other studies w e r e a m o r e h o m o g e n o u s group. In the latter study a s m a l l p e r c e n t a g e of the participants w e r e of different ethnicity than the majority group h o w e v e r , this w a s not a c c o u n t e d for in the statistical a n a l y s e s . Ethnicity contributed significantly in the present investigation, a c c o u n t i n g for 7.8 - 8 . 3 % of the v a r i a n c e in cardiorespiratory fitness independent of height, weight a n d age. Different tests of cardiorespiratory fitness w e r e u s e d in the s t u d i e s h o w e v e r the correlations  53  between M V P A per d a y a n d the aerobic fitness tests u s e d w e r e similar between studies. T h i s s u g g e s t s that the inconsistent results s h o u l d not b e attributed to the m e a s u r e m e n t tools.  5.3.3 P h y s i c a l Activity a n d P h y s i c a l F i t n e s s T h e correlation b e t w e e n the m u s c u l o s k e l e t a l fitness s c o r e a n d total laps run (r = 0.507, p < 0.001) is s u g g e s t i v e that the m u s c u l o s k e l e t a l fitness s c o r e m a y be a better predictor of cardiorespiratory fitness (or v i s e versa) than m e a s u r e s of P A . ( S e e A p p e n d i x J , for statistics). P h y s i c a l activity is a b e h a v i o u r (7) a n d is therefore prone to variation (36) a n d influence from n u m e r o u s environmental, cultural (7) a n d social situations. L e v e l s of P A m a y be transient a n d h e n c e , more difficult to relate to a variable or condition at o n e time period. P h y s i c a l fitness is a physiological state (7) or attribute (125), m a k i n g it a more stable entity a n d less prone to variation a n d influence from external factors. P h y s i c a l fitness is thought to d e v e l o p a s a result of prolonged P A . A l t h o u g h fitness d o e s c h a n g e , m e a s u r e m e n t at o n e time point m a y b e more likely to accurately represent the physiological state of a n individual. T h i s is indicated by tracking s t u d i e s w h i c h s h o w that physical fitness h a s higher inter-age correlations a n d more stability over time than indications of P A (7). M o r e o v e r , a recent tracking study in children reported that w h e n s o u r c e s of variation are controlled, results s h o w e d moderate stability of P A (120), thereby demonstrating its m o r e variable nature. F a c t o r s s u c h a s biological a n d behavioural d o m a i n s of c h a n g e a s s o c i a t e d with normal growth a n d maturation, environmental or cultural settings in w h i c h subjects w e r e raised (25), g e n e t i c s (135), diet, a n d motivational (26) or p s y c h o s o c i a l a s p e c t s have also b e e n s u g g e s t e d a s contributors to the v a r i a n c e in p h y s i c a l fitness.  5.3.4 P h y s i c a l Activity a n d W e i g h t Status T h e r e is a n i n c r e a s i n g a m o u n t of e v i d e n c e in the literature demonstrating that body composition, a s s e s s e d either by BMI or percentage fat, is inversely correlated with habitual P A (20, 2 2 , 2 7 , 74). W e found no significant relationship b e t w e e n any P A variables a n d indices of weight status (BMI and W C ) a n d no trends w e r e evident in the data.  P r e v a l e n c e of overweight in this dataset w a s 6 % lower in girls a n d 1 2 % lower in  b o y s than previously p u b l i s h e d reports during the pilot p h a s e of this project (136). T h u s , there m a y not h a v e b e e n sufficient n u m b e r s of overweight children to detect a  54 difference in P A , e s p e c i a l l y s i n c e the P A data w a s quite variable. Alternatively, the overweight children in the s a m p l e m a y be a s active a s normal weight children. In support of our d a t a , o n e of the major findings in a study by G r u n d et a l . (125) w a s that there are no differences in P A b e t w e e n normal weight, overweight a n d o b e s e children. T h e m e a s u r e m e n t tools u s e d should not h a v e contributed to the difference in results between our study a n d t h o s e that did report a significant difference. Indices of weight status u s e d in this investigation (BMI) have b e e n found to be inversely related to P A levels in other cohorts using a variety of tools for P A a s s e s s m e n t . It is p o s s i b l e that in this cohort of children, dietary factors m a y contribute more significantly to the d e v e l o p m e n t of overweight in children, or overweight children m a y b e e n g a g i n g in more P A a s a form of weight control (26). Alternatively (or additionally), in overweight or o b e s e individuals, the a c c e l e r o m e t e r is further from the b o d y ' s centre of gravity than on a normal weight individual. T h i s results in the a c c e l e r o m e t e r e x p e r i e n c i n g greater acceleration for a n y g i v e n movement. It is p o s s i b l e that in the o b e s e children, the a c c e l e r o m e t e r w a s recording e x c e s s i v e m o v e m e n t w h i c h m a y contribute to the higher PA.  5.3.5 P h y s i c a l Activity in Relation to V a s c u l a r Health In normal weight children, P A m a y have little effect o n v a s c u l a r health a s indicated by previous investigations that reported no significant findings (14, 20). W h e n body weight is a c c o u n t e d for, s t u d i e s that did report lower B P v a l u e s in more active children found that the relationship d i s a p p e a r e d (12). C h i l d r e n with lower P A h a d greater body fat w h i c h w a s r e s p o n s i b l e for the high B P v a l u e s (12). Alternatively, the detrimental effects of a n inactive lifestyle on the v a s c u l a r s y s t e m m a y not be a d v a n c e d e n o u g h to be detected by a B P m a c h i n e . W e recently revealed that P A a c c o u n t s for 6 % of the v a r i a n c e in s m a l l artery c o m p l i a n c e a s m e a s u r e d by arterial tonometry (see A p p e n d i x G ) s u g g e s t i n g that the u s e of a d e v i c e more sensitive to blood v e s s e l c h a n g e m a y be better able to e s t a b l i s h this relationship. A l t h o u g h the relationships b e t w e e n P A a n d the c o m p o n e n t s of health-related physical fitness did not support our third hypothesis, our results contribute important information to the existing literature. V a r i o u s statistical tests w e r e completed to thoroughly e x a m i n e the d a t a . Within our regression a n a l y s e s w e controlled for factors (height, weight, a g e and ethnicity) known to contribute to the relationship between P A  and p h y s i c a l fitness a n d w e are therefore confident in the d a t a w e are reporting. T h e fitness m e a s u r e s utilized in the present investigation are rigorous, are c o m m o n l y u s e d in children (115), a n d provide pertinent information regarding fitness, e s p e c i a l l y s i n c e w e utilized a variety of health-related physical fitness tests to obtain a c o m p r e h e n s i v e profile of the children. A s h a s previously b e e n mentioned in the d o c u m e n t , the a c c e l e r o m e t e r is a sensitive a n d objective tool that is ideal for P A m e a s u r e m e n t in children. W e did not find P A to be a significant predictor of fitness in children h o w e v e r our results s u g g e s t that m u s c u l o s k e l e t a l fitness m a y be a stronger predictor of cardiorespiratory fitness than P A .  5.4 Future Directions This study p r o v i d e s important baseline information for A S ! B C to w h i c h the effects of the intervention c a n be c o m p a r e d . Follow-up investigations m a y provide important e v i d e n c e regarding the contribution of bouted activity to health o u t c o m e s , the implications a s s o c i a t e d with P A patterning, and b e t w e e n ethnic g r o u p s , detect w h e r e the difference in activity is occurring. Further exploration of the relationship between m u s c u l o s k e l e t a l a n d cardiorespiratory fitness is a l s o w a r r a n t e d .  5.5 Limitations T h e method of P A m e a s u r e m e n t a n d protocol of obtaining habitual P A data in this investigation is b a s e d o n the a s s u m p t i o n that children's P A habits are relatively constant a n d that w e are a b l e to accurately capture this constant level of P A in only a few d a y s . D u e to the i m m e n s e interest in P A patterning in children, there h a s recently b e e n substantial r e s e a r c h in the n u m e r o u s s o u r c e s of natural variation in this behaviour. K r i s t e n s e n et a l . (36, 120) determined s e v e r a l variations that could significantly affect P A levels in 8 to 10 year-olds a n d M a t t o c k s et a l . (48) c o n c l u d e d that intra-individual variation a n d s e a s o n a l variation w e r e substantial. S i n c e w e are estimating habitual P A from o n e time-point, there is the potential for variation error within our data. F o r e x a m p l e , data collection o c c u r r e d o v e r the months of early N o v e m b e r to early February. In the month of J a n u a r y the city of V a n c o u v e r e x p e r i e n c e d e x c e s s i v e a m o u n t s of rain. P r e v i o u s literature h a s d e m o n s t r a t e d that children are m o r e active during the more pleasant months of the y e a r (36) s o during this time period, children m a y h a v e h a d lower P A levels than normal. T h i s variation m a y  56  partially explain w h y w e found no relationship b e t w e e n P A a n d health-related physical fitness. T h e I C C w a s u s e d to estimate the effects of s c h o o l o n the P A a n d health outcome m e a s u r e s u s e d in the a n a l y s i s . F o r total laps run the I C C w a s 0.27 s u g g e s t i n g that there w a s substantial effect of the s c h o o l . T h e variation m a y be d u e to the s c h o o l environment or it m a y indirectly be d u e to the community the s c h o o l is in (61). T h e I C C w a s low (0.07) for the other c o m p o n e n t s indicating that there w a s more variation between the participants than b e t w e e n the s c h o o l s in the data.  5.6 C o n c l u s i o n s O n l y o n e child in the present investigation met the r e c o m m e n d a t i o n s of C a n a d a ' s P h y s i c a l Activity G u i d e l i n e s for C h i l d r e n . M o r e o v e r , children are not meeting activity level r e c o m m e n d a t i o n s during the s c h o o l day. L o w levels of M V P A s u g g e s t that m a n y children in V a n c o u v e r m a y be at risk for poor health d u e to insufficient P A . O u r results d e m o n s t r a t e d that C a u c a s i a n children had higher levels of P A a n d physical fitness than A s i a n children. L o w levels of P A a n d low fitness levels are important modifiable risk factors for c a r d i o v a s c u l a r d i s e a s e risk a n d are a s s o c i a t e d with various health c o m p l i c a t i o n s . T h e lower levels of P A a n d fitness in A s i a n children indicate that this ethnic group m a y be a vulnerable group at a higher risk for a s s o c i a t e d c a r d i o v a s c u l a r a n d health complications with increasing a g e . P h y s i c a l activity w a s not a significant predictor of fitness in this cohort of children. O u r results s u g g e s t that m u s c u l o s k e l e t a l fitness m a y be a m o r e powerful predictor of cardiorespiratory fitness (and v i s e versa). 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C o l e T J , B e l l i z z a M C , F l e g a l K M , Dietz W H . E s t a b l i s h i n g a standard definition for child overweight a n d obesity worldwide: international study. Br M e d J 2000(320):1-6.  120.  K r i s t e n s e n P , Moller N, K o r s h o l m L, W e d d e r k o p p N , A n d e r s e n L, Froberg K. T r a c k i n g of objectively m e a s u r e d physical activity from childhood to a d o l e s c e n c e : T h e E u r o p e a n youth heart study. S c a n d J M e d S c i S p o r t s 2 0 0 7 .  121.  S e r v i c e s U S D o H a H . Healthy P e o p l e 2 0 1 0 : understanding and improving health. Washington: D H H S ; 2000.  122.  Stratton G , M u l l e n E . T h e effect of playground m a r k i n g s o n the children's p h y s i c a l activity levels. R e v Port C i e n e Desporto 2 0 0 3 ; 3 : S 1 3 7 .  123.  R e s e a r c h Alf. Effects of outdoor education p r o g r a m s for children in California. 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BC Consent Form for Families Please read the following with your child, and if you and your child would like to participate please sign the attached form and return the signed form in the stamped, addressed envelope provided. You may keep the other pages for your records. Procedures. Y o u r child's participation i n the Action Schools! B C ( A S ! B C ) Research Study w i l l involve two in-school testing sessions i n the Fall and Spring o f the next two school years. A l l children w i l l participate i n the Anthropometry and Questionnaire components and a smaller random sample o f students w i l l participate i n the Cardiovascular Health and Musculoskeletal Fitness component. 1.  Anthropometry: Measures o f height, weight and calf and waist circumference w i l l be taken. Total Time - 10 minutes: Fall and Spring.  2.  Questionnaires: Y o u r child w i l l be assisted i n the completion o f questionnaires that w i l l assess their physical activity, nutrition, self-esteem and attitudes and perceptions about physical activity. A trained research assistant w i l l discuss the importance o f these assessments with the children. Total Time - 1 hour: Fall, Winter and Spring.  3.  Cardiovascular Health and Musculoskeletal Fitness: W e w i l l evaluate aerobic fitness using a shuttle run in which students repeatedly run 20 meter laps in time with a clearly audible "beep" until they become tired and choose to stop. Musculoskeletal fitness (i.e. muscle strength and power) w i l l be assessed using a hand held dynamometer. A research assistant w i l l provide clear instructions for each procedure to the students. Resting blood pressure and heart rate w i l l be recorded before all fitness procedures. A smaller group o f students (25%) w i l l be recruited for this portion o f the study. Total Time - 45 minutes: Fall and Spring.  Health History Questionnaire: If you and your child agree to participate in the A S ! B C Research Study, you w i l l be asked to complete the attached Health History Questionnaire to determine i f there are any health reasons to exclude your child from the research study and to identify any conditions or medications that may affect study outcomes.  Possible Harms: None.  74  Consent Form - September 2006 Please Jill out both sides of this form and return it in the stamped, addressed envelope provided. Please keep the other pages for your records.  Parent's Consent Statement: I/We  '  the  (Please print the name of one or both parents/guardians)  parents/guardians o f read all  have received and (Please print child'sfirstand last name)  6 pages o f the information letter and consent form and understand the purpose and procedures o f the Action Schools! B C Research Study as described. Please check (S) one. I agree to have my child participate i n the 3-year Action Schools! B C Research Study (anthropometry, questionnaires) with the understanding that m y child may or may not be randomly selected to participate i n the cardiovascular health and musculoskeletal fitness portion of the study.  I do not agree to have my child participate in Action Schools! B C Research Study.  I understand that at any time during the 3-year Action Schools! B C Research Study we w i l l be free to withdraw without jeopardizing any medical management, employment or educational opportunities. I understand the contents o f a l l six pages o f this form and the proposed procedures. I have had the opportunity to ask questions and have received satisfactory answers to all inquiries regarding this program.  Signature of Parent or Guardian  Printed name of the Parent or Guardian signing above  Date  (Continued on other side)  75  Child's Statement: I have talked with m y parents/guardians about the Action Schools! B C Program and Research Study and I understand what I w i l l be asked to do. I understand that i f I want to I can stop being in the research study at any time and I w i l l still be able to participate i n activities at my school. I have had the chance to ask questions and have received satisfactory answers to all o f m y questions.  Signature of Child  Date  Printed name of child  School Name  Grade and Division  78  Action Schools! BC Consent Form for Families  Please read the following with y o u r child, and if you and y o u r child would like to participate please sign the attached f o r m and return the signed form i n the stamped, addressed envelope provided. Y o u may keep the other pages for y o u r records.  Procedures. Y o u r child's participation i n the Action Schools! B C ( A S ! B C ) Research Study w i l l involve two in-school testing sessions i n the Fall and Spring o f the next two school years. A l l children w i l l participate i n the Anthropometry and Questionnaire components and a smaller random sample o f students w i l l participate i n the Cardiovascular Health and Musculoskeletal Fitness and Accelerometer components. 4.  Anthropometry: Measures o f height, weight and calf and waist circumference w i l l be taken. Total Time - 10 minutes: F a l l and Spring.  5.  Questionnaires: Y o u r child w i l l be assisted i n the completion o f questionnaires that w i l l assess their physical activity, nutrition, self-esteem and attitudes and perceptions about physical activity. A trained research assistant w i l l discuss the importance o f these assessments with the children. Total Time - 1 hour: Fall and Spring.  6.  Cardiovascular Health and Musculoskeletal Fitness: W e w i l l evaluate aerobic fitness using a shuttle run i n which students repeatedly run 20 meter laps i n time with a clearly audible "beep" until they become tired and choose to stop. Musculoskeletal fitness (i.e. muscle strength and power) w i l l be assessed using a hand held dynamometer. A research assistant w i l l provide clear instructions for each procedure to the students. Resting blood pressure and heart rate w i l l be recorded before all fitness procedures. A smaller group o f students (25%) w i l l be recruited for this portion o f the study. Total Time - 45 minutes: Fall and Spring.  7.  Accelerometers: We w i l l monitor children's physical activity with accelerometers. Children w i l l wear the accelerometer (on a belt around their waist) from the time they get up until the time they go to bed (approximately 12 hours) for 5 consecutive days. A research assistant w i l l provide clear instructions for how to wear the accelerometer. A small group o f students (25%) who participate i n the cardiovascular component (item 3 above) w i l l be recruited for this portion o f the study. Total time - 45 minutes i n the F a l l for a session on accelerometer instructions. Accelerometers w i l l be worn for 5 days in the F a l l and Spring.  80  Consent Form - September 2006 Please fill out both sides of this form and return it in the stamped, addressed envelope provided. Please keep the other pages for your records.  Parent's Consent Statement:  the  I/We {Please print the name of one or both parents/guardians)  parents/guardians o f read all  have received and {Please print child'sfirstand last name)  6 pages o f the information letter and consent form and understand the purpose and procedures o f the Action Schools! B C Research Study as described. Please check (S) one.  I agree to have my child participate in the 3-year A c t i o n Schools! B C Research Study (anthropometry, questionnaires) with the understanding that m y child may or may not be randomly selected to participate i n the cardiovascular health and musculoskeletal fitness and accelerometer portions o f the study.  I do not agree to have my child participate in Action Schools! B C Research Study.  I understand that at any time during the 3-year Action Schools! B C Research Study we w i l l be free to withdraw without jeopardizing any medical management, employment or educational opportunities. I understand the contents o f all six pages o f this form and the proposed procedures. I have had the opportunity to ask questions and have received satisfactory answers to all inquiries regarding this program.  Signature of Parent or Guardian  Printed name of the Parent or Guardian signing above  Date  (Continued on other side)  81 C h i l d ' s Statement:  I have talked with m y parents/guardians about the Action Schools! B C Program and Research Study and I understand what I w i l l be asked to do. I understand that i f I want to I can stop being in the research study at any time and I w i l l still be able to participate i n activities at my school. I have had the chance to ask questions and have received satisfactory answers to all o f m y questions.  Signature of Child  D  a  Printed name of child  School Name  Grade and Division  t  e  82 The University of British Columbia Office of Research Services Clinical Research Ethics Board-Room Vancouver, BC V5Z 1L8  210, 828 West 10th Avenue,  ETHICS CERTIFICATE OF EXPEDITED APPROVAL: RENEWAL PRINCIPAL INVESTIGATOR: Heather A. McKay  DEPARTMENT:  UBC CREB NUMBER: H02-70537  INSTITUTION(S) WHERE RESEA RCH WILL BE CARRIED OUT: N/A Other locations where the research will be <:onducted:  N/A  CO-INVESTIGATOR(S): Kate Reed Darren Warburton Parti-Jean Naylor Karim Miran-Khan Ryan Rhodes Heather Macdonald SPONSORING AGENCIES: Provincial Health Services Authority - "Action Schools! B C : Hormones & Lipids in Action Schools! B C Children" - "Action Schools! B C " U B C Start-up Funds - "Action Schools! B C " PROJECT TITLE: Action Schools! B C EXPIRY D A T E OF THIS APPROVAL: December 4,2007APPROVAL DATE: December 4, 2006 CERTIFICATION: In respect of clinical trials: 1. The membership of this Research Ethics Board complies with the membership requirements for Research Ethics Boards defined in Division 5 of the Food and Drug Regulations. 2. The Research Ethics Board carries out its functions in a manner consistent with Good Clinical Practices. 3. This Research Ethics Board has reviewed and approved the clinical trial protocol and informed consent form for the trial which is to be conducted by the qualified investigator named above at the specified clinical trial site. This approval and the views of this Research Ethics Board have been documented in writing. The Chair o f the U B C C l i n i c a l Research Ethics Board has reviewed the documentation for the above named project. The research study, as presented i n the documentation, was found to be acceptable on ethical grounds for research involving human subjects and was approved for renewal by the U B C C l i n i c a l Research Ethics Board.  Approval of the Clinical Research Ethics Board by one of: Dr. Bonita Sawatzky, Associate Chair  84  1.2  How long have you lived in North America?  1.3  Where did your family live before moving to North America?  1.4  How would you classify your family ethnically? (i.e., Caucasian-Canadian, Japanese-Canadian, etc.)  Years:  Months:  A B O U T Y O U R CHILD:  Child's birth weight  Circle one:  Grams or  2.0  Nutrition History:  2.1  Who prepares your child's meals (i.e. mother, father, grandmother, nanny)?  2.2  Does your child drink milk every day? YES:  Lbs/Ozs  if yes: How many cups per day? Has your child always drank milk every day (after being weaned from breast or bottle)? yes no if no, at what age did she/he start drinking milk every day?  NO:  years old.  if no: Has your child ever drank one or more cups of milk per day (after being weaned from breast or bottle)? yes: at what age did she/he stop drinking milk every day? How many cups did he/she drink until that age? no:  2.3  Is your child on a special diet?  If yes:  (never drank milk on a daily basis after being weaned) Yes  vegetarian low sodium low cholesterol other  Please specify:  No  years old. cups per day  85 3.0  Medical History and Status:  3.1  Has your child ever been treated for any of the following conditions? Yes No food allergies  0  0  hypothyroidism  0  0  other allergies  0  0  hyperthyroidism  0  0  asthma  0  0  other conditions (please list)  3.2  Is your child currently taking any medications?  Yes  No  If yes, what medication(s) is your child taking?  What are these medication(s) for?  3.3  Has your family doctor ever said that your child has a heart condition and that he/she should only do physical activity recommended by a doctor? Yes No  3.4  Does your child complain of chest pain when they are doing physical activity? Yes  No  3.5  In the past month, has your child complained of chest pain when they were not doing any physical activity? Yes No  3.6  Does your child have a bone or joint problem that could be made worse by a change in their physical activity? Yes No  3.7  Does your child lose their balance because of dizziness or do they ever lose consciousness? Yes No  3.8  Do you know of any other reason why your child should not participate in physical activity? Yes  No  86  4.0  Bone History:  4.1  Has your child ever been hospitalized, confined to bed or had a limb immobilized (i.e., arm in a cast)? Yes No If yes: list condition, approximate date and time involved (Example: wrist fracture summer, 1990 Reason  4.2  indicate who was affected mother maternal grandmother maternal grandfather  Is there a history of osteoporosis in your family? If yes:  4.4  Date  Time Involved  Is there a history of wrist, hip, or spine fractures in your family? If yes:  4.3  10 weeks)  indicate who was affected mother maternal grandmother maternal grandfather  Yes  No  father paternal grandmother paternal grandfather Yes  No  father paternal grandmother paternal grandfather  Is there a history of any other bone disease in your family? Yes If yes:  No  please indicate the family member(s) affected  1. 2. What is the name of the condition(s) affecting this family member? 1. 2.  5.0  Physical Activity:  5.1  How would you rate the physical activity level of your child? Physical activity is defined as vigorous activity that makes them sweat and/or breathe hard. Inactive Sometimes active Moderately active Often active Very active THANK YOU FOR YOUR PARTICIPATION  87  Appendix C Sit-and-Reach T h e participant will begin by performing two 15 s e c o n d stretches per leg before proceeding to the sit a n d r e a c h m e a s u r e m e n t . T h e participant will r e m o v e their s h o e s a n d sit with their feet flat a g a i n s t the sit a n d r e a c h block. T h e i r feet will b e p l a c e d just wider than the width of the sliding m e c h a n i s m . T h e participant will p l a c e o n e hand on top of the other a n d situate their fingertips at the e d g e of the sliding m e c h a n i s m . A s they breathe out, the participant will r e a c h forward a s far a s p o s s i b l e k e e p i n g their l e g s straight. T h i s m e a s u r e m e n t will be repeated a n d the highest s c o r e (cm) will be recorded (137). Grip  Strength  T h e participant will s t a n d holding the d y n a m o m e t e r in their h a n d with the arm holding the d y n a m o m e t e r a b d u c t e d 4 5 ° from their body. W h i l e breathing normally, they will s q u e e z e the d y n a m o m e t e r a s hard a s p o s s i b l e . T w o m e a s u r e m e n t s will be taken for e a c h h a n d a n d the highest s c o r e o n either hand will b e r e c o r d e d (137). Push-ups T h e participant will lie in a prone position a n d p l a c e their h a n d s on the floor just wider than their s h o u l d e r s (finger tips pointing forward). Their feet will be p l a c e d together a n d their l e g s a n d b o d y will b e held in a straight line. T h e participant will b e g i n with their b o d y lifted off of the floor with only their h a n d s a n d t o e s in contact with the ground. U s i n g their t o e s a s a fulcrum the participant will b e n d their a r m s to lower their body towards the floor. T h e y will lower their b o d y until their a r m s r e a c h a 90° angle at the e l b o w joint after w h i c h , they will straighten their a r m s to return to the starting position. T h e participant will c o m p l e t e a s m a n y c o n s e c u t i v e p u s h - u p s a s p o s s i b l e in a rhythmical f a s h i o n . T h e p u s h - u p a s s e s s m e n t will be terminated for the following r e a s o n s : volitional fatigue, incorrect technique for more than two c o n s e c u t i v e p u s h - u p s , inability to maintain a rhythmical p a c e (137). Curl-ups T h e participant will lie s u p i n e with their a r m s at their s i d e s , k n e e s bent to 90°, feet together a n d flat on the floor. T h e y will curl their b o d y u p w a r d s while sliding their fingers along the g r o u n d t o w a r d s their feet. T h e participant will curl-up until their fingers h a v e travelled 1 0 c m from their starting position. C u r l - u p s will be performed keeping p a c e with the rhythm of a m e t r o n o m e . T h e m e t r o n o m e p a c e will be set at 4 0 b p m . T h e participants will perform a s m a n y curl-ups a s p o s s i b l e . T h e curl-up a s s e s s m e n t will b e terminated for the following r e a s o n s : volitional fatigue or inability to curl-up the required 10 c m (137).  88  Appendix D  Table D.1 Average 'on' and 'off times for each morning and evening during the measurement of habitual physical activity. Day of the  Morning  Standard  Week  (on time)  Deviation  Wednesday  N/A  N/A  Range  N/A  Evening  Standard  (off time)  Deviation  21:44:00  0:58:00  Range  20:45:4522:42:00  Thursday  7:38:00  0:44:55  6:53:15-  21:20:00  1:11:00  8:23:00 Friday  8:06:00  1:06:27  6:59:30-  22:31:00 21:58:30  1:26:45  9:12:30 Saturday  9:04:30  1:25:45  7:38:45-  9:15:07  1:24:36  7:50:3010:39:45  20:31:0023:39:00  22:01:15  1:37:45  10:30:15 Sunday  20:09:00-  20:23:3023:39:00  21:14:44  1:15:15  19:59:3022:30:00  90  Appendix F  Acfi<!n-Schools/Be ACTION SCHOOLS! BC 5-DAY ACTIVITY LOG - Spring 2006 Name: Grade:  School: Division:  Directions: 1)  Please have your child wear the motion sensor under their clothing.  2) The motion sensor should be fitted snugly on the waist with the sensor positioned in the front above the hip. The belt should feel comfortable but not floppy. 3) The motion sensor should be worn for 12 hours (8 AM - 8 PM) and should only be removed during that period if the child is going swimming, having a bath or a shower. It is not waterproof. 4)  Please note the time when the motion sensor is first put on the child and when it is taken off daily on the log on the reverse side of this form as well as anything that affected your child's movement patterns on any given day.  5) The motion sensor is like a smart 'pedometer' but it is very valuable. Please have your child put on the motion sensor on Monday morning to take it into school and an AS! BC researcher will collect them from the classroom. Thank you very much for you help!  91  Monitor:  Wednesday  Thursday  Friday  Saturday  Sunday  No  No  No  No  No  Yes  Yes  Yes  Yes  Yes  No  No  No  No  No  Yes  Yes  Yes  Yes  Yes  No  No  No  No  No  Yes  Yes  Yes  Yes  Yes  Dates  On Time AM Off Time PM Did weather change your routine?  Did illness change your routine?  Was motion sensor removed during wear time?  : If yes, what time? Why was the monitor removed?  Any problems? Please explain.  to  :  to  :  to  :  to  :  to  92 Appendix G  Table E.1 Description of health-related physical fitness and physical activity data in Caucasian and Asian girls. BMI=body mass index, MVPA=moderate-to-vigorous physical activity. Variable  N  Caucasian Girls  N  Asian Girls  Age (years)  38  10.0 ± 0 . 6  53  10.0 ± 0 . 6  Height (cm)  38  1.41.5± 7.6  53  140.9 ± 7 . 5  Weight (kg)  38  35.4 ± 6.4  53  35.2 ± 8.6  BMI (kg/mO  38  17.6 ± 2 . 0  53  17.5 ± 3 . 0  Waist Circumference (cm)  38  62.6 ± 5.7  53  62.9 ± 7.9  Systolic Blood Pressure (mmHg)  38  96.7 ± 9.3  53  97.0 ± 9 . 0  Diastolic Blood Pressure (mmHg)  38  62.0 ± 9.7  53  62.0 ± 8.4  Pulse Rate (bpm)  36  86.8 ± 14.0  53  88.4 ± 11.8  Total Laps Run  38  26.0 ± 13.0  53  18.0 ± 10.0  Sit-and-Reach (cm)  38  26.0 ± 10.0  53  29.0 ± 7 . 0  Curl-ups  38  14.0 ± 18.0  53  9.0 ± 9 . 0  Push-ups  38  6.0 ± 9 . 0  53  2.0 ± 5 . 0  Grip Strength (kg)  38  33.0 ± 8.0  53  32.0 ± 7 . 0  Musculoskeletal Fitness Score  38  0.3852 ±2.3157  53  -0.2762 ± 1.0910  Average Counts Per Minute  38  499.1 ± 158.3  53  380.1 ± 102.0  Average M V P A Per Day  38  127.0 ± 4 0 . 8  53  103.9 ± 2 8 . 6  93  T a b l e E.2 D e s c r i p t i o n of health-related p h y s i c a l fitness a n d p h y s i c a l activity d a t a in Asian and C a u c a s i a n boys. B M I = b o d y m a s s index, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity.  Variable  N  Caucasian Boys  N  Asian Boys  Age (years)  35  10.0 ± 0 . 6  44  10.0 ± 0 . 6  Height (cm)  35  142.4 ± 6 . 5  44  140.4 ± 8 . 3  Weight (kg)  35  36.2 ± 7.4  44  36.9 ± 8 . 5  BMI (kg/m )  35  17.7 ± 2 . 3  44  18.6 ± 3 . 0  Waist Circumference (cm)  35  63.4 ± 6.6  44  65.7 ± 8.0  Systolic Blood Pressure (mmHg)  34  97.3 ± 7 . 0  43  98.9 ± 7.0  Diastolic Blood Pressure (mmHg)  34  62.1 ± 6 . 0  43  63.9 ± 7.9  Pulse Rate (bpm)  33  85.3 ± 10.5  43  88.7 ± 11.1  Total Laps Run  35  31.0 ± 15.0  44  2 1 . 0 ± 12.0  Sit-and-Reach (cm)  35  24.0 ± 6 . 0  44  25.0 ± 7 . 0  Curl-ups  35  21.0 ± 2 2 . 0  44  8.0 ± 7 . 0  Push-ups  35  7.0 ± 8 . 0  44  4.0 ± 5 . 0  Grip Strength (kg)  35  36.0 ± 6.0  44  34.0 ± 7.0  Musculoskeletal Fitness Score  35  0.5858 ± 1.6407  44  -0.4660 ± 1.1581  Average Counts Per Minute  35  540.2 ± 120.6  44  474.5 ± 117.8  Average M V P A Per Day  35  140.1 ± 3 2 . 5  44  129.0 ± 3 4 . 6  z  94 Appendix H T a b l e E . 3 D e s c r i p t i o n of health-related p h y s i c a l fitness d a t a in children without p h y s i c a l activity d a t a . B M I = b o d y m a s s index. Variable  N  Boys  N  Girls  Age (years)  52  10.0 ± 0 . 5  46  9.8 ± 0 . 8  Height (cm)  50  141.4 ± 6 . 9  47  141.0 ± 7 . 3  Weight (kg)  50  37.3 ± 9.7  46  35.6 ± 6 . 8  BMI (kg/m')  50  18.5 ± 3 . 4  46  17.8 ± 2 . 8  Waist Circumference (cm)  50  65.6 ± 9.4  47  62.2 ± 6.6  Systolic Blood Pressure (mmHg)  47  96.5 ± 9 . 5  41  96.2 ± 10.8  Diastolic Blood Pressure (mmHg)  47  63.3 ± 8 . 6  41  63.5 ± 11.1  Pulse Rate (bpm)  46  89.9 ± 12.5  41  89.6 ± 12.8  Total Laps Run  48  26.6 ± 13.3  42  23.3 ± 12.1  Sit-and-Reach (cm)  49  24.0 ± 7 . 0  42  28.0 ± 7.0  Curl-ups  49  13.0 ± 15.0  42  11.0±8.0  Push-ups  49  7.0 ± 8 . 0  42  5.0 ± 5 . 0  Grip Strength (kg)  48  35.0 ± 7.0  42  32.0 ± 7.0  Musculoskeletal Fitness Score  48  0.1016 ± 1.6751  42  0.0729 ± 1.1230  95  Appendix I Capturing Physical Activity Tempo in Elementary School-Aged Children K. A s h l e e M c G u i r e , L i n d s a y A . Nettlefold , S h a n n o n S . D . B r e d i n , H e a t h e r A . M c K a y , Patti-Jean N a y l o r , D a r r e n D . E . W a r b u r t o n . U n i v e r s i t y of British C o l u m b i a , V a n c o u v e r , B C ; U n i v e r s i t y of Victoria, Victoria, B C 1  2  1  1  1  1  1  2  T h e t e m p o of children's activity h a s b e e n d o c u m e n t e d to b e s p o r a d i c a n d rapidly c h a n g i n g . T h e s e characteristics m a k e data acquisition in this a g e group challenging. A c c e l e r o m e t e r s are p o p u l a r in the a s s e s s m e n t of p h y s i c a l activity in youth h o w e v e r data is c o m m o n l y captured in 1 minute e p o c h s , c o n s e q u e n t l y m a s k i n g s p o r a d i c activity. Therefore, the p u r p o s e of this investigation w a s to d e t e r m i n e the t e m p o of children's physical activity using a 15 s e c o n d e p o c h with a specific e m p h a s i s o n the time spent in moderate-to-vigorous intensity p h y s i c a l activity ( M V P A ; £ 3 M E T s ) . T o a s s e s s habitual physical activity, children (8-11 yrs) wore a G T 1 M activity monitor at the hip during w a k i n g h o u r s o v e r a 5 d a y p e r i o d . A l l children w e r e part of a larger investigation (Action S c h o o l s ! B C ) . T o be included in the a n a l y s i s , children w e r e required to w e a r the monitor for at least 8 h o u r s per d a y o n at least 4 d a y s . O n e h u n d r e d fifty-seven children met the criteria. A g e - s p e c i f i c cut-points d e v e l o p e d by Trost a n d c o l l e a g u e s w e r e revised for u s e with 15 s e c o n d e p o c h s a n d d a t a w a s a n a l y z e d u s i n g c u s t o m i z e d software. O u r results indicate that children s p e n d 1 5 % of their monitored time in M V P A . Eighty-five percent of the total time s p e n t in M V P A w a s a c c u m u l a t e d in bouts of activity l e s s than 5 minutes in duration a n d o n a v e r a g e , t h e s e bouts lasted only 31 s e c o n d s . Eight percent of the activity bouts lasted b e t w e e n 5 a n d 10 minutes; 5 % in 10 to 2 0 minute bouts; a n d 2 % in bouts lasting greater than 2 0 minutes. O n l y 2 9 % of the children registered at least 1 bout lasting greater t h a n 2 0 minutes, while 6 8 % registered at least 1 bout of activity lasting 10 to 2 0 minutes a n d 9 7 % a c c u m u l a t e d activity in bouts of 5 to 10 minutes in duration. T h e results of this investigation s u g g e s t that a 15 s e c o n d e p o c h h a s sufficient resolution to detect the s p o r a d i c activity that is typical of children.  96 Appendix J  Physical Activity and Antecedents of Cardiovascular Disease in Children A . M c G u i r e , S . S . D . B r e d i n , H.A. M c K a y , P . J . N a y l o r , L.T.L. H o r i t a , Warburton . University of British C o l u m b i a , V a n c o u v e r , British C o l u m b i a University of V i c t o r i a , Victoria, British C o l u m b i a 1  1  1  1  2  1  D.E.R.  1  2  B a c k g r o u n d : R e d u c e d arterial c o m p l i a n c e is a n important predictor of c a r d i o v a s c u l a r d i s e a s e . It p r e c e d e s the d e v e l o p m e n t of traditional c a r d i o v a s c u l a r d i s e a s e risk factors. In adults, i n c r e a s e d p h y s i c a l activity is a s s o c i a t e d with i m p r o v e d arterial c o m p l i a n c e . H o w e v e r , it is u n k n o w n w h e t h e r regular daily p h y s i c a l activity in children exerts a similar positive influence o n arterial c o m p l i a n c e . P u r p o s e : T h e primary p u r p o s e of this investigation w a s to e x a m i n e the relationship b e t w e e n moderate-to-vigorous p h y s i c a l activity ( M V P A ) a n d arterial c o m p l i a n c e in children. M e t h o d s : T o a s s e s s habitual p h y s i c a l activity, children (n=115, 8-11 yrs) w o r e a G T 1 M Activity Monitor for 13 hrs (on average) daily o v e r a 5 d a y period. W e a l s o obtained concurrent m e a s u r e s of blood p r e s s u r e (mmHg), arterial c o m p l i a n c e (small a n d large artery, m l / m m H g ) a n d weight status (Body M a s s Index, k g / m ) . D a t a w e r e a n a l y z e d using P e a r s o n Partial C o r r e l a t i o n . 2  R e s u l t s : 1 6 . 5 % w e r e c l a s s i f i e d a s overweight a n d 5 . 2 % w e r e hypertensive. MVPA (counts per minute c o r r e s p o n d i n g to £3 M E T S ) a c c o u n t e d for approximately 6 % of the v a r i a n c e in s m a l l artery c o m p l i a n c e independent of B o d y M a s s Index, systolic blood pressure, a g e a n d g e n d e r . C o n c l u s i o n : T h e r e w a s a positive relationship b e t w e e n M V P A a n d v a s c u l a r health in this group of generally healthy children. T h i s e x t e n d s our previous findings by s h o w i n g that objectively m e a s u r e d p h y s i c a l activity is a l s o predictive of v a s c u l a r health. A n intervention d e s i g n e d to test the effect of M V P A on arterial c o m p l i a n c e w o u l d further delineate this relationship.  97 Appendix K  T a b l e K . 1 . T - t e s t s p e r f o r m e d b e t w e e n g e n d e r s . (*) d e n o t e s s i g n i f i c a n c e . M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity Variable  Boys (Mean)  Girls (Mean)  Significance Level  Musculoskeletal Fitness Score  0.1501  -.1303  p < 0.26  Total Laps  25.0  21.0  p < 0.06  Sit-and-Reach (cm)  25.0  28.0  p < 0.06  Grip Strength (kg)  35.0  32.0  p < 0.04  Height (cm)  141.3  141.2  p < 0.89  36.6  35.3  p < 0.25  Body M a s s Index (kg/m* )  18.2  17.6  p<0.12  Systolic Blood Pressure (mmHg)  98.0  97.0  p < 0.28  Diastolic Blood Pressure (mmHg)  63.0  62.0  p < 0.23  Heart Rate (bpm)  87.0  88.0  p < 0.86  Counts Per Minute  503.6*  429.8  p < 0.001  Minutes of M V P A Per Day  133.9*  113.5  p < 0.001  Minutes of M V P A Per Weekday  149.0*  124.6  p < 0.001  Minutes of M V P A Per Weekend Day  112.7*  98.4  p < 0.04  Minutes of Sporadic M V P A Per Day  104.7  98.0  p < 0.09  Minutes of Bouted M V P A Per Day  29.2*  15.5  p < 0.001  Weight (kg) 1  T a b l e K.2. A N O V A p e r f o r m e d b e t w e e n girls with a n d without valid p h y s i c a l activity data. Variable Girls Without PA Data Girls With PA Data Significance Level (Mean)  (Mean)  Age (years)  9.8  10.0  p<0.09  Height (cm)  141.0  141.2  p<0.71  Weight (kg)  35.6  35.2  p < 0.58  Total Laps  23.0  21.0  p < 0.68  Musculoskeletal Fitness  0.0729  -0.0336  p<0.16  Score  98 T a b l e K.3. A N O V A performed between boys with a n d without valid p h y s i c a l activity data. Variable  Boys Without PA Data  Boys With PA Data  (Mean)  (Mean)  Age (years)  10.0  10.0  p < 0.82  Height (cm)  141.4  141.3  p < 0.59  Weight (kg)  37.3  36.6  p < 0.42  Total Laps  27.0  25.0  p < 0.70  Musculoskeletal Fitness  0.1016  -0.0434  p < 0.43  Significance Level  Score  T a b l e K.4. A N O V A performed between s c h o o l s to determine intraclass correlation. M V P A = m o d e r a t e - t o - v i g o r o u s physical activity Variable  Between Schools  Within Schools  Variance  Variance  Counts Per Minute  1.073  13.901  14.974  0.07  Musculoskeletal  17.030  226.045  243.075  0.07  0.188  3.363  3.551  0.07  Total Laps  14.700  39.933  54.633  0.27  Minutes of M V P A  1.074  14.631  15.705  0.07  Total Variance  Intraclass Correlation  Fitness Score Body Mass Index (kg/m ) 2  Per Day  99  T a b l e K . 5 . A N C O V A u s e d to e x a m i n e differences b e t w e e n C a u c a s i a n a n d A s i a n boys. A g e , weight a n d height w e r e entered a s covariates. M V P A = m o d e r a t e - t o - v i g o r o u s physical activity Variable  Significance Level  Levene's Test (Significance)  Musculoskeletal Fitness Score  p < 0.007  p < 0.09  Total Laps  p < 0.03  p < 0.84  Curl-ups  p < 0.04  p < 0.001  Push-ups  p < 0.20  p < 0.62  Sit-and-Reach (cm)  p < 0.28  p < 0.66  Grip Strength (kg)  p<0.31  p<0.01  Systolic Blood Pressure (mmHg)  p < 0.36  p<0.19  Diastolic Blood Pressure (mmHg)  p < 0.69  p < 0.23  Heart Rate (bpm)  p<0.19  p < 0.92  Body Mass Index (kg/rr^)  p < 0.22  p < 0.08  Waist Circumference (cm)  p < 0.24  p < 0.09  Counts Per Minute  p < 0.03  p < 0.68  Minutes M V P A Per Day  p<0.12  p<0.41  T a b l e K . 6 . A N C O V A u s e d to e x a m i n e differences b e t w e e n C a u c a s i a n a n d A s i a n girls. A g e , weight a n d height w e r e entered a s covariates. M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity Variable  Significance Level  Levene's Test (Significance)  Musculoskeletal Fitness Score  p < 0.09  p<0.01  Total Laps  p<0.01  p < 0.06  Curl-ups  p < 0.32  p < 0.004  Push-ups  p < 0.009  p < 0.23  Sit-and-Reach (cm)  p < 0.78  p < 0.04  Grip Strength (kg)  p < 0.58  p < 0.26  Systolic Blood Pressure (mmHg)  p < 0.79  p < 0.95  Diastolic Blood Pressure (mmHg)  p < 0.97  p < 0.20  Heart Rate (bpm)  p < 0.59  p < 0.29  Body Mass Index (kg/m^)  p < 0.76  p < 0.004  Waist Circumference (cm)  p < 0.68  p<0.17  Counts Per Minute  p < 0.001  p < 0.001  Minutes M V P A Per Day  p < 0.001  p < 0.001  100 T a b l e K.7. P r i n c i p a l C o m p o n e n t A n a l y s i s in the w h o l e group. O n e c o m p o n e n t extracted from the m u s c u l o s k e l e t a l fitness c o m p o n e n t s . Component  Eigenvalue  Percentage Variance  1  1.560  38.994  T a b l e K . 8 . F a c t o r loadings b a s e d o n o n e c o m p o n e n t for the m u s c u l o s k e l e t a l fitness s c o r e in the w h o l e group. Factor  Factor Loading  Sit-and-Reach  0.380  Curl-ups  0.762  Push-ups  0.678  Grip Strength  0.612  T a b l e K . 9 . Principal C o m p o n e n t A n a l y s i s in girls only. O n e c o m p o n e n t extracted from the m u s c u l o s k e l e t a l fitness c o m p o n e n t s . Component  Eigenvalue  Percentage Variance  1  1.566  39.158  T a b l e K.10. F a c t o r l o a d i n g s b a s e d on o n e c o m p o n e n t for the m u s c u l o s k e l e t a l fitness s c o r e in girls. Factor  Factor Loading  Sit-and-Reach  0.495  Curl-ups  0.758  Push-ups  0.680  Grip Strength  0.534  T a b l e K . 1 1 . P r i n c i p a l C o m p o n e n t A n a l y s i s in b o y s only. O n e c o m p o n e n t extracted from the m u s c u l o s k e l e t a l fitness c o m p o n e n t s . Component  Eigenvalue  Percentage Variance  1  1.585  39.616  T a b l e K.12. F a c t o r l o a d i n g s b a s e d on o n e c o m p o n e n t in the m u s c u l o s k e l e t a l fitness s c o r e in b o y s . Factor  Factor Loading  Sit-and-Reach  0.435  Curl-ups  0.744  Push-ups  0.654  Grip Strength  0.643  T a b l e K.13. P r i n c i p a l C o m p o n e n t A n a l y s i s in the w h o l e group. O n e c o m p o n e n t extracted from the m u s c u l o s k e l e t a l a n d cardiorespiratory fitness c o m p o n e n t s . Component  Eigenvalue  Percentage Variance  1  2.098  41:952  T a b l e K.14. F a c t o r loadings b a s e d on o n e c o m p o n e n t in the m u s c u l o s k e l e t a l and cardiorespiratory fitness s c o r e in the w h o l e group. Factor  Factor Loading  Sit-and-Reach  0.351  Curl-ups  0.686  Push-ups  0.828  Grip Strength  0.467  Total Laps  0.774  102  T a b l e K.15. P r i n c i p a l C o m p o n e n t A n a l y s i s in the w h o l e group. T w o c o m p o n e n t s extracted from all health-related p h y s i c a l fitness c o m p o n e n t s . Component  Eigenvalue  Percentage Variance  1  2.479  35.416  2  1.817  25.959  T a b l e K.16. F a c t o r loadings b a s e d on two c o m p o n e n t s for the total health-related physical fitness s c o r e . Factor  Factor Loading  Factor Loading  (Component 1)  (Component 2)  Sit-and-Reach  0.356  0.118  Curl-ups  0.504  0.463  Push-ups  0.664  0.486  Grip Strength  -0.037  0.767  Total Laps  0.666  0.415  Body Mass Index  -0.770  0.533  Waist Circumference  -0.787  0.535  T a b l e K.17. F o r w a r d s t e p w i s e r e g r e s s i o n of cardiorespiratory fitness in girls. Fitness  Total Laps  Variables in  Standardized  Unstandardized  Model  Beta  Beta  M S K Score  .460  -.257  Adjusted R*  R* Change  .618  .184  .193  .139  .242  .066  (p< 0.001) Weight (p < 0.006)  103  T a b l e K.18. F o r w a r d s t e p w i s e r e g r e s s i o n of cardiorespiratory fitness in b o y s . C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity, MSK=musculoskeletal Fitness Total Laps  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  -.375  Adjusted R  R* Change  -.697  .400  .446  .210  .412  .400  .446  .083  .010  .400  .446  .148  .065  .400  .446  .528  5.284  .400  .446  -.049  -1.447  .400  .446  1  (p<0.01) Height (p<0.17) CPM (p < 0.70) M V P A Per Day (p < 0.49) M S K Score (p< 0.001) Ethnicity (p < 0.63)  T a b l e K.19. H i e r a r c h i c a l r e g r e s s i o n of health-related p h y s i c a l fitness c o m p o n e n t in boys. C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity, H R P F = h e a l t h - r e l a t e d p h y s i c a l fitness Fitness  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Total H R P F  Weight  -.579  Score  (p< 0.001) Height  Adjusted R*  R* Change  -.216  .157  .189  .439  .173  .157  .189  -.013  -.067  .157  .189  -.330  -1.967  .243  .093  -.191  -.005  .233  .000  .198  .017  .229  .006  (p < 0.01) Age (p<0.91) Ethnicity (p < 0.003) CPM (p < 0.46) M V P A Per Day (p < 0.45)  104 T a b l e K.20. Hierarchical r e g r e s s i o n of health-related p h y s i c a l fitness c o m p o n e n t in girls. C P M = c o u n t s per minute, M V P A = m o d e r a t e - t o - v i g o r o u s p h y s i c a l activity, H R P F = h e a l t h - r e l a t e d p h y s i c a l fitness Fitness Total H R P F Score  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  -.352  (p<  Adjusted R*  R' Change  -.143  .043  .075  .321  .133  .043  .075  -.108  -.557  .043  .075  -.202  -1.269  .111  .076  .122  .003  .130  .028  .067  .006  .120  .000  Adjusted R*  R' Change  0.001)  Height (p<0.01) Age (p<0.91) Ethnicity (p < 0.003) CPM (p < 0.46) M V P A Per Day (p < 0.45)  T a b l e K.21. Hierarchical r e g r e s s i o n of p u s h - u p s in b o y s . C P M = c o u n t s per minute. Fitness  Push-ups  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .461  .895  .147  .191  -.182  -1.395  .147  .191  -.010  -.066  .147  .191  .169  -1.269  .156  .020  .037  .003  .146  .001  (p < 0.008) Height (p < 0.32) Age (p < 0.94) Ethnicity (p<0.17) CPM (p < 0.75)  105  T a b l e K . 2 2 . Hierarchical r e g r e s s i o n of p u s h - u p s in girls. C P M = c o u n t s per minute. Fitness  Push-ups  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  -.098  -.192  .095  .136  .118  .901  .095  .136  .136  .901  .095  .136  .259  .212  .153  .064  -.122  -.162  .155  .012  Adjusted  R' Change  (p < 0.53) Height (p < 0.48) Age (p < 0.23) Ethnicity (p < 0.04) CPM (P < 0.27)  T a b l e K.23. Hierarchical r e g r e s s i o n of curl-ups in b o y s . C P M = c o u n t s per minute. Fitness Curl-ups  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .250  .410  .062  .110  -.159  -1.034  .062  .110  -.074  -.425  .062  .110  .222  .153  .086  .035  .042  .059  .075  .001  Adjusted R  z  R Change z  (p< 0.001) Height (p<0.01) Age (p<0.91) Ethnicity (p < 0.003) CPM (p < 0.46)  106 T a b l e K.24. Hierarchical r e g r e s s i o n of curl-ups in girls. C P M = c o u n t s per minute. Fitness  Curl-ups  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .128  .228  .053  .096  -.243  -1.691  .053  .096  .210  1.267  .053  .096  .039  .029  .049  .006  -.147  -.177  .055  .017  Adjusted R  2  R^ Change  (p< 0.001) Height (p<0.01) Age (p < 0.91) Ethnicity (p < 0.003) CPM (p < 0.46)  T a b l e K . 2 5 . Hierarchical r e g r e s s i o n of sit-and-reach in b o y s . C P M = c o u n t s per minute. Fitness Sit-and-Reach  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .108  .154  .120  .165  -.178  -1.007  .120  .165  -.261  -1.304  .120  .165  -.107  -.065  .111  .003  -.177  -.214  .126  .025  Adjusted R  z  R Change z  (p < 0.53) Height (p < 0.33) Age (p < 0.03) Ethnicity (p < 0.39) CPM (p<0.14)  107 T a b l e K.26. H i e r a r c h i c a l r e g r e s s i o n of s i t - a n d - r e a c h in girls. C P M = c o u n t s per minute. Fitness  Sit-and-Reach  V a r i a b l e s in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .154  A d j u s t e d R*  R' Change  -.259  .107  .148  -.016  -.107  .107  .148  -.116  -.665  .107  .148  .155  .110  .104  .007  .138  .159  .109  .015  A d j u s t e d R*  R* C h a n g e  (p < 0.34) Height (p < 0.92) Age (P < 0.32) Ethnicity (p < 0.23) CPM (p < 0.23)  T a b l e K . 2 7 . H i e r a r c h i c a l r e g r e s s i o n of grip strength in b o y s . C P M = c o u n t s per minute.  Fitness  Grip Strength  V a r i a b l e s in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .059  .060  .247  .286  .524  2.095  .247  .286  -.073  -.257  .247  .286  -.121  -.051  .242  .005  -.105  -.090  .243  .011  (p<0.71) Height (p < 0.003) Age (p < 0.52) Ethnicity (p < 0.30) CPM (p < 0.34)  108 T a b l e K.28. Hierarchical r e g r e s s i o n of grip strength in girls. C P M = c o u n t s per minute. Fitness Grip Strength  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Weight  .306  Adjusted R*  R' Change  .352  .397  .425  .416  1.877  .397  .425  -.055  -.215  .397  .425  -.010  -.005  .394  .004  .174  .136  .412  .023  (p < 0.02) Height (p < 0.003) Age (p < 0.56) Ethnicity (p < 0.92) CPM (p < 0.06)  T a b l e K.29. Hierarchical r e g r e s s i o n of systolic blood p r e s s u r e in b o y s . C P M = c o u n t s per minute. Fitness  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Systolic Blood  Weight  .458  Pressure  (p < 0.006) Height  Adjusted R*  R' Change  .154  .230  .270  .030  .040  .230  .270  .055  .066  .230  .270  .068  .010  .223  .004  .002  .001  .212  .000  (p < 0.86) Age (p < 0.64) Ethnicity (p < 0.57) CPM (p < 0.98)  109  T a b l e K.30. Hierarchical regression of systolic blood p r e s s u r e in girls. C P M = c o u n t s per minute. Fitness  Variables in  Standardized  Unstandardized  Model  Beta  Beta  Systolic Blood  Weight  .211  Pressure  (p < 0.20) Height  Adjusted R*  R' Change  .096  .036  .270  .104  .184  .036  .270  -.118  -.181  .036  .270  -.002  .000  .029  .004  -.196  -.061  .049  .000  (p < 0.56) Age (p < 0.33) Ethnicity (p < 0.99) CPM (p<0.10)  110 Appendix L Raw Data C2E2ID 1101 1168 1169 1207 1233 1283 1325 1349 1397 1457 1491 1508 1844 2080 2124 2147 2314 2345 2383 2432 2488 2521 2556 2650 2668 2693 2713 2887 2892 2921 3038 3161 3180 3284 3286 3292 3319 3349 3411 3423 3455 3558 3594 3627 3678 3693 3758 3767 3810  My ID T1 mpama4maf1 fqupa5bc1 fhusy4maf1 mpawi4maf1 fscha4wf1 fbaha5wf1 mkhsa5moc1 mdudo5moc1 fmoro5bc1 fdrma4maf1 ffial5bc1 mmijo4bc1 mfrju5wf1 mchma4nc1 marki4wf1 ferol4maf1 mmash4maf1 mdema4moc1 fdhsu5moc1 myada4maf1 mrami5bc1 mgrka5moc1 fmcsa5wf1 fgugo5moc1 falsa5bc1 fmoch5nc1 mromi5maf1 mgolu4maf1 fpjal5maf1 fmica5maf1 fnggl4moc1 fchgi5maf1 mfejo5wf1 mrojo4moc1 mgeda5maf1 mtajo4nc1 mslmi5maf1 mcabr4maf1 myoke5maf1 fdhpo5moc1 mjapr5moc1 fmiam4moc1 fsish4bc1 fchan4maf1 fchgr5maf1 fdhma4moc1 mvejo4wf1 fdhsh4moc1 fshlu5maf1  Gender M F F M F F M M F F M M M M M F M M F M M M F F F F M M F F F F M M M M M M M F M F F F F F M F F  sthtc 154.25 141.5 141.1 127.8 138.6 138.25 148.15 132.7 140.35 136.45 154.7 135.25 139.8 142.8 144.9 133.45 136.85 144.15 145.8 141.15 147.55 158.15 139.5 144.25 134.6 146.7 150.2 145.2 151.05 140.35 128.4 146.45 147.25 132.15 139.15 130.05 147.4 148.75 156.35 143.5 142.95 130.35 130.4 132.6 135.2 144.7 141.05 159.3 149.55  weightC 43.45 40.7 32.8 24.4 31.6 31.9 33.4 30.5 30.85 27.3 44.95 31.7 29.4 49.75 39.7 26.9 33 44.9 45.05 32.1 40.25 42.4 30 33 27 32.6 38.8 41.45 34.8 34.1 26.2 46.1 37.3 40.4 28.6 29.8 44.8 72.6 64.2 33.55 37.95 27.05 28.7 35.1 33.8 32.7 42.3 53 38.3  BMI 18.26163 20.32739 16.47479 14.93923 16.4498 16.69016 15.21749 17.3204 15.66139 14.66275 18.78231 17.32945 15.04295 24.39701 18.90835 15.10481 17.62075 21.60812 21.19238 16.11177 18.48789 16.95225 15.41604 15.85924 14.903 15.14807 17.19855 19.66035 15.25239 17.31129 15.89173 21.49424 17.20276 23.1338 14.77065 17.61958 20.61973 32.81124 26.26269 16.29254 18.57135 15.92008 16.87822 19.96274 18.49112 15.61747 21.26151 20.88547 17.12482  waistC 70.5 66.5 67.2 55.9 55.15 60.55 62.15 65.55 59.05 58.3 66.35 57.8 57.95 79.65 65.9 59.35 63.35 79.45 71.9 61 64.3 61.35 58 61.9 54.5 62.6 63.35 69.9 58.85 61.4 60.3 69.85 65 79.05 57.75 60.85 68.6 94.85 85.35 63.2 68 54.9 61.45 69.25 63.75 55.3 70.45 72.85 64.5  BPSY 105 99 111 92 99 82 90 96 107 91 101 98 99 104 92 109 98 107 99 100 102 90 92 91 92 99 102 94 103 106 92 108 99 92 99 102 89 119 107 86 102 99 84 93 83 94 102 93 110  BPDIA 64 61 68 61 58 55 51 66 72 52 69 66 56 65 66 61 66 75 53 61 69 69 48 59 56 60 61 59 68 72 57 76 55 57 73 73 68 . 79 61 54 64 50 44 61 67 60 66 60 78  Ill R a w Data 3811 3820 3826 3853 3941 3974 4023 4106 4221 4229 4303 4319 4338 4427 4470 4675 4678 4866 4896 4922 5014 5053 5116 5119 5125 5208 5216 5302 5313 5323 5380 5430 5521 5544 5573 5583 5689 5733 5735 5800 5805 5831 5868 5945 5949 6027 6039 6081 6108 6195 6247  fjale5nc1 mmibr4bc1 fwaer5maf1 mhake5maf1 mdupa4moc1 frova4nc1 fswra5bd msaka5moc1 msudi4moc1 mpabr5maf1 fpeha5bd mkike5bc1 fmema4maf1 fjema5wf1 fkras5bc1 fatpr5moc1 fhilu5moc1 mleso5wf1 flaja4maf1 mluli5moc1 fdama5moc1 fgrti5wf1 fprga5maf1 fanel4wf1 fhoma5bc1 fdech5bc1 fgisa5bc1 mpoma5bc1 fsujo4maf1 fhona5maf1 mlipa4bc1 flija5moc1 marno5moc1 fcsju4wf1 mgral4wf1 fsuan4maf1 mgudo4wf1 malst5wf1 mzhaa5maf1 monal4moc1 mfljo5maf1 fxizh5maf1 mmran5maf1 mbada4nc1 mmacy5bc1 fraa!4bc1 mliju5bc1 mkaap5moc1 fpeje4bc1 fwaas4wf1 fphsa4maf1  F M F M M F F M M M F M F F F F F M F M F F F F F F F M F F M F M F M F M M M M M F M M M F M M F F F  148.5 134.85 128.25 140.55 137.4 136.7 164.2 143 133.05 143.8 149.45 130.25 150.95 135.15 138.05 154.5 149.1 149.25 138.55 151.65 150.5 144.6 138.05 138.05 147.75 145.7 150.45 140 149.35 133 126.15 145.6 152 142.75 142 126.85 134.6 146.65 143.3 139.15 143.55 146.5 147.25 144.65 137.35 138.35 130.05 141.75 141.25 126.85 132.6  46.55 28.75 23.2 31.9 26.7 24.9 48.6 31.1 31.85 32.95 40 30.3 37.3 37.6 30.6 38.9 43.8 35.2 35.7 54.7 47.75 38.4 27.9 36.75 40.8 39.4 44.9 30.1 42.3 26.1 25.2 29.45 39.8 34.9 36.35 27.2 37.2 36.5 41.7 33 37.7 32.3 41.5 47.65 36.7 34.9 26 47.4 33.6 29.5 31.8  21.10896 15.81015 14.105 16.14838 14.14288 13.32485 18.02561 15.20857 17.99201 15.93447 17.90887 17.86023 16.36977 20.58523 16.05642 16.29644 19.70239 15.80207 18.59753 23.78496 21.08145 18.36516 14.63967 19.28344 18.68982 18.55996 19.83636 15.35714 18.964 14.75493 15.83529 13.89193 17.22645 17.12668 18.02718 16.90394 20.53302 16.97183 20.3069 17.04306 18.29511 15.04968 19.1398 22.7733 19.45399 18.23338 15.37279 23.59023 16.84079 18.33332 18.0859  72.6 57.2 52.9 58.6 56.75 51.7 64.35 59.05 65.7 61.25 62.6 58.55 65.6 68.35 54.15 58.55 62.9 57.1 64.95 78.5 71.8 68 55.1 65.9 63.85 62.45 67.5 55.5 68.75 57.5 56.5 53.45 69.4 60.45 64 56.9 71.05 64.1 65.25 59.5 67.6 62.6 65.05 72.2 66.2 ' 62.05 51.7 76.2 64.85 59 63.35  102 92 93 87 89 85 104 92 96 108 104 91 92 90 91 99 97 94 95 116 109 91 95 112 93 99 99 101 109 100 93 95 94 103 84 93 100 99 107 96 96 93 102 110 89 77 98 102 93 91 113  71 64 73 63 51 66 60 56 64 61 74 56 46 61 56 52 68 59 55 67 87 68 58 76 51 68 63 66 68 60 60 61 52 71 51 53 67 58 65 60 57 54 64 71 55 47 70 84 57 68 74  112  Raw Data 6333 6367 6543 6565 6572 6655 6673 6721 6758 6760 6788 6834 6845 6998 7034 7058 7102 7225 7247 7376 7386 7533 7558 7658 7662 7664 7673 7717 7864 7932 7938 7977 8021 8035 8073 8313 8436 8480 8508 8538 8579 8591 8664 8703 8714 8728 8867 8910 8915 8943 8947  fkelo5wfl mlija5nc1 mmita4bc1 femmi4bc1 fsuan5maf1 mshra4moc1 fchje4bc1 fduar5nc1 fhoch5maf1 fgoch5bc1 myary4wf1 fhehe5bc1 mhyra5moc1 mwaba5maf1 fkwkr5bc1 msoje5maf1 mneia4maf1 mclad4bc1 merim4bc1 fchro5moc1 mchch4maf1 mmore4maf1 mlavi5maf1 mheth4wf1 mgrde5maf1 fmaha4bc1 mchth4maf1 fnoem5wf1 mkobr5maf1 flaja5maf1 fluda5moc1 mwoke4maf1 fkwwi4moc1 fstmi4maf1 fgrsu5moc1 fluca5maf1 mloet5wf1 fmobr4maf1 ftase4maf1 fleyo5maf1 fhech4maf1 fbash5nc1 marju4nc1 mbhka4moc1 floem5wf1 fraha5moc1 mzike5wf1 mhush5nc1 mchhu4maf1 fphda4nc1 fwosa5bc1  F M M F F M F F F F M F M M F M M M M F M M M M M F M F M F F M F F F F M F F F F F M M F F M M M F F  134.65 141.9 135.1 131.65 140.45 134.5 129.25 149.05 134.05 134.2 135.35 146.4 157 144.75 140.6 159.35 148.85 131.4 137.4 139.1 151.45 147.4 144.15 147.45 135.65 137.7 140.2 147.15 142.45 139.45 147.2 139.4 151.1 136.6 140.45 139.35 137.45 131.05 135.85 147.55 140.45 148.65 133.1 139.6 155.25 139.85 139.05 138.5 124.8 140.5 138.05  33.7 34.3 28.7 29.05 31.2 25.4 25.2 58 26.5 29.05 30.9 40.3 53.5 33.3 30.4 51 44 27.35 29.9 38 48.95 37.5 47 40.5 28.6 27.6 41.4 52.6 37.3 39.55 51.75 33.8 30.5 35.3 38.05 30.8 30.4 27 31.25 54.8 32.6 48.9 28.1 26.55 43.45 30.65 38.05 47.1 25.1 37.05 25.9  18.58734 17.0345 15.7243 16.76117 15.81653 14.04071 15.0848 26.10742 14.74729 16.13025 16.86716 18.80282 21.70473 15.89304 15.37811 20.08473 19.85889 15.84042 15.8379 19.63945 21.34097 17.25982 22.61875 18.62797 15.5427 14.55597 21.06223 24.29211 18.38163 20.33806 23.88332 17.39367 13.35891 18.91792 19.28906 15.86123 16.09104 15.72135 16.93288 25.1711 16.52624 22.12988 15.86172 13.62366 18.02713 15.67132 19.67944 24.55395 16.11553 18.76876 13.59023  65.25 63.3 57.6 57.55 64.1 52.1 51.9 82.95 56.25 62.1 56.4 69.05 74.1 58.05 57.85 72.5 75.9 58.35 59.4 68.8 75.9 62.7 74.55 65.95 59.2 57.25 71.1 83.6 67.25 72.25 84.85 62.1 60.55 66.9 64.05 60.05 59.05 55 58.95 76.95 58.65 76.2 61.7 54 63.95 54.7 64.95 81.45 55.85 63.55 52.95  87 98 87 87 111 97 116 84 107 94 103 86 107 103 85 110 99 84 91 94 108 96 96 94 103 80 102 107 108 105 107 103 94 112 99 86 88 80 88 109 86 103 88 102 116 94 101 107 95 95 90  51 57 57 64 71 58 97 66 68 69 69 56 54 57 56 60 58 54 60 56 62 56 65 63 63 52 59 53 81 73 69 75 53 65 67 60 53 60 52 57 67 61 73 62 77 58 75 66 60 59 61  113 Raw Data 8981 9000 9032 9038 9147 9170 9546 9584 9585 9605 9607 9676 9693 9710 9733 9808 9869 9916 1017 1176 1275 1464 1700 1864 2053 2066 2265 2273 2415 2649 2701 2709 2714 2879 2995 3050 3054 3437 3651 3682 3685 3692 3770 3856 3991 4011 4066 4233 4247 4381 4593  fdhpa5moc1 fbaly5maf1 fchch4maf1 mtrda5nc1 fyaka4maf1 mchda4maf1 fboda4wf1 fzava5maf1 mther5bc1 fmema5moc1 mmako4maf1 fjije4moc1 frojh4maf1 mvelo4wf1 mjuma5maf1 fsoan5maf1 mwomo4bc1 flash4moc1 mveda4maf1 mchjo4maf1 fhama4bbf1 mriia5bbf1 fbrma4wf1 filan5maf1 mpapa4mf1 finke5bbf1 ffrka4mf1 mzhje5maf1 mswan5mf1 fsaje4nc1 fwage5wf1 fcala5bf1 fhash4mf1 mwaco4bc1 melli4maf1 mhora5maf1 floca4bbf1 mchto5ma1 mroro4nc1 mkijo5maf1 mbaru4maf1 fhaki4bbf1 faral5wf1 mfavi5nc1 mdebh4moc1 manbr5nc1 fmcme5wf1 fzhli4maf1 mlaro5bf1 flesa5bf1 mahav4moc1  F F F M F M F F M F M F F F M F M F M M F M F F M F F M M F F F F M M M M M M M M F F M M M F F M F M  145.1 154.55 140.2 149.6 145.55 133.65 143.05 147.6 141.35 138.75 138.75 134.45 130.15 138.7 136.15 132.45 135.8 134.65 145.15 141.45 128.1 150 131.25 143.9 143.45 146 138.6 149.05 147.25 137.1 134.15 135.35 134.7 144.1 138.15 136.75 142.5 143.7 136.35 143.9 146.45 134.6 145.05 138.85 143.1 144.1 140.35 142.45 134.5 141.65 133.65  39.5 49.4 36.1 46.5 40 28.2 33.6 41.5 34.4 28.85 31.8 29.7 25.95 32.9 36.5 29.9 40.45 27 43 36 24.3 60.3 31.7 38.8 32.8 39.95 29.55 49.1 33.25 37.2 26.9 24.3 30.1 34.2 41.85 30.5 38.1 37.2 42.55 32.6 34.5 35.1 42.7 49.9 31.45 31.3 35.9 30.2 32.15 35.7 30.4  18.76127 20.68183 18.36586 20.77733 18.88146 15.78742 16.41964 19.04914 17.21737 14.9858 16.51814 16.4299 15.31966 17.10185 19.69054 17.04383 21.93406 14.89193 20.40959 17.99271 14.8084 26.8 18.40181 18.73743 15.93943 18.74179 15.38265 22.10129 15.3349 19.79101 14.94758 13.26447 16.58942 16.47017 21.92773 16.30967 18.7627 18.0148 22.88702 15.74331 16.08571 19.3739 20.29516 25.88265 15.35824 15.07358 18.22509 14.88271 17.772 17.79242 17.01906  55 91 72.5 57 102 66.4 68 110 63.1 75 107 70.7 60 95 66.75 53 86 59 59 100 60.75 56 95 66.7 70 104 62.95 55 84 52.25 60 109 60.25 59 93 55.9 61 107 57.95 66 105 58.65 72 95 68.05 64 99 66.2 71 95 72.3 67 94 50.85 80 105 69.75 #NULL! #NULL! 61.1 66 86 55.35 69 104 95.05 50 86 62.45 61 97 55.85 71 100 60.85 59 93 71.4 #NULL! #NULL! 58.95 70 113 75.35 61 100 60.05 65 96 70.05 56 99 56.25 68 89 57.05 68 102 59 50 84 62.5 #NULL! 74.95 #NULL! #NULL! 62.8 #NULL! 62 91 64.45 58 93 63.45 72 100 70.45 68 105 58.1 56 95 62.45 60 87 59.85 60 80 71.6 66 97 89.5 80 95 56.8 49 87 62.7 75 94 63.9 64 99 56.35 55 92 61.5 69 95 61.75 69 88 62.8  114 Raw Data 4625 4908 5011 5160 5180 5187 5264 5400 5609 5765 5932 5961 5996 6058 6060 6062 6109 6152 6177 6208 6251 6279 6301 6344 6529 6631 6723 6814 6936 7077 7175 7204 7264 7293 7465 7563 7577 7631 7880 7911 7941 8043 8171 8308 8409 8411 8466 8520 8524 8573 8583  mnipe4maf1 mstha5mf1 mdisu4moc1 mlira5maf1 mlhlo4wf1 fsije4maf1 myeto5maf1 fjokrtlfl fhuda4bbf1 mzhal5maf1 fbash4bc1 morba4bf1 mshaa4bbf1 fbrsh5maf1 flesh5maf1 mmach4bbf1 fwija5moc1 fmcky5mf1 mhabo4maf1 fkran4wf1 fkoma5maf1 fnesh5mf1 fnosa4bc1 mmobr5maf1 mpajimafl mmemi5bbf1 mczig5mf1 fruvi4bc1 fgrme4bbf1 mquph5lf1 fdeta5maf1 mgash5lf1 fzhci4maf1 flodi5maf1 floma4bc1 fraem4maf1 mwede4bc1 fkyme4maf1 fviha5nc1 mstda4bbf1 mfast5nc1 mgabe4bbf1 mtuda4mf1 mbrma4bbf1 fchsy4moc1 fwaan5bbf1 fholi4bbf1 mvake4bc1 figan5maf1 frani5maf1 mmefe4mf1  M M M M F F M F F M F M M F F M F F M F F F F M M M M F F M F M M F M F M F F M M M M M F F F M F F  145.75 139.5 136.9 144.95 130.7 144.85 163.55 146.35 144.45 145.65 135.75 138.1 134.5 154.85 136.3 133.35 140.45 151.4 132.45 132.2 161.15 148.45 137.6 143.15 150.85 #NULL! 145.7 141.35 139.8 147.55 140.75 140.5 #NULL! 151.55 145.65 136.35 146.1 134.4 149.9 137.45 133.9 132.85 148.25 144.2 127.85 140.6 142.1 122.25 150.7 140.15 #NULL!  33.6 30.1 26.55 40.7 24.85 34 74.9 35.05 51.1 42.6 45.05 33.8 29.8 40.6 29.9 25.8 42 47.2 32.5 27.1 35.8 37.2 28.9 36.9 41.2 #NULL! 32.5 #NULL! 30.5 40 33.1 28.7 #NULL! 42.7 53.4 29.9 39.8 28.7 39.7 38.5 32.6 33.2 37.2 46.1 29.9 32.9 42 21.4 32.6 44.1 #NULL!  15.81693 15.46743 14.16634 19.37126 14.54706 16.20473 28.00146 16.36449 24.48983 20.08115 24.44641 17.72268 16.47296 16.93182 16.09457 14.50887 21.29148 20.59161 18.52591 15.50624 13.7855 16.88039 15.26374 18.0071 18.10534 #NULL! 15.30961 #NULL! 15.60578 18.37306 16.70826 14.53882 #NULL! 18.59157 25.17215 16.08277 18.64587 15.88852 17.66799 20.37845 18.18262 18.81113 16.92597 22.17024 18.29236 16.64276 20.79989 14.31911 14.3546 22.45186 #NULL!  64.45 57 53.6 67.2 56.35 56.75 90.45 61.85 80.85 68.55 80.1 60.8 60.55 61.95 55.6 54.95 64.05 72.15 65.95 56.75 62.25 63.4 56.6 64.45 62.5 #NULL! 57.1 65.95 55.8 65.45 60.05 56.45 #NULL! 61.9 80.55 54.6 63.9 56.45 60.7 73.9 63.8 59.45 62.05 79.85 58.9 61.7 68.85 48.8 55.8 68.55 #NULL!  96 93 86 101 91 97 122 85 103 98 105 70 93 #NULL! 103 105 #NULL! 106 80 97 135 104 98 90 97 106 101 84 92 93 93 #NULL! 102 101 93 #NULL! 92 #NULL! 110 96 96 91 98 109 101 85 73 #NULL! 88 109 97  63 55 59 62 61 54 84 59 67 60 63 46 59 #NULL! 67 51 #NULL! 64 52 59 120 54 58 75 63 73 68 48 58 56 61 #NULL! 72 63 54 #NULL! 56 #NULL! 65 60 59 61 61 73 65 54 57 #NULL! 57 70 63  115 Raw Data 8599 8629 8894 8926 8982 9099 9102 9139 9388 9433 9496 9553 9651 9669 9934 9996  fhije4wf1 fbrar5maf1 fcaar4maf1 mlaja4bbf1 mlowe4bf1 mzech5bbf1 ftoda5maf1 mstky5wf1 mbayo5lf1 mfoma4bbf1 frecl4maf1 fguca4maf1 fobfr4bbf1 fsaev4maf1 mulma5mf1 mguan4mf1  F F F M M M F M M M F F F F M M  143.45 152.55 136.6 136.95 133.45 143.25 147.25 139.45 136.45 132.3 134.75 136.45 148.65 135.8 139.45 154.6  31.3 51.4 42.4 34.7 28.7 41.3 43.3 29.9 30.3 27.9 30.05 38 41.6 31.4 41.3 59.3  15.21049 22.0871 22.72294 18.50143 16.11554 20.12615 19.96996 15.37567 16.27405 15.93986 16.54958 20.4097 18.82624 17.02669 21.23797 24.81051  55.7 73.1 73.4 58.85 61.35 68.6 64.5 58.05 59.85 62.85 57.6 63.05 61.45 58.65 73.6 78.1  96 99 #NULL! #NULL! 110 93 108 88 100 75 95 113 83 88 106 108  60 61 #NULL! #NULL! 67 55 71 64 75 59 59 82 60 64 67 66  116 Raw Data PR 98 87 99 84 103 74 90 104 99 83 84 86 86 93 92 #NULL! 91 86 94 93 89 94 63 85 76 103 83 67 91 106 112 82 73 85 95 94 79 84 86 97 85 80 67 86 77 116 96 92 84 101 98 97  SRMAX  Curlups 23 23 17 28 15 36 27 25 25 34 31 38 25 29 28 27 32 19 24 26 28 21 21 14 31 16 21 24 16 29 34 22 6 33 25 37 28 28 25 28 15 22 20 25 27 30 16 28 39 32 29 29  Pushups 37 4 9 9 23 16 8 22 12 23 28 8 20 0 32 7 9 8 0 14 27 0 8 0 5 11 8 21 0 2 0 15 15 4 11 9 14 0 7 4 22 3 16 0 0 20 10 18 9 5 94 0  3 5 14 3 2 8 0 2 2 21 2 3 28 0 10 5 6 15 1 12 2 0 7 0 10 0 1 10 0 0 0 8 0 0 6 10 0 0 0 0 2 0 5 3 1 0 4 0 13 0 14 0  GripTot 37 22 32 27 25 33 42 19 30 29 43 33 30 25 44 29 34 38 41 40 50 41 39 30 31 30 38 33 37 24 19 43 33 42 26 37 42 36 40 31 46 30 25 26 32 46 41 41 45 42 27 22  Lapsrun DOB Start Date Age 45 3/29/1996 12/7/2005 9.69 28 8/22/1995 11/16/2005 10.24 51 1/24/1996 11/30/2005 9.85 41 10/25/1996 12/7/2005 9.12 24 3/1/1996 11/2/2005 9.67 44 10/4/1995 11/2/2005 10.08 14 7/6/1995 2/1/2006 10.58 14 5/20/1995 2/1/2006 10.70 19 11/28/1995 11/16/2005 9.97 31 8/2/1996 11/30/2005 9.33 43 8/26/1995 11/16/2005 10.23 30 4/20/1996 11/16/2005 9.57 61 6/25/1995 11/2/2005 10.36 4 7/12/1996 1/11/2006 9.50 36 10/12/1996 11/2/2005 9.06 26 12/2/1996 12/7/2005 9.01 35 4/29/1996 11/30/2005 9.59 22 10/6/1996 2/1/2006 9.32 10 7/25/1995 2/1/2006 10.52 54 4/22/1996 12/7/2005 9.63 18 3/19/1995 11/16/2005 10.66 13 10/3/1995 2/8/2006 10.35 44 5/6/1995 11/2/2005 10.49 16 7/14/1995 2/8/2006 10.57 44 11/9/1995 11/16/2005 10.02 20 9/10/1995 1/11/2006 10.34 18 2/16/1995 11/30/2005 10.79 31 5/2/1996 12/7/2005 9.60 28 4/13/1995 11/30/2005 10.63 17 4/6/1995 12/7/2005 10.67 9 8/12/1996 2/1/2006 9.47 17 1/24/1995 11/30/2005 10.85 19 7/17/1995 11/2/2005 10.30 8 5/5/1996 2/1/2006 9.74 21 5/31/1995 12/7/2005 10.52 10 7/4/1996 1/11/2006 9.52 31 10/19/1995 12/7/2005 10.14 10 10/20/1995 12/7/2005 10.13 28 2/10/1995 11/30/2005 10.80 15 7/8/1995 2/1/2006 10.57 17 11/29/1995 2/8/2006 10.20 12 10/28/1996 2/8/2006 9.28 34 4/28/1996 11/16/2005 9.55 14 7/1/1996 12/7/2005 9.43 26 11/15/1995 12/7/2005 10.06 26 4/21/1996 2/8/2006 9.80 25 2/27/1996 11/2/2005 9.68 16 2/18/1996 2/1/2006 9.95 28 6/4/1995 11/30/2005 10.49 8 12/18/1995 1/11/2006 10.07 30 7/1/1996 11/16/2005 9.38 28 12/12/1995 11/30/2005 9.97  11 Raw Data 78 109 92 72 95 108 92 91 71 74 81 67 66 101 66 91 111 81 86 92 77 65 80 88 69 88 87 83 87 75 #NULL! 86 74 78 62 87 99 92 71 101 86 91 89 75 100 92 90 102 86 69 98 98 79  20 31 35 26 13 22 16 28 22 26 14 48 15 23 18 26 29 8 18 38 31 49 33 35 21 33 23 31 33 34 29 27 28 28 21 26 23 30 35 25 27 31 41 24 23 20 25 32 37 20 33 25 29  7 4 0 15 4 0 29 5 5 10 4 94 14 0 11 23 1 0 8 29 12 10 15 0 3 18 2 20 0 11 3 15 13 10 25 19 1 21 4 20 12 2 27 18 0 10 12 1 12 11 95 12 3  7 0 0 1 15 0 2 3 1 7 0 42 0 0 12 9 0 0 5 0 3 2 8 2 1 0 0 0 0 2 2 15 10 12 30 0 2 6 2 9 0 0 12 10 0 0 4 0 9 3 1 0 0  30 33 25 53 36 29 37 37 31 39 27 42 40 47 44 42 42 35 30 25 25 51 42 44 34 31 23 25 25 44 31 34 25 36 42 36 25 40 30 37 40 33 40 25 40 33 23 26 34 35 31 21 32  26 17 22 36 26 11 27 41 43 49 7 38 12 10 43 29 7 8 8 22 15 14 44 28 17 12 23 23 8 20 14 28 24 20 60 22 20 17 26 47 12 25 12 16 10 10 13 19 25 21 23 17 16  1/6/1995 10/18/1996 8/23/1996 9/19/1996 5/26/1995 1/11/1996 2/15/1995 1/22/1995 4/28/1995 2/18/1996 8/18/1995 8/4/1995 2/22/1995 7/17/1995 2/6/1995 11/10/1997 8/23/1995 2/6/1995 10/31/1995 11/19/1995 10/27/1996 9/29/1995 2/18/1995 4/25/1995 7/18/1995 1/23/1996 9/15/1995 11/21/1996 9/18/1995 1/4/1995 8/29/1996 5/26/1996 12/28/1996 6/21/1996 4/20/1995 7/30/1995 4/6/1996 2/13/1995 3/6/1995 11/28/1995 6/25/1996 12/28/1995 4/9/1996 4/28/1995 1/25/1995 5/31/1996 5/19/1996 10/11/1996 9/14/1995 1/17/1995 7/1/1996 1/30/1996 4/23/1995  11/30/2005 2/8/2006 1/11/2006 11/16/2005 2/8/2006 2/1/2006 12/7/2005 11/16/2005 11/16/2005 11/30/2005 11/2/2005 11/16/2005 2/8/2006 2/8/2006 11/2/2005 12/7/2005 2/1/2006 2/8/2006 11/2/2005 11/30/2005 11/2/2005 11/16/2005 11/16/2005 11/16/2005 11/16/2005 12/7/2005 11/30/2005 11/16/2005 2/8/2006 2/8/2006 11/2/2005 11/2/2005 11/30/2005 11/2/2005 11/2/2005 12/7/2005 2/8/2006 11/30/2005 12/7/2005 11/30/2005 1/11/2006 11/16/2005 11/16/2005 11/16/2005 2/1/2006 11/16/2005 11/2/2005 12/7/2005 11/2/2005 1/11/2006 11/16/2005 11/16/2005 12/7/2005  10.90 9.31 9.39 9.16 10.71 10.06 10.81 10.82 10.55 9.78 10.21 10.29 10.96 10.57 10.74 8.07 10.44 11.01 10.01 10.03 9.02 10.13 10.74 10.56 10.33 9.87 10.21 8.99 10.39 11.10 9.18 9.44 8.92 9.37 10.54 10.36 9.84 10.80 10.76 10.01 9.55 9.89 9.60 10.55 11.02 9.46 9.46 9.16 10.14 10.98 9.38 9.80 10.63  118 Raw Data 86 93 72 94 128 97 69 78 86 70 95 82 94 96 80 88 69 89 98 78 82 72 98 89 93 70 94 89 90 82 90 80 93 103 79 93 94 87 112 114 119 97 85 91 91 84 73 90 92 80 92 79 80  21 34 18 21 21 34 31 19 23 26 24 19 29 35 20 18 28 25 16 24 30 18 5 35 31 29 19 22 27 30 37 11 38 23 36 23 31 21 23 16 16 23 16 27 36 40 30 31 26 21 27 33 18  8 7 0 0 0 20 14 0 51 9 20 0 4 0 5 0 17 8 17 7 2 6 0 17 10 20 0 18 6 32 3 3 4 19 9 11 0 0 7 25 0 36 2 0 2 7 9 5 11 12 12 12 19  1 1 0 10 0 12 0 0 20 0 0 4 0 9 0 0 16 9 2 16 0 0 0 0 1 0 0 0 8 2 1 0 6 5 2 6 0 2 4 5 0 3 0 11 0 0 0 2 4 0 1 14 8  36 26 31 25 17 28 37 39 44 21 25 40 31 32 32 28 48 42 34 35 21 41 27 36 29 48 39 23 35 39 27 26 35 32 32 40 30 25 27 38 26 39 24 21 37 30 37 41 35 39 37 33 31  13 11 8 17 12 35 11 22 63 8 21 26 21 26 11 12 81 13 11 40 17 12 5 19 28 12 12 26 36 14 14 16 33 24 19 33 10 22 26 20 8 38 6 48 16 15 12 20 26 10 15 32 40  1/5/1996 11/18/1996 10/26/1995 9/15/1995 1/5/1995 9/13/1996 8/25/1995 12/1/1995 10/21/1995 8/28/1995 3/25/1995 5/17/1996 10/14/1996 2/3/1996 7/16/1995 1/7/1996 4/17/1996 11/17/1995 5/26/1996 8/8/1995 8/5/1996 11/25/1996 11/11/1995 12/5/1995 12/22/1995 4/19/1995 11/6/1996 4/12/1996 6/26/1996 3/5/1995 9/23/1995 7/21/1995 9/9/1996 3/2/1996 11/23/1995 2/8/1996 8/10/1995 6/21/1996 8/30/1996 1/24/1995 1/8/1995 4/29/1995 10/29/1995 7/9/1996 10/10/1996 3/16/1995 3/5/1995 3/8/1995 8/11/1996 1/19/1995 4/5/1996 8/22/1996 2/7/1995  2/1/2006 11/16/2005 1/11/2006 11/30/2005 11/16/2005 11/2/2005 11/16/2005 2/8/2006 12/7/2005 11/16/2005 11/30/2005 12/7/2005 11/16/2005 11/16/2005 2/8/2006 12/7/2005 12/7/2005 11/30/2005 11/2/2005 12/7/2005 11/16/2005 12/7/2005 11/2/2005 12/7/2005 12/7/2005 2/1/2006 12/7/2005 2/8/2006 12/7/2005 2/1/2006 11/30/2005 11/2/2005 11/30/2005 11/30/2005 12/7/2005 11/30/2005 1/11/2006 1/11/2006 2/8/2006 11/2/2005 2/8/2006 11/2/2005 1/11/2006 11/30/2005 1/11/2006 11/16/2005 2/8/2006 11/30/2005 11/30/2005 1/11/2006 12/7/2005 12/7/2005 11/2/2005  10.08 8.99 10.21 10.21 10.86 9.14 10.23 10.19 10.13 10.22 10.69 9.56 9.09 9.79 10.57 9.92 9.64 10.04 9.44 10.33 9.28 9.03 9.98 10.01 9.96 10.79 9.08 9.83 9.45 10.91 10.19 10.29 9.22 9.75 10.04 9.81 10.42 9.56 9.44 10.77 11.09 10.51 10.20 9.39 9.25 10.67 10.93 10.73 9.30 10.98 9.67 9.29 10.74  119 Raw Data 81 29 75 10 47 27 6/1/1995 78 23 5 0 30 15 12/6/1995 92 39 9 16 28 12 7/5/1995 #NULL! 23 11 13 40 14 7/18/1996 109 37 30 0 25 8 11/17/1996 79 29 26 19 30 53 7/3/1996 74 27 25 37 41 46 11/21/1995 67 41 11 14 36 42 4/14/1995 83 42 18 0 29 17 8/16/1995 88 20 0 0 20 11 9/2/1996 92 32 0 0 25 16 3/22/1996 88 25 19 0 38 21 1/16/1996 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 6/17/1996 79 22 0 2 23 20 11/9/1996 93 12 0 10 45 21 12/9/1995 66 30 21 14 23 19 3/1/1996 94 31 18 4 32 17 105 29 20 18 30 28 9/24/1996 17 79 0 34 13 44 1/22/1995 #NULL! 17 5 4 27 45 92 25 17 0 32 24 1/3/1995 79 19 13 14 40 41 2/22/1995 95 28 0 0 26 7 3/22/1996 62 22 4 13 26 12 6/21/1995 84 29 28 5 23 12 10/25/1995 85 21 11 8 22 12 11/7/1996 80 22 4 1 37 10 7/27/1996 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 8/6/1996 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 4/12/1995 83 20 34 0 0 29 11/5/1996 85 32 11 0 35 13 4/15/1995 89 25 0 2 36 9 2/16/1996 86 34 0 31 21 .7 8/8/1995 85 24 42 24 37 53 1/30/1996 99 19 1 0 35 18 4/24/1996 66 28 10 0 31 20 9/17/1995 104 21 1 2 30 10 8/28/1995 98 30 0 0 33 27 6/20/1996 22 108 15 5 34 18 5/19/1995 77 26 14 15 30 36 1/6/1995 96 41 11 1 33 22 3/27/1997 75 35 17 26 33 51 10/28/1995 84 37 13 14 35 38? 93 30 0 0 31 20 10/9/1996 84 11 23 3 31 18 6/26/1996 81 26 38 31 40 40 9/8/1995 97 27 15 0 22 13 5/9/1996 88 34 8 8 33 20 9/29/1995 94 33 10 6 34 34 10/30/1996 108 27 20 2 32 15 10/6/1996 #NULL! 20 0 0 #NULL! N U L L 6/4/1995 87 27 11 9 34 15 5/8/1996 109 25 4 0 40 11 8/19/1996  12/7/2005 10.52 11/16/2005 9.95 2/8/2006 10.60 9.37 11/30/2005 2/8/2006 9.23 12/7/2005 9.43 11/2/2005 9.95 12/7/2005 10.65 12/7/2005 10.31 11/16/2005 9.20 2/1/2006 9.86 9.87 11/30/2005 11/30/2005 9.45 1/20/2006 9.20 1/20/2006 10.12 11/2/2005 9.67 11/30/2005 ##### 11/23/2005 9.16 1/20/2006 11.00 11/23/2005 6.62 11/30/2005 10.91 11/23/2005 10.75 1/11/2006 9.81 11/2/2005 10.37 11/9/2005 10.04 9.04 11/23/2005 11/16/2005 9.31 11/30/2005 9.32 12/7/2005 10.66 1/20/2006 9.21 11/30/2005 10.63 1/11/2006 9.90 11/30/2005 10.31 9.85 12/7/2005 9.74 1/20/2006 11/2/2005 10.13 1/11/2006 10.37 2/1/2006 9.62 1/11/2006 10.65 11/2/2005 10.82 12/7/2005 8.70 11/9/2005 10.03 11/9/2005 10.72 2/1/2006 9.31 12/7/2005 9.45 11/23/2005 10.21 2/8/2006 9.75 11/30/2005 10.17 11/2/2005 9.01 12/7/2005 9.17 11/30/2005 10.49 11/9/2005 9.51 1/20/2006 9.42  120 Raw Data 75 26 16 0 36 16 12/13/1995 11/30/2005 9.97 83 32 0 0 24 16 6/3/1996 11/16/2005 9.45 96 31 10 9 40 32 2/16/1995 11/9/2005 10.73 80 17 7 4 35 33 5/30/1996 1/20/2006 9.64 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 5/4/1995 12/7/2005 10.60 84 38 12 3 24 26 8/4/1995 12/7/2005 10.34 103 33 17 12 34 34 7/13/1995 1/20/2006 10.52 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 9/8/1995 2/8/2006 10.42 94 17 22 17 39 20 4/21/1995 11/23/2005 10.59 84 29 1 2 17 19 11/15/1996 12/7/2005 9.06 110 21 4 2 26 34 5/30/1996 11/2/2005 9.43 79 31 17 10 41 22 11/17/1995 . 11/30/2005 10.06 78 9 23 10 35 20 2/27/1995 11/23/2005 10.74 76 36 2 0 24 11 12/11/1996 11/16/2005 8.93 92 32 7 6 43 30 1/31/1995 11/30/2005 10.83 88 33 10 4 47 37 4/20/1995 11/30/2005 10.61 91 23 23 14 55 43 3/16/1995 1/20/2006 10.85 110 20 13 17 37 50 5/9/1995 11/23/2005 10.54 79 31 0 0 27 7 3/3/1996 11/16/2005 9.71 101 36 22 42 0 56 3/14/1995 1/20/2006 10.86 81 26 20 8 37 25 4/8/1995 11/9/2005 10.59 107 25 16 12 35 35 ? 11/30/2005 10.92 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 6/11/1995 11/9/2005 10.41 86 41 21 1 31 31 3/29/1996 12/7/2005 9.69 91 29 9 4 40 40 5/4/1995 11/30/2005 10.58 60 17 3 0 41 13 6/17/1996 11/16/2005 9.42 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 12/20/1996 12/7/2005 8.96 115 12 42 1 40 24 5/10/1996 11/16/2005 9.52 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 8/27/1996 12/7/2005 9.28 79 24 13 8 41 15 9/14/1995 1/11/2006 10.33 90 22 10 37 5 16 4/15/1996 1/20/2006 9.77 83 13 6 0 26 10 8/28/1995 1/11/2006 10.37 91 25 0 20 39 33 7/2/1996 1/20/2006 9.55 102 21 83 25 42 47? 11/23/2005 ##### 71 16 0 0 43 20 5/30/1996 1/20/2006 9.64 115 23 11 0 23 11 4/11/1996 2/8/2006 9.83 81 35 6 12 31 38 10/5/1995 1/20/2006 10.29 91 30 4 0 46 31 7/24/1996 1/20/2006 9.49 #NULL! 13 0 7 22 5 7/24/1996 11/16/2005 9.31 83 34 25 4 31 18 1/26/1995 11/30/2005 10.84 107 44 2 4 32 20 11/2/1995 11/30/2005 10.08 127 35 3 7 29 21 3/28/1996 11/23/2005 9.66 89 26 19 8 28 14 7/25/1996 11/2/2005 9.27 102 36 4 1 37 24 6/17/1995 12/7/2005 10.48 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! 11/8/1996 12/7/2005 9.08 #NULL! 28 18 8 39 31 1/21/1996 1/20/2006 10.00 75 16 0 21 0 16 9/14/1996 11/9/2005 9.15 97 24 8 11 36 22 4/25/1995 1/20/2006 10.74 88 31 16 10 43 17 9/19/1995 11/30/2005 10.20 82 23 17 20 38 61 8/2/1995 11/2/2005 10.25 83 19 5 6 30 17 10/18/1995 11/9/2005 10.06 75 32 26 9 36 54 7/10/1996 1/20/2006 9.53 106 21 10 0 28 9 5/31/1996 11/30/2005 9.50  121 Raw Data 97 91 100 107 1 8  40 31 25 19 18  6 30 8 9 0  5 0 7 4 1  28 46 25 28 37  18 35 43 22 27  1/12/1996 1/26/1996 12/19/1996 6/19/1995 4/4/1995  11/30/2005 1/20/2006 12/7/2005 11/23/2005 11/23/2005  9.88 9.98 8.97 10.43 10.64  122 Raw Data  Teacher ID 235 740 653 235 856 521 220 220 650 653 740 350 546 146 856 748 653 330 730 435 650 730 521 730 650 140 152 235 886 426 126 168 521 330 426 146 426 435 152 220 710 960 350 235 435 960 856 126 658  School ID 13413 13441 13413 13413 13755 13755 13394 13394 13441 13413 13441 13441 13755 13392 13755 13413 13413 13394 13394 13413 13441 13394 13755 13394 13441 13392 13413 13413 13413 13413 13394 13413 13755 13394 13413 13392 13413 13413 13413 13394 13394 13394 13441 13413 13413 13394 13755 13394 13413  Ethnicity Code  Code Wear Days 1 1 2 2 1 1 2 2 1 1 1 2 1 2 1 1 2 2 2 2 1 2 1 2 1 1 1 1 1 1 2 2 1 2 1 2 1 0 1 2 2 2 1 2 2 2 1 2 2  Weather Code 2 1 2 0 0 0 0 0 0 2 0 0 0 2 1 0 2 0 0 0 2 2 0 2 0 0 2 0 2 0 0 2 0 0 0 0 0 2 2 0 0 2 2 2 0 0 2 0 2  Avg Wear Hours 0.2 0.4 0.8 0.2 1 1 0.8 0.8 0.4 0.8 0.4 0.4 0.8 0.8 1 0.2 0.8 0.8 0.2 0.8 0.4 0.8 1 0.2 0.4 0.8 0.8 0.2 0.8 0.2 0.6 0.8 1 0.8 0.2 0.8 0.2 0.2 0.8 0.8 0.2 0.2 0.4 0.2 0.2 0.2 1 0.8 0.8  13.03038162 14.20742638 12.615788 12.38531455 14.19519746 11.46798538 14.87826159 13.34169478 13.82560032 12.99116054 14.54383806 14.52882417 14.02849772 14.67736167 11.41135496 12.14050407 13.46826855 13.19309387 13.53792419 11.5962859 12.9605748 11.38985161 13.15086502 12.58724001 11.5798037 12.33339121 12.75257199 13.95453999 12.40630538 13.85650976 15.29065291 16.04234652 13.99456087 15.50810676 14.81843208 14.82103592 14.16380892 11.49250565 14.47436456 14.50402596 12.03054239 13.05224088 11.65384086 13.06194194 14.21710657 13.31597539 13.35473759 14.24185304 12.69418703  Total Counts 1844871 2061594 1401196 1418570 1809042 1144636 1414068 1560389 1809262 842437 2673140 1911797 1970807 2331735 1475926 1481188 1475721 1891861 1017709 1366065 1814363 1149876 1150977 749521 1882124 1756141 1511791 2102450 1323842 1117358 1303903 662495 3054020 1806882 1386605 1414668 1831794 1199520 1927022 1639927 1388741 1747523 1112212 1003620 1496331 1124231 1754449 1351248 1116219  123  Raw Data 140 350 886 886 960 451 740 710 450 426 740 740 653 521 740 710 710 521 748 220 710 147 658 621 650 740 740 740 435 658 350 710 710 856 856 653 621 521 435 730 168 435 168 451 740 350 740 220 130 147 748  13392 13441 13413 13413 13394 13392 13441 13394 13394 13413 13441 13441 13413 13755 13441 13394 13394 13755 13413 13394 13394 13755 13413 13755 13441 13441 13441 13441 13413 13413 13441 13394 13394 13755 13755 13413 13755 13755 13413 13394 13413 13413 13413 13392 13441 13441 13441 13394 13441 13755 13413  2 1 2 1 2 2 1 2 2 1 1 2 1 1 1 2 2 2 2 2 1 1 2 1 1 1 1 1 2 2 2 2 2 1 1 2 1 1 2 2 2 2 1 2 1 1 1 2 1 1 2  0 0 0 2 0 0 0 2 0 1 0 0 2 1 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 2 2 0 0 0 2 2 2 0 0 0 0 0 0 0 0 2 2 2 0 0 2  0.8 0.4 0.2 0.8 0.2 0.8 0.4 0.8 0.2 0.2 0.4 0.4 0.8 1 0.4 0.2 0.2 1 0.2 0.8 0.2 1 0.8 1 0.4 0.4 0.4 0.4 0.2 0.8 0.4 0.2 0.8 1 1 0.2 1 1 0.8 0.8 0.8 0.2 0.8 0.8 0.4 0.4 0.4 0.6 0.4 1 0.2  14.26282993 11.08035991 11.98981643 11.99502373 14.63494352 14.00944632 13.70176622 12.52115875 12.4347326 12.10382813 13.36931931 14.73149434 12.33420855 12.44261053 13.55507045 14.26568764 10.78489554 13.72558047 10.69961172 14.68529459 14.10089303 13.18547331 12.42113165 12.69394721 13.28454058 13.5788847 13.22929153 11.85187537 14.49245291 14.86404834 13.90958203 14.49772018 14.29998015 13.45981346 12.83602138 12.81245577 13.2431574 14.02849772 14.21520143 12.55010915 13.23881723 14.27902362 12.2113691 13.15388311 13.30454455 14.03607601 12.86064205 13.48854211 11.9352518 13.95324469 12.40154512  1811441 845824 724647 2041619 2473362 1170062 1292298 1349643 1562084 1277648 2215439 1408900 1202207 1409363 2778271 1042470 611894 1628605 1807906 1854896 1724921 3143363 1379103 1354067 2127978 2185348 1558457 1487769 948589 1063301 1907709 1681445 1772971 2251708 1342373 1324072 1164362 2476019 1847328 1816708 789370 1034613 2181715 2454646 2304014 2286340 1552021 1017313 1168040 1065839 1106598  124 Raw Data 546 657 350 350 435 126 350 140 168 740 147 650 710 426 650 658 163 350 350 710 748 163 886 147 426 350 435 546 435 426 390 235 960 163 220 152 521 653 886 426 653 140 451 960 546 710 147 140 653 146 740  13755 13392 13441 13441 13413 13394 13441 13392 13413 13441 13755 13441 13394 13413 13441 13413 13413 13441 13441 13394 13413 13413 13413 13755 13413 13441 13413 13755 13413 13413 13394 13413 13394 13413 13394 13413 13755 13413 13413 13413 13413 13392 13392 13394 13755 13394 13755 13392 13413 13392 13441  1 2 1 1 2 2 2 2 2 1 2 2 2 1 2 2 1 1 1 2 2 1 2 1 1 2 2 1 2 1 2 2 2 2 2 2 1 1 2 2 1 2 2 2 1 2 1 2 2 2 2  0 0 1 0 0 0 0 0 2 0 0 2 0 0 0 2 0 0 0 0 0 0 2 0 0 0 0 1 0 0 0 0 0 2 0 2 0 2 2 0 2 1 0 0 0 0 2 2 2 0 0  1 0.8 0.4 0.4 0.2 0.2 0.4 0.8 0.8 0.4 1 0.4 0.2 0.2 0.4 0.2 0.2 0.4 0.4 0.2 0.2 0.2 0.8 1 0.2 0.4 0.2 1 0.2 0.2 0.8 0.2 0.2 0.8 0.8 0.8 1 0.8 0.8 0.2 0.8 0.8 0.8 0.2 1 0.2 1 0.8 0.8 0.8 0.4  11.19611808 15.48108644 11.61153798 13.21500298 .13.88465965 14.05231197 14.05993253 14.57547512 14.59967963 14.32648164 15.14362405 12.85270745 14.43048224 14.12955854 13.58460012 12.39833792 11.27438371 14.32818579 14.31331613 13.09783687 13.43789353 13.66556857 14.08062001 15.08455076 13.54744989 13.88084937 13.04918898 12.49693173 14.24092082 13.01591586 14.69358211 13.18452074 14.55336376 14.86404834 12.77491566 13.5687453 11.18949843 12.271539 13.82628399 15.03562259 11.73403161 13.40339601 14.68481842 15.88206388 12.08049216 14.14566382 13.34465195 13.45259925 13.02157665 16.26608454 14.74442045  1791455 1986185 1363879 1812944 1457031 1174641 1566947 1478454 965758 671960 1580825 954170 2673618 2260111 977491 1133996 1382195 1418867 1748974 1006337 1071120 2167628 1748628 1656405 1836389 2069972 1229318 1269056 1443942 1312939 1004801 1706730 987357 1063301 1346007 1410105 1014057 2187334 1375395 1250647 1212354 1389736 2183768 2358029 1099830 1261715 1567407 1806361 1101429 1569522 2351298  125 Raw Data 730 658 886 657 235 748 621 426 650 710 886 960 163 147 426 435 350 330 886 653 574 145 621 168 810 145 210 658 750 451 521 530 810 350 653 426 574 658 451 168 163 574 546 140 126 140 546 748 530 131 126  13394 13413 13413 13392 13413 13413 13755 13413 13441 13394 13413 13394 13413 13755 13413 13413 13441 13394 , 13413 13413 13443 13443 13755 13413 13753 13443 13753 13413 13753 13392 13755 13411 13753 13441 13413 13413 13443 13413 13392 13413 13413 13443 13755 13392 13394 13392 13755 13413 13411 13411 13394  2 2 2 2 2 2 1 1 1 2 1 2 2 1 2 2 2 2 1 2 #NULL! #NULL! 1 #NULL! 2 1 1 2 1 #NULL! 1 1 #NULL! 1 2 2 1 2 2 2 #NULL! 1 1 2 2 1 1 2 2 #NULL! 2  0 2 2 0 0 0 2 0 0 0 2 0 0 0 0 0 1 0 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL!  0.2 0.8 0.8 0.8 0.2 0.2 1 0.2 0.4 0.2 0.8 0.2 0.2 1 0.2 0.2 0.4 0.8 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL!  13.21405041 13.74841316 12.168028 14.7638968 13.87227625 13.83417345 12.81388013 14.61692623 12.24044292 14.0978483 13.6625753 13.47029172 15.06502215 14.06194478 14.48222985 13.67890454 14.0699226 13.58174241 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL!  1304790 1046612 1120395 1215299 1684341 1496783 1557653 1334702 1372835 1192691 1277321 1454870 1464842 1501045 1141499 1108391 1858506 1669544 #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL! #NULL!  126 Raw Data 163 210 960 152 856 235 658 630 574 168 350 530 574 426 435 574 710 750 235 856 168 750 130 152 658 541 210 350 127 320 886 320 748 168 130 235 350 163 657 574 657 574 370 127 960 145 574 350 658 168 810  13413 13753 13394 13413 13755 13413 13413 13412 13443 13413 13441 13411 13443 13413 13413 13443 13394 13753 13413 13755 13413 13753 13441 13413 13413 13443 13753 13441 13443 13412 13413 13412 13413 13413 13441 13413 13441 13413 13392 13443 13392 13443 13753 13443 13394 13443 13443 13441 13413 13413 13753  1 1 2 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