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Quadriceps muscle activity in female runners with patellofemoral pain syndrome MacIntyre, Donna Lee 1986

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QUADRICEPS MUSCLE ACTIVITY IN FEMALE RUNNERS WITH PATELLOFEMORAL PAIN SYNDROME by  DONNA LEE MACINTYRE B.S.R., The University of B r i t i s h Columbia, 1980  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION in THE FACULTY OF GRADUATE STUDIES School of Physical Education and Recreation  He accept t h i s thesis as conforming to the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA J u l y 1986 ®  Donna Lee Maclntyre, 1986  In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  freely  a v a i l a b l e f o r r e f e r e n c e and study.  I further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s  thesis  f o r s c h o l a r l y purposes may be granted by t h e head o f my department o r by h i s o r her r e p r e s e n t a t i v e s . understood t h a t copying o r p u b l i c a t i o n o f t h i s for financial  gain  pHi^icAu  The U n i v e r s i t y o f B r i t i s h 1956 Main Mall Vancouver, Canada V6T 1Y3  Date  E-6  (3/81)  (Dot  thesis  s h a l l n o t be allowed without my  permission.  Department o f  It is  £DnCA)'0O Columbia  written  ABSTRACT  The a i m o f  this  s t u d y was t o d e t e r m i n e i f  t h e s u r f a c e EMG p a t t e r n s o f medial i s ,  the quadriceps muscles  v a s t u s l a t e r a l i s and r e c t u s  with patellofemoral activity  three of  of  extremity  t h e r e was a d i f f e r e n c e  femoris)  diagnosed  quadriceps  f e m a l e r u n n e r s f r e e o f knee p a i n and w i t h normal  lower  alignment.  L i n e a r e n v e l o p e EMGs f r o m v a s t u s m e d i a l i s , femoris,  (vastus  i n female runners  p a i n syndrome (PFPS) compared t o t h e  in  together with a footswitch  each s u b j e c t  r a n on a t r e a d m i l l  signal,  a t 12 k m / h .  vastus l a t e r a l i s  were d i g i t a l l y  and  recorded  rectus as  E a c h s t r i d e p e r i o d was  n o r m a l i z e d t o 100%, a n d t h e n t h e l i n e a r e n v e l o p e s  for  ten t r i a l s  from each  m u s c l e w e r e e n s e m b l e a v e r a g e d t o a c h i e v e a mean e n s e m b l e f o r e a c h  muscle  from each s u b j e c t .  muscle  for  all  of  Subsequently,  the subjects  i n e a c h g r o u p was  I t was a l s o t h e o b j e c t i v e o f difference  t h e g r a n d mean e n s e m b l e o f e a c h  i n t h e peak c o n c e n t r i c  this  computed.  study to determine i f  and e c c e n t r i c  and t h e h a m s t r i n g s between t h e e x p e r i m e n t a l The s u b j e c t s w e r e t e s t e d on an i s o k i n e t i c r a n g e o f 90°  a t an a n g u l a r v e l o c i t y o f  The r e s u l t s the groups patterns of  for  torques of  the  quadriceps  group and t h e c o n t r o l  group.  d y n a m o m e t e r (KINCOM) t h r o u g h a  200°/s.  showed no s t a t i s t i c a l l y s i g n i f i c a n t t h e peak EMG a m p l i t u d e s .  t h e r e was a  differences  between  I n f a c t when c o m p a r i n g t h e EMG  a c t i v i t y b e t w e e n t h e two g r o u p s ,  the grand ensemble average  of  in  the experimental group remained within + one standard deviation of the control group's mean EMG pattern.  However, when individual subjects with  PFPS were compared to the control group, there were periods 1n the gait cycle when the EMG amplitude was outside of + one standard deviation of the control group's mean. When comparing the two groups f o r the peak concentric and eccentric torques of each muscle group, again the results were not s t a t i s t i c a l l y significant.  The peak torques were also compared between groups as  hamstrings/quadriceps r a t i o s but found to be not s i g n i f i c a n t l y d i f f e r e n t . However, the mean concentric hamstrings/quadriceps r a t i o of the group with PFPS was found to be 1.02, which i s outside o f the range of values reported 1n the l i t e r a t u r e .  TABLE OF CONTENTS  Abstract  ii  List  of Tables  vi  List  of Figures  vii  Acknowl edgements  vi i i  Introduction  1  Purpose  3  Methodology  4  Subjects Experimental  4 Procedure  5  Testing of Muscle Strength  5  EMG M e a s u r e m e n t  7  Statistical  Analysis  8  Results  10  Discussion  21  G r o u p Mean M u s c l e A c t i v a t i o n P a t t e r n s  21  Peak C o n c e n t r i c  24  and E c c e n t r i c  Torque Values  Conclusions  31  Recommendations  33  V  References  Appendix 1  34  C h a r a c t e r i s t i c s of the Control and T h e i r  Appendix 2  Individual  Group  Subjects  Ensemble Averages  39  Individual  Peak T o r q u e V a l u e s and H a m s t r i n g s /  Quadriceps  Ratios  53  Appendix 3  Individual  Muscle A c t i v a t i o n Patterns  55  Appendix 4  Review o f  the L i t e r a t u r e  Patellofemoral  81  P a i n Syndrome  82  Introduction Anatomy o f  82  the Patellofemoral  Biomechanics of  the P a t e l l o f e m o r a l  Clinical  Features  Etiology  of Patellofemoral  82 Joint  85 86  Pain  90  Electromyography  95  Biomechanical  98  S t u d i e s of Running  I s o k i n e t i c Dynamometry Bibliography  Joint  101  vi  LIST OF TABLES  I.  Descriptive C h a r a c t e r i s t i c s of the Subjects  10  II.  Summary o f Manova  14  EMG P e a k A m p l i t u d e f o r V a s t u s M e d i a l i s , Vastus L a t e r a l i s  and Rectus  Femoris  III.  Summary o f T - T e s t  15  IV.  Mean P e a k T o r q u e V a l u e s a t 200°/s  16  for V.  the Right Quadriceps  and Hamstrings  Summary o f Manova  17  P e a k T o r q u e V a l u e s - G r o u p by M u s c l e by VI.  Contraction  Summary o f T - T e s t  18  P e a k T o r q u e - A n a l y s i s by R a t i o s VII.  D e v i a t i o n s o f t h e EMG A m p l i t u d e s C o m p a r e d t o t h e Control  G r o u p ' s Grand Ensemble  VIII.  Clinical  IX.  Individual  Peak T o r q u e V a l u e s  X.  Individual  Concentric  XI.  Clinical  Ratios  Group S u b j e c t s  Hamstrings/  54  f o r the R i g h t Leg  C h a r a c t e r i s t i c s and Dynamic S t r e n g t h o f  Syndrome  39  f o r t h e R i g h t Leg a t 200°/s..53  and E c c e n t r i c  Those S u b j e c t s With R i g h t Pain  Average  C h a r a c t e r i s t i c s of the Control  Quadriceps  20  Patellofemoral  55  vii  LIST OF FIGURES  1.  Grand Ensemble Averages o f  the Control  2.  Grand Ensemble Averages o f  the Experimental  Group  12  3.  Grand Ensemble Averages o f  the Experimental  Group  13  Compared t o t h e C o n t r o l  Group  11  Group  4.  S u b j e c t CR  41  5.  S u b j e c t CS  42  6.  S u b j e c t GG  43  7.  Subject JF  44  8.  S u b j e c t LS  45  9.  S u b j e c t MR  46  10.  S u b j e c t PB  47  11.  S u b j e c t PW  48  12.  S u b j e c t SL  49  13.  S u b j e c t SO  50  14.  S u b j e c t SP  51  15.  S u b j e c t VA  52  16.  S u b j e c t SC  58  17.  S u b j e c t HB  61  18.  S u b j e c t EC  64  19.  S u b j e c t TR  67  20.  S u b j e c t RW  69  21.  S u b j e c t SS  71  22.  S u b j e c t JH  75  23.  S u b j e c t JG  77  viii  ACKNOWLEDGEMENTS  I would l i k e f o r h i s guidance, t h e s i s work. Jean Wessel  t o e x p r e s s my a p p r e c i a t i o n t o D r . D. G o r d o n E . R o b e r t s o n patience  a n d e n c o u r a g e m e n t t h r o u g h o u t t h e c o u r s e o f my  I am a l s o g r a t e f u l  to Dr.'s  Don M c K e n z i e , J a c k  f o r t h e i r s u p p o r t and a s s i s t a n c e w i t h o u t w h i c h  have been a b l e t o c o m p l e t e t h i s and f r i e n d s who i n d i r e c t l y  study.  and o f t e n  Finally,  Taunton and  I would n o t  I w i s h t o t h a n k my f a m i l y  u n k n o w i n g l y h a v e p r o v i d e d me w i t h  u n d e r s t a n d i n g a n d t h e i n c e n t i v e t o c o m p l e t e w h a t s o m e t i m e s seemed l i k e a n impossible  task!  -  1 -  INTRODUCTION  The d r a m a t i c i n c r e a s e running,  i n the p o p u l a r i t y o f e x e r c i s e , and i n p a r t i c u l a r  i n t h e p a s t few decades h a s p r o d u c e d a need t o u n d e r s t a n d t h e  biomechanics o f r u n n i n g so t h a t e l i t e ances and c l i n i c i a n s  t h a t t h e r e may b e more v a r i a b i l i t y  mechanics o f running than i n w a l k i n g .  joint  forces  perform-  can t r e a t and perhaps p r e v e n t running i n j u r i e s .  need i s c o m p l i c a t e d by t h e f a c t  one o b v i o u s  a t h l e t e s can improve t h e i r  v a r i a b l e which a f f e c t s  This  in the  Mann ( 1 9 8 2 ) s u g g e s t s t h a t s p e e d i s  range o f m o t i o n , muscle a c t i v i t y and  i n the lower extremity.  However,  h e l d c o n s t a n t by a t r e a d m i l l , t h e n a f a c t o r  i f t h e r u n n i n g speed c a n be  such as p h a s i c muscle  activity  c a n be s t u d i e d a n d c o m p a r e d b e t w e e n g r o u p s o f s u b j e c t s . Our s o c i e t y ' s  increased particpation  r e s u l t e d i n an a s s o c i a t e d r i s e  i n physical  i n overuse i n j u r i e s .  a c t i v i t y has a l s o Malek  (1981) and Clement e t a l . (1981) have found from t h e i r records  t h a t t h e m o s t common s i t e  common c l i n i c a l  finding  Patellofemoral  of injury  i s patellofemoral  review o f c l i n i c a l  i s t h e knee and t h e most  p a i n syndrome  (PFPS).  p a i n syndrome h a s been d e s c r i b e d a s a d i f f u s e ,  l o c a t e d pain around t h e p a t e l l a which a r i s e s patella  and Mangine  (Grana e t a l . 1984).  Anatomical  i d e n t i f i e d a s h a v i n g some i n f l u e n c e  f a c t o r s w h i c h have  tracking of the been  on t h e a l i g n m e n t o f t h e p a t e l l a a r e  genu v a l g u m , genu r e c u r v a t u m , p a t e l l a a l t a , neck a n t e v e r s i o n , p r o n a t e d f e e t ,  from abnormal  poorly  a hypermobile p a t e l l a ,  inefficiency  femoral  o f t h e vastus medial i s  muscle and/or hypertrophy o f t h e vastus l a t e r a l i s  (Reynolds e t a l . 1983).  - 2 -  The e l e c t r o m y o g r a p h i c a c t i v i t y o f particular  the quadriceps  have been s t u d i e d i n  ( H a l l e n and L i n d a h l , 1967; L i e b m u s c l e work  (Pocock,  c o n c e n t r i c work weight-bearing  t h e m u s c l e s of t h e k n e e ,  and P e r r y ,  1971),  1963; E l o r a n t a and K o m i ,  (Komi,  1973),  isometric  contractions  i n a c t i v e and  1981),  a n d d u r i n g t h e l a s t 30°  (Reynolds et a l , 1983).  during actual  of extension  The n e x t l o g i c a l  Improvements i n e l e c t r i c a l  EMG s t u d i e s  advancements  t h e norm ( W i n t e r ,  1984).  of  muscle 1979;  press).  i n t h e p a s t few d e c a d e s  have  i n e l e c t r o m y o g r a p h i c a n a l y s i s of g a i t .  o f w a l k i n g , a b a s e l i n e of n o r m a l m o t o r p a t t e r n s  e s t a b l i s h e d and s p e c i f i c  possible  technology  in  has  Through  been  a b n o r m a l i t i e s c a n be d e t e c t e d when c o m p a r e d U t i l i z i n g t h e s e same t e c h n i q u e s ,  t o s t u d y t h e p a t t e r n s of m u s c l e a c t i v i t y  determine i f there are observable abnormalities  and  while  progession  r u n n i n g u s i n g EMG ( E l l i o t t a n d B l a n k s b y ,  Schwab e t a l . 1 9 8 3 ; M a c l n t y r e a n d R o b e r t s o n ,  made p o s s i b l e  resisted  during eccentric  m u s c l e a n a l y s i s p a r t i c u l a r t o r u n n i n g has been t o a n a l y z e t h e activity  in  it  is  i n r u n n i n g and  in certain  to  also to  clinical  conditions. Recent advancements i n muscle t e s t i n g t e c h n i q u e s , d e v e l o p m e n t of a n i s o k i n e t i c  the  dynamometer w h i c h c a n a s s e s s c o n c e n t r i c  e c c e n t r i c m u s c l e s t r e n g t h , h a v e made i t results with functional  in particular  activity.  p o s s i b l e to r e l a t e muscle  I t h a s b e e n shown by W i n t e r  and  strength  (1983)  that  o v e r one r u n n i n g s t r i d e t h e k n e e m u s c l e s a b s o r b a p p r o x i m a t e l y t h r e e a n d a half  t i m e s more e n e r g y t h a n t h e y g e n e r a t e , w i t h t h e l a r g e s t amount  eccentric of h i s  activity  findings  i n the quadriceps  during stance phase.  during running r e l a t e s  t o t h e u s e of t h e  The  of  importance  isokinetic  - 3 -  d y n a m o m e t e r a n d t h e n e e d t o be a b l e t o t e s t a n d t r a i n m u s c l e s concentric  and e c c e n t r i c  during  contractions.  Purpose The p u r p o s e o f  this  i n t h e EMG p a t t e r n s o f femoral  s t u d y was t o d e t e r m i n e i f the quadriceps  i n female runners w i t h  p a i n syndrome compared t o a group o f  p a i n and w i t h normal Secondarily,  this  lower extremity  t h e r e was a  female runners  the quadriceps  t o see i f  t h e r e was a s i g n i f i c a n t  patellofree of  knee  alignment.  s t u d y c o m p a r e d t h e peak c o n c e n t r i c  torque of  difference  and  eccentric  a n d h a m s t r i n g s a t an a n g u l a r v e l o c i t y o f 200°/s difference  s u b j e c t s w i t h and w i t h o u t p a t e l l o f e m o r a l  pain  between t h o s e groups syndrome.  of  - 4 -  METHODOLOGY  SUBJECTS  Twenty take part control  female r e c r e a t i o n a l in this  study.  runners,  aged 15-36 y e a r s ,  Twelve o f t h e s u b j e c t s were p l a c e d i n t h e  g r o u p a s t h e y h a d no c o m p l a i n t s o f k n e e p a i n , no p r e v i o u s  e x t r e m i t y s u r g e r y o r known m u s c u l o s k e l e t a l lower extremity alignment.  Clinic  and f o r e f o o t  (James,  alignment  abnormalities,  Normal  and f o r e f o o t less  1979), t h e degree o f p r o n a t i o n (Lehmkuhl  v a r u s 4° o r l e s s ,  r u n n i n g a t l e a s t 16 km/week The e x p e r i m e n t a l  (James e t  and S m i t h ,  no o v e r p r o n a t i o n , l e g l e n g t h  group c o n s i s t e d o f e i g h t  Sports Medicine C l i n i c .  rearfoot  discrepancy  These s u b j e c t s  were  (10 m i l e s / w e e k ) .  diagnosed as having patellofemoral  s u b j e c t s who h a d b e e n  p a i n s y n d r o m e b y t h e p h y s i c i a n s a t UBC  They c o m p l a i n e d o f r i g h t knee p a i n around t h e  and had t h e f o l l o w i n g  lower extremity malalignment  Q - a n g l e 15° o r m o r e , r e a r f o o t a n d f o r e f o o t  features:  a l i g n m e n t m e a s u r e s more t h a n 4°  a n d o v e r p r o n a t i o n o f t h e r i g h t f o o t when w e i g h t - b e a r i n g . their  rearfoot  v a l u e s w e r e c o n s i d e r e d t o b e : Q - a n g l e 15° o r l e s s ,  t h a n o n e c e n t i m e t e r a n d no genu r e c u r v a t u m .  patella,  and 'normal'  f o r Q-angle (Schamberger, 1983),  1 9 7 8 ) , l e g l e n g t h , and a l i g n m e n t a t t h e knee  1983).  lower  They were e v a l u a t e d by t h e p h y s i c i a n s a t  U.B.C. Sports Medicine  al.  volunteered t o  l e g l e n g t h and a l i g n m e n t a t t h e knee were a s s e s s e d .  were a l s o r u n n i n g p r i o r t o t h e o n s e t o f p a i n .  Furthermore These  subjects  - 5-  EXPERIMENTAL PROCEDURE  Testing o f Peak Torque The s u b j e c t s w e r e t e s t e d on a n i s o k i n e t i c  d y n a m o m e t e r (KINCOM) t o  d e t e r m i n e t h e peak t o r q u e o f t h e i r r i g h t q u a d r i c e p s four concentric  and e c c e n t r i c  and h a m s t r i n g s ,  during  contractions.  I l l u s t r a t i o n o f a subject being tested f o r quadriceps s t r e n g t h o n t h e KINCOM.  Each s u b j e c t was i n s t r u c t e d t o s i t w i t h h e r back a g a i n s t t h e back support of the c h a i r ,  t h e p e l v i s was s t a b i l i z e d by s t r a p p i n g , a n d t h e  p o s t e r i o r a s p e c t o f t h e k n e e was p o s i t i o n e d a t t h e f r o n t  of the chair.  - 6-  P o s i t i o n i n g of the subject's machine f o l l o w e d  l o w e r l e g a g a i n s t t h e f o r c e arm o f t h e  the d i r e c t i o n o f G o s l i n and C h a r t e r i s  (1979).  Subjects  were i n s t r u c t e d t o g r i p t h e s i d e s o f t h e s e a t f o r s u p p o r t d u r i n g t h e testing.  During hamstrings t e s t i n g additional  s t a b i l i z a t i o n was p r o v i d e d  by s t r a p p i n g t h e t h i g h t o t h e t a b l e . The s u b j e c t s w e r e g i v e n s t a n d a r d i z e d i n s t r u c t i o n s a n d t h e n submaximal t r i a l s were p e r f o r m e d b e f o r e  t h e maximal t e s t .  four  The range o f  m o t i o n f o r t h e k n e e movement was t h r o u g h a n a r c o f 90° (5° - 95°) a t a v e l o c i t y o f 200°/s, n o n - g r a v i t y c o r r e c t e d . concentric  c o n t r a c t i o n and an e c c e n t r i c  Each t e s t c o n s i s t e d o f a  contraction,  t o c o n c e n t r a t e on t w o c o n s e c u t i v e c o n t r a c t i o n s s u b j e c t performed f o u r maximal r e p e t i t i o n s (quadriceps  and h a m s t r i n g s ) w i t h v e r b a l  t h u s , t h e s u b j e c t had  f o r each r e p e t i t i o n .  f o r each muscle  Each  group  encouragement.  EMG Measurement The s u b j e c t s  r a n on a t r e a d m i l l , f i r s t  a t a s p e e d t h a t w a s 80% o f  their  normal  r u n n i n g pace and t h e n f o r a second t r i a l  until  10 s t r i d e s w e r e c o l l e c t e d b y t h e c o m p u t e r .  a t 12 km/h ( 7 . 5 MPH)  The f i r s t  trial  was u s e d  a s a warm-up f o r t h e s e c o n d r u n a t 12 k m / h . L i n e a r e n v e l o p e EMG s i g n a l s lateralis  and r e c t u s  digitally  r e c o r d e d a t 100 Hz e a c h .  the motor p o i n t s interelectrode  femoris,  from the r i g h t vastus medial i s , vastus  together with a footswitch  signal,  were  S u r f a c e e l e c t r o d e s were p l a c e d  o f each o f t h e muscles  (Delagi  s p a c i n g o f one c e n t i m e t e r .  over  e t a l . 1 9 7 5 ) , w i t h an  P r e p a r a t i o n o f t h e s k i n was  a c c o r d i n g t o t h e methods d e s c r i b e d by B a s m a j i a n  (1979).  - 7 -  I l l u s t r a t i o n of electrodes  in  The b i o a m p l i f i e r t h e g a i n was 1000, rejection  ratio  a s u b j e c t r u n n i n g on t h e t r e a d m i l l  the input  had a f r e q u e n c y  i m p e d a n c e was 10  (CMRR) was g r e a t e r t h a n 100 filter  (Winter,  trials  range of  20-1000  Hz,  megaohms a n d t h e common mode  dB.  personal  E a c h s t r i d e p e r i o d was n o r m a l i z e d t o 100% o v e r t h e 10  surface  place.  (custom-made)  second o r d e r band-pass  with  The a m p l i f i e r u t i l i z e d communication).  and then ensemble  f o r e a c h m u s c l e a n d f o r e a c h s u b j e c t by  averaged  computer.  a  - 8 -  Standard deviations  f o r each i n t e r v a l  were a l s o c a l c u l a t e d .  g r a n d ensemble a v e r a g e s f o r each m u s c l e and f o r a l l  of  Subsequently  the subjects  in  each group were computed.  S t a t i s t i c a l Analysis A multivariate analysis difference  (MANOVA) was done t o d e t e r m i n e i f  between groups f o r  (vastus medialis,  t h e peak EMG a m p l i t u d e f r o m e a c h  v a s t u s l a t e r a l i s and r e c t u s  femoris)  during  A s e c o n d MANOVA a n a l y s i s was p e r f o r m e d t o d e t e r m i n e i f difference  between groups f o r muscle s t r e n g t h  quadriceps  and h a m s t r i n g s , b o t h c o n c e n t r i c a l l y  An a n a l y s i s o f hamstrings,  the strength r e l a t i o n s h i p s  The l e v e l A visual  for  between  significance  stance.  in  the  eccentrically.  between t h e q u a d r i c e p s  and  to determine  group.  o f e a c h a n a l y s i s was s e t a t p < 0 . 0 5 .  o f more t h a n _+ one s t a n d a r d d e v i a t i o n  Furthermore, each i n d i v i d u a l ' s  s u p e r i m p o s e d on t h e c o n t r o l t h e r e were d i f f e r e n c e s  if  groups.  t h e m u s c l e a c t i v i t y when t h e e x p e r i m e n t a l  to the c o n t r o l  patterns.  muscle  a n a l y s i s o f t h e EMG d a t a was a l s o i n c l u d e d t o d e t e r m i n e  t h e r e was a d i f f e r e n c e patterns of  and  a  t h e r e was a  (peak t o r q u e s )  a s e x p r e s s e d a s a r a t i o , was done by a t - t e s t  t h e r e was a d i f f e r e n c e  t h e r e was  group's  in the  g r o u p was  if phasic  compared  EMG p r o f i l e  was  grand ensemble average t o determine  o f more t h a n + one s t a n d a r d d e v i a t i o n ,  if  i n t h e i r EMG  - 9 -  RESULTS  Table  I is  the subjects  a summary o f  i n each  t h e c h a r a c t e r i s t i c s and c l i n i c a l  findings  group.  TABLE I Descriptive C h a r a c t e r i s t i c s of  Control  AGE  (range)  Group  the  Subjects  Experimental  12  8  20 - 32 y e a r s  15 - 36 y e a r s  Group  HEIGHT  (range)  155 cm - 175 cm  1 5 2 . 5 cm - 1 6 7 . 5 cm  WEIGHT  (range)  53.2 - 63.6  50 k g - 6 3 . 6  KM/WEEK  (range)  19 -  56  KNEE P A I N  No  Q-ANGLE  15°  REARFOOT & FOREFOOT  4° o r  4  8 - 4 0 Yes  or  ALIGNMENT OVERPRONATION ( n )  kg  mild  less less  15°  o r more  4° o r more  kg  of  -  Figure activity  1 shows t h e g r a n d e n s e m b l e a v e r a g e s o f e a c h m u s c l e ' s EMG  (V.M. - vastus medial i s ,  lateralis)  10 -  f r o m t h e 12 s u b j e c t s  R.F.  - rectus  in the control  femoris, V.L. group.  the dotted l i n e s  standard deviation.  the g a i t c y c l e i s  s t r i k e to i p s i l a t e r a l the c y c l e .  heel  strike.  The g r a n d e n s e m b l e a v e r a g e s o f v a s t u s m e d i a l i s  grand ensemble average of  line  a r e + one from  heel-  T o e - o f f o c c u r r e d b e t w e e n 29 a n d 45% o f  The a m p l i t u d e o f t h e c u r v e s i s m e a s u r e d i n  r e p r e s e n t 11 EMG p r o f i l e s .  vastus  The s o l i d  r e p r e s e n t s the grand ensemble average w h i l e One h u n d r e d p e r c e n t o f  -  millivolts.  and r e c t u s  femoris  T h e r e w e r e t e n EMG r e c o r d i n g s o b t a i n e d f o r vastus  the  lateralis.  F i g u r e 2 r e p r e s e n t s the grand ensemble averages o f each muscle f o r eight 50% o f  subjects  i n the experimental  the g a i t  each f o r v a s t u s medial i s for  T o e - o f f o c c u r r e d b e t w e e n 30  rectus  group,  t h e r e were a t o t a l  of  and v a s t u s l a t e r a l i s , w h i l e  f e m o r i s was  e i g h t EMG  profiles  t h e number  of  seven.  F i g u r e 3 shows t h e g r a n d e n s e m b l e a v e r a g e o f e a c h m u s c l e f r o m experimental solid line lines  is  and  cycle.  In t h e e x p e r i m e n t a l  recordings  group.  the  g r o u p s u p e r i m p o s e d on t h e r e s u l t s o f  the c o n t r o l  the grand ensemble average o f the c o n t r o l  r e p r e s e n t ^ one s t a n d a r d d e v i a t i o n o f  the crossed l i n e  is  the control  the grand ensemble average of  group,  the  group. the  dotted  g r o u p ' s mean,  the experimental  The  and  group.  FIGURE 1  >  0 .  6  0  5  .  GRAND ENSEMBLE AVERAGES OF THE CONTROL GROUP  £ 0 . 4 0  .  3  _J  0 .  2  >  0 . 1 0 .  >  £  cn  6  0  5  0  4  0  3  0  2  0 . 0  > £  0  0  "1  1  'II  1  •I  I  "1  1  1 . 0  0 .  6  0 .  5  0 .  4  0 .  3  0 . 2  >  0 . 1 0 . 0  -1 2 0  3 0  4 0  5 0 %  C Y C L E  6 0  7 0  1  ^1  1  8 0  9 0  1 0 0  FIGURE 2 GRAND ENSEMBLE AVERAGES OF THE EXPERIMENTAL GROUP  10  2 0  3 0  4 0  5 0 %  6 0  C Y C L E  7 0  8 0  9 0  1 0 0  FIGURE 3 0 . 6  _  GRAND ENSEMBLE AVERAGES OF THE EXPERIMENTAL GROUP COMPARED TO THE CONTROL GROUP  CO  I  4 0  5 0 %  C Y C L E  6 0  1 0 0  -  A multivariate analysis  14 -  (MANOVA) o f  t h e peak EMG a m p l i t u d e s o f  m u s c l e d u r i n g s t a n c e showed no s t a t i s t i c a l l y s i g n i f i c a n t between g r o u p s ,  a n d no s t a t i s t i c a l l y s i g n i f i c a n t  vastus medial i s  and t h e v a s t u s l a t e r a l i s were c o m p a r e d .  analysis of  rectus  did reveal  a significant  difference  difference  d i f f e r e n c e when  b e t w e e n t h e peak  f e m o r i s and t h e v a s t u s m e d i a l i s  the  However,  f e m o r i s and t h e v a s t u s l a t e r a l i s and a s i g n i f i c a n t  between r e c t u s  difference  (p < 0 . 0 5 ) .  Manova  EMG P e a k A m p l i t u d e f o r V a s t u s M e d i a l i s , Vastus L a t e r a l i s  Control  df  and R e c t u s  Femoris  Group vs E x p e r i m e n t a l  Group  1,13  Between  Groups  Between  Muscles  N.S.  (p = . 1 1 4 )  Vastus L a t e r a l i s / R e c t u s  Femoris  p = .008  Vastus Medial i s ^Rectus  Femoris  p = .007  Vastus Medial i s ^Vastus L a t e r a l i s  N. S .  the  amplitudes  TABLE II  Summary o f  each  (p = .347)  -  Subsequently,  a t - t e s t was p e r f o r m e d f o r e a c h m u s c l e t o d e t e r m i n e  t h e r e w o u l d have been a s i g n f i c a n t and the e x p e r i m e n t a l tested i n the  15 -  difference  g r o u p peak EMG a m p l i t u d e s  between t h e c o n t r o l if  if  group  o n l y one m u s c l e h a d  been  experiment.  TABLE III Summary o f  T-test  Vastus Medial i s Control  Group  Experimental  Vastus Control  If  x = 457.40  d f = 16  t = 2.196  p < .025  d f = 16  t = 0.244  Femoris x = 142.82  N.S.  G r o u p "x = 137  v a s t u s l a t e r a l i s had been t h e o n l y m u s c l e t e s t e d t h e r e w o u l d  been a s i g n i f i c a n t groups  N.S.  G r o u p "x = 2 8 9 . 8 7  Group  Experimental  t = 1.241  Lateralis  Group  Rectus  d f = 17  Group 7 = 238.87  Experimental  Control  "x = 3 0 9 . 1 8  (p < 0 . 0 5 ) .  difference  b e t w e e n t h e p e a k EMG a m p l i t u d e s o f  the  have two  -  I n T a b l e IV t h e r e s u l t s dynamometer a r e  of  16  -  the muscle  s t r e n g t h t e s t s on t h e  isokinetic  summarized.  TABLE IV  Mean P e a k T o r q u e V a l u e s  (+ o n e s t a n d a r d d e v i a t i o n )  Right Quadriceps  and  a t 200°/s f o r  Hamstrings  Quadriceps  Control  Group  (n=12) Experimental (n=8)  Group  Hamstrings  Eccentric  Concentric  Eccentric  170 N.m  112.6  1 1 6 . 2 5 N.m  (+50.33)  (+22.27)  1 3 9 . 4 N.m (+47.06)  95.1  the  N.m  N.m  (+21.36)  (+26.53) 111.4  N.m  (+27.25)  Concentric 98.5  N.m  (+21.85) 9 3 . 6 - N.m (+17.94)  -  Table V i s  a summary o f  the m u l t i v a r i a t e a n a l y s i s of  t o r q u e s when c o m p a r e d by g r o u p s , by c o n t r a c t i o n  (eccentric  17 -  by m u s c l e s  t h e mean peak  ( q u a d r i c e p s and h a m s t r i n g s )  and  and c o n c e n t r i c ) .  TABLE Y  Summary o f  Manova  Peak T o r q u e V a l u e s - G r o u p by M u s c l e by  df 1,  Contraction  18  Between Groups  N.S.  (p = .230)  Between M u s c l e s  p = .001  Between C o n t r a c t i o n s  p < .001  Peak t o r q u e v a l u e s w e r e d e f i n e d a s t h e h i g h e s t r e c o r d e d v a l u e on a n y of  four  repetitions  range o f m o t i o n . the groups f o r difference  of  the muscle t e s t ,  its  T h e r e was no s t a t i s t i c a l l y s i g n i f i c a n t  t h e peak t o r q u e v a l u e s ,  b e t w e e n t h e peak t o r q u e s o f  t h e y w e r e g r o u p e d by m u s c l e . difference  regardless of  position difference  a l t h o u g h t h e r e was a  in  the  between  significant  t h e h a m s t r i n g s and t h e q u a d r i c e p s  T h e r e was a l s o a s t a t i s t i c a l l y  b e t w e e n t h e peak t o r q u e s o f c o n c e n t r i c  one  when  significant  and e c c e n t r i c  contractions.  -  Hamstrings/quadriceps torque values of i s a summary o f  (H/Q)  18 -  r a t i o s were c a l c u l a t e d from the  peak  b o t h t h e e c c e n t r i c and c o n c e n t r i c c o n t r a c t i o n s . t h e t - t e s t t o compare groups f o r each o f  the  Table  VI  ratios.  TABLE VI Summary o f  T-test  P e a k T o r q u e - A n a l y s i s By  Ratios  H/Q RATIO CONCENTRIC CONTROL GROUP  x = .88  EXPERIMENTAL GROUP  d f = 18  t = -1.60  N.S.  (p = .127)  t = -1.06  N.S.  (p = .304)  x = 1.02  H/Q RATIO ECCENTRIC CONTROL GROUP  x = .73  EXPERIMENTAL GROUP  d f = 18  x = .87  T h e r e was no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e b e t w e e n t h e f o r e i t h e r t h e c o n c e n t r i c o r e c c e n t r i c H/Q  ratios.  groups  - 19 -  Table VII  is  a summary o f  t h e number o f  deviations of  a v e r a g e s o u t s i d e o f + one s t a n d a r d d e v i a t i o n o f for  the experimental  group and t h e c o n t r o l  d i s t r i b u t i o n 68.26% o f  the subjects'  the  the c o n t r o l  group.  ensemble  g r o u p ' s mean,  In a normal  (Gaussian)  EMG p r o f i l e s w o u l d l i e w i t h i n + o n e  s t a n d a r d d e v i a t i o n a n d 15.87% w o u l d be a b o v e one s t a n d a r d d e v i a t i o n 15.87% w o u l d be l e s s r e s u l t s of  t h a n one s t a n d a r d d e v i a t i o n .  the c o n t r o l  group f o l l o w e d a normal  a m p l i t u d e s d u r i n g s t a n c e phase f o r a l l rectus  femoris  from each s u b j e c t  from each s u b j e c t  the control determine i f  group's  i n t h e EMG p r o f i l e s  d i s t r i b u t i o n , t h e EMG peak  in the control  group were compared t o  group were compared  g r a n d e n s e m b l e a v e r a g e +_ one s t a n d a r d d e v i a t i o n  of  the group of  ( o u t s i d e + one s t a n d a r d  subjects with patellofemoral  s y n d r o m e t h a n one w o u l d e x p e c t i n a n o r m a l  for the  S u b s e q u e n t l y t h e same EMG  i n the experimental  t h e r e w e r e more d e v i a t i o n s  the  t h r e e m u s c l e s and s w i n g phase  mean EMG p a t t e r n +_ one s t a n d a r d d e v i a t i o n . amplitudes  To d e t e r m i n e i f  while  distribution.  to to  deviation) pain  - 20 -  TABLE VII Deviations of the EMG Peak Amplitudes Compared to the Control Group's Grand Ensemble Average  Control Group  Experimental Group  w i t h i n +_ 1 S . D . above 1 S . D . below 1 S . D .  6/11 * 3/11 2/11  6/8  Rectus femoris ( s t a n c e phase)  within + 1 S.D. above 1 S . D . below 1 S . D .  5/11 4/11 2/11  4/7 2/7 1/7  (swing  within + 1 S.D. above 1 S . D . below 1 S . D .  6/11 3/11 2/11  2/7  within + 1S.D. above 1 S . D . below 1 S.D.  6/10 2/10 2/10  4/8  Vastus medial i s ( s t a n c e phase)  phase)  Vastus l a t e r a l i s ( s t a n c e phase)  Six subjects  2/8  5/7  4/8  o u t o f 11 r e m a i n e d w i t h i n + o n e s t a n d a r d d e v i a t i o n  (S.D.)  -  21 -  DISCUSSION  Group Mean Muscle A c t i v a t i o n Patterns The r e s u l t s o f quadriceps muscles lateralis) w i t h normal  of  the comparison of  the grand ensemble averages of  (the vastus medial i s ,  rectus  subjects with patellofemoral  f e m o r i s and t h e  vastus  p a i n syndrome t o t h o s e  subjects  l o w e r e x t r e m i t y a l i g n m e n t a n d no k n e e p a i n , showed t h a t  two g r o u p s h a d t h e same a v e r a g e p a t t e r n s o f m u s c l e a c t i v i t y w h i l e on a t r e a d m i l l , v a r y i n g o n l y  in regard to amplitude  (Figure 3 ) .  a m p l i t u d e d i f f e r e n c e was n o t s t a t i s t i c a l l y s i g n i f i c a n t mean m u s c l e p a t t e r n s o f standard deviation of  the experimental  the c o n t r o l  The mean m u s c l e p a t t e r n s quadriceps  group.  r e v e a l e d t h a t t h e l a r g e s t amount  press)  knee f l e x i o n  1982; R o b e r t s o n ,  in press).  t h a t from mid-stance u n t i l  stance i n both the c o n t r o l  (Winter,  medial i s  during early  at this  stance,  Winter  group  and  (1983) and R o b e r t s o n  (in  and  to extend the  study i t would appear t h a t the  since rectus  running, E l l i o t t  and  energy  l a t e - s t a n c e the quadriceps continue  time i n the g a i t c y c l e .  muscles during t r e a d m i l l  the  contracting  and v a s t u s l a t e r a l i s c o n t r i b u t e most t o t h e a c t i v i t y o f  quadriceps activity  this  as  an  1983; Robertson  be a c t i v e b u t t h e y a r e c o n t r a c t i n g c o n c e n t r i c a l l y F r o m t h e EMG r e s u l t s o f  peak  of  have a l s o r e p o r t e d f r o m t h e i r power a n a l y s e s o f j o g g i n g  running,  The  II)  This burst of a c t i v i t y coincides with  to control  running  g r o u p r e m a i n e d w i t h i n _+ one  a b s o r b i n g phase by t h e knee e x t e n s o r s as t h e y a r e eccentrically  (Table  the  g r o u p ' s mean.  a c t i v i t y occurred in early  the experimental  Taunton,  the  f e m o r i s showed l e s s  I n t h e i r EMG s t u d y o f and B l a n k s b y  (1979)  knee. vastus the muscle the  also  leg  to  -  reported the vastus medial i s  22 -  and t h e v a s t u s l a t e r a l i s t o have  a m p l i t u d e s d u r i n g s t a n c e phase than r e c t u s differed  from t h i s  femoris,  however,  h a v e t h e m o s t EMG a c t i v i t y .  It  this  is  n o t known why t h e r e may be  i n the amplitudes of  as E l l i o t t  and B l a n k s b y a l s o had t h e i r f e m a l e s u b j e c t s  form of  is  that E l l i o t t  this  (aged 20-28 y e a r s )  study u t i l i z e d l i n e a r envelope  and B l a n k s b y  activity  i n the vastus medial i s  the muscle's c o n t r i b u t i o n rectus  v a s t u s l a t e r a l i s have o n l y one - i s  because i t  profiles  from t h i s  activity  p a t t e r n of  vastus medial i s statistically  the a c t i v i t y of  is  and  a two-joint  curve The  muscle.  are  not  However, in  rather  t h e EMG the  f e m o r i s d u r i n g r u n n i n g g a i t compared t o  difference  bursts  the  s p e c i f i c muscles but  a muscle group.  and t h e v a s t u s l a t e r a l i s .  significant  vastus  f e m o r i s - h a v i n g two  s t u d y i n d i c a t e t h a t t h e r e was a d i f f e r e n c e rectus  rectus  to hip f l e x i o n .  (1983) have r e p o r t e d t h a t s u r f a c e e l e c t r o d e s  s e n s i t i v e e n o u g h t o d e p i c t t h e EMG p a t t e r n o f  in  second  of a c t i v i t y during the g a i t c y c l e , while the vastus medial i s  are r e p r e s e n t a t i v e of  between  processing.  or the  (1979) a l s o r e p o r t e d t h i s  d i f f e r e n t muscle a c t i v a t i o n pattern of  Schwab e t a l .  to  a n d B l a n k s b y u s e d a v e r a g e d i n t e g r a t e d EMG a s a  f e m o r i s b u t no f u r t h e r a c t i v i t y  which they suggested i s  have  studies,  The m a j o r d i f f e r e n c e  D u r i n g s w i n g p h a s e , t h e r e was a s e c o n d b u r s t o f  Elliott  to  the  t h e two m u s c l e s b e t w e e n t h e two  a t a p p r o x i m a t e l y 12 k m / h .  processing while  lateralis.  results  study found the vastus l a t e r a l i s  difference  the s t u d i e s  their  study i n t h a t they reported the vastus medial i s  t h e g r e a t e s t peak a m p l i t u d e w h i l e  r u n on a t r e a d m i l l  larger  the  F u r t h e r m o r e , t h e r e was a  b e t w e e n t h e p e a k EMG a m p l i t u d e s  of  - 23 -  rectus  f e m o r i s and t h e v a s t u s l a t e r a l i s  the vastus medial i s  (p = 0 . 0 0 7 )  I n summary, a c o m p a r i s o n o f mental  group t o the c o n t r o l  be s i m i l a r .  Differences  were f o u n d ; of  d u r i n g s t a n c e phase  group.  statistically  This lack  reasons.  of  t h e two  than t h a t of  r u n n e r s w i t h PFPS a r e t o o s u b t l e f o r  group of  1980; Fox,  a l t e r e d g a i t of timing of usually  1975).  d i f f e r e n c e may h a v e  Richards et a l .  however,  in this  subjects.  condition  Clinically  individual's  (LeVeau &  in  the the  and i n t h e c a s e o f  not  the  running.  averages the d i f f e r e n c e s  i t w o u l d be more b e n e f i c i a l  r e s u l t s compared t o a 'norm'  patient differs, problem.  only  the  p a t i e n t s w i t h PFPS i s  I t may a l s o be t h a t a v e r a g i n g t h e EMG p a t t e r n s o f clinical  group  associated  r e s u l t i n changes  the g a i t of  s t u d y many w e r e s t i l l  the  (1985) have s u g g e s t e d t h a t  s e v e r e l y a f f e c t e d by t h e i r c o n d i t i o n ,  subjects  in  r u n n e r s and a  vastus medialis  a severely d i s a b l e d person w i l l  t h e EMG p a t t e r n s ,  the  be  l i t e r a t u r e h a s s u g g e s t e d t h a t t h e r e may be q u a d r i c e p s w e a k n e s s  Rogers,  groups  t h e EMG t o r e c o r d e v e n t h o u g h  w i t h P F P S , a n d more s p e c i f i c a l l y w e a k n e s s o f  to  patterns  I t may be t h a t t h e d i f f e r e n c e s  muscle a c t i v a t i o n p a t t e r n s between a ' n o r m a l ' of  the patterns  the muscle a c t i v i t y  a statistical  and  the e x p e r i -  t h e s e d i f f e r e n c e s were n o t found t o  significant.  femoris  II).  the curves of  g r o u p w e r e o b s e r v e d t o be l e s s  resulted for different  (Table  group r e v e a l e d the phasing of  in the amplitude of  However,  and r e c t u s  t h e a v e r a g e EMG p a t t e r n s o f  i n p a r t i c u l a r the amplitudes of  the experimental  control  (p = 0 . 0 0 8 )  individuals with  o f each o f to analyze  those each  t o d e t e r m i n e how o r i f  the  a n d t h e n t r e a t m e n t c o u l d be d i r e c t e d t o c o r r e c t i n g  the  a  - 24 -  Peak Concentric and Eccentric Torque Values of the Knee Extensor and F1exor Muscles The r e s u l t s difference of  show t h a t t h e r e was no s t a t i s t i c a l l y  between t h e s u b j e c t s w i t h PFPS and t h e group o f s u b j e c t s  knee p a i n and w i t h  eccentric  significant  normal  free  a l i g n m e n t when t h e mean peak c o n c e n t r i c a n d  t o r q u e v a l u e s were compared, f o r both t h e r i g h t q u a d r i c e p s and  hamstrings. To d a t e t h e r e h a v e b e e n f e w s t u d i e s o f t h e q u a d r i c e p s torques only  at certain velocities  i n y o u n g women, a n d o f t h e s e f e w t h e y  i n v e s t i g a t e d concentric muscle a c t i v i t y .  s t u d i e d 50 n o n - a t h l e t i c angular v e l o c i t i e s .  f e m a l e s u b j e c t s a g e d 25 - 3 4 y e a r s , a t  ( 7 7 N.m) f o r t h e q u a d r i c e p s  be 7 8 . 7 f t - l b  (1981) three  and 45 f t - l b  ( 6 1 N.m)  D i b r e z z o e t a l . (1985) s t u d i e d 241 n o n - a t h l e t i c  f e m a l e s a g e d 18 - 28 y e a r s b u t o n l y a t 6 0 ° / s . 13 f e m a l e c o l l e g e  Wyatt & Edwards  have  T h e y f o u n d a t 180°/s t h a t t h e g r o u p ' s mean p e a k  t o r q u e s w e r e 57 f t - l b s . for the hamstrings.  and h a m s t r i n g s  basketball  Berg e t a l . (1985)  studied  p l a y e r s a n d f o u n d t h e i r mean peak t o r q u e s  ( 107 N.m) f o r t h e r i g h t k n e e e x t e n s o r s a n d 5 6 . 3 f t - l b  ( 76 N.m) f o r t h e r i g h t k n e e f l e x o r s a t 1 8 0 ° / s .  Richards  (1981)  studied  19 f e m a l e s w h o s e a g e s r a n g e d f r o m 21 - 6 0 y e a r s w h o s e a c t i v i t y l e v e l s n o t s t a t e d , a n d s h e r e p o r t e d t h e i r mean peak t o r q u e  f o r the quadriceps  be 8 0 . 9 N.m a n d f o r t h e h a m s t r i n g s t o be 4 8 . 1 N.m, a t 1 8 0 ° / s . these studies  to  All  support.  Each group o f i n v e s t i g a t o r s a l s o p r e s e n t e d t h e i r r e s u l t s as a hamstrings/quadriceps  ratio  (H/Q r a t i o )  - t h a t i s t h e peak t o r q u e  to  of  used t h e Cybex I I i s o k i n e t i c dynamometer, and i n each  t h e s u b j e c t s were t e s t e d i n s i t t i n g w i t h a back  were  of  case  - 25 -  concentric  k n e e f l e x i o n d i v i d e d by t h e p e a k t o r q u e o f c o n c e n t r i c  extension.  knee  I n t h i s c a s e a t an a n g u l a r v e l o c i t y o f 180°/s W y a t t & E d w a r d s  reported a ratio of ratio of  .60.  activity  levels  . 7 9 , Berg e t a l . reported  The d i f f e r e n c e  .72 and R i c h a r d s  found a  i n t h e r a t i o ' s may be d u e t o t h e  and t h e d i f f e r e n t  age g r o u p s o f t h e s u b j e c t s  different  i n each  study. The t e s t i n g f o r t h i s velocity  s t u d y was p e r f o r m e d o n a KINCOM a t a n a n g u l a r  o f 200°/s w i t h t h e s u b j e c t s  backrest.  s e a t e d a n d s u p p o r t e d by a  T h e g r a v i t y c o r r e c t i o n o p t i o n was n o t u s e d s o t h a t  c o m p a r i s o n s c o u l d be made t o o t h e r s t u d i e s . r u n n i n g a minimum o f 16 km week  T h o s e f e m a l e s who w e r e  (10 m i l e s / w e e k )  a n d who w e r e f r e e o f  e x t r e m i t y a b n o r m a l i t i e s a n d p a i n h a d a c o n c e n t r i c mean p e a k t o r q u e 1 1 2 . 6 N.m f o r t h e r i g h t q u a d r i c e p s The mean H/Q r a t i o o f t h i s Nosse  conditions.  g r o u p was . 8 8 .  population  v a r i e d from  He s u g g e s t e d t h a t  velocity of the t e s t ,  characteristics,  . 9 0 , under a v a r i e t y  of  i t i s necessary to consider the angular  t h e t e s t i n g p o s i t i o n , t h e equipment used and t h e  Appen & Duncan (1986) e l a b o r a t e  f u r t h e r on s u b j e c t  suggesting that sex, age, a c t i v i t y l e v e l  also influence  the torque values.  research that at high concentric  that fibre  .43 -  r a t i o s and  b e i n g i n v e s t i g a t e d b e f o r e comparing o r g e n e r a l i z i n g from one  study t o another.  significant  of  hamstrings.  ( 1 9 8 2 ) r e v i e w e d 50 r e p o r t s o f h a m s t r i n g s / q u a d r i c e p s  found t h a t the r a t i o s  activity  a n d 9 8 . 5 N.m f o r t h e r i g h t  lower  difference  and type o f  They have f o u n d i n  velocities  their  ( 3 0 0 ° / s ) , t h e r e was a  b e t w e e n t y p e s o f c o m p e t i t o r s , w h i c h may i n d i c a t e  type composition or f i b r e  size  is a factor  i n peak  torque  - 26 -  values.  Furthermore,  torques. 300°/s)  they noted t h a t g r a v i t y a f f e c t s  A t each o f f o u r a n g u l a r v e l o c i t i e s  t h e measured  ( 6 0 ° / s , 1 8 0 ° / s , 240°/s a n d  t h e g r a v i t y c o r r e c t e d peak e x t e n s o r t o r q u e s w e r e  increased  compared t o t h e n o n g r a v i t y c o r r e c t e d t o r q u e s , w h i l e t h e g r a v i t y flexor  peak t o r q u e s  significant for  decreased.  difference  gravity, with  These d i f f e r e n c e s  corrected  resulted in a  b e t w e e n t h e H/Q r a t i o s c o r r e c t e d a n d n o t c o r r e c t e d  the gravity corrected torques  lower.  A s more s t u d i e s a r e p u b l i s h e d i t becomes a p p a r e n t t h a t t h e r e i s a n e e d for  b a s e l i n e o r normal  data from w e l l  defined testing protocols, results of this athletic  females  delineated populations with  s o t h a t c o m p a r i s o n s c a n be m a d e .  s t u d y ' s group o f female runners i n Wyatt & Edward's  study,  well  Comparing t h e  ( w i t h o u t PFPS)  t o the non-  t h e peak t o r q u e v a l u e s f o r t h e  r u n n e r s w e r e h i g h e r f o r b o t h t h e q u a d r i c e p s a n d h a m s t r i n g s , a s w o u l d be e x p e c t e d comparing a c t i v e and n o n - a c t i v e p o p u l a t i o n s . , coworkers'  study the female b a s k e t b a l l  than the r e c r e a t i o n a l the f a c t  runners from t h i s  g r e a t e r s p r e a d between them. basketball  p l a y e r s was l e s s  98.5 N.m).  equipment  p l a y e r s h a d a mean H/Q r a t i o  less  s t u d y , w h i c h was d e m o n s t r a t e d by  t h a t t h e mean p e a k e x t e n s o r t o r q u e s w e r e n e a r l y t h e same ( 1 0 7 N.m  c o m p a r e d t o 1 1 2 . 6 N.m r e s p e c t i v e l y )  activity  In Berg &  b u t t h e mean p e a k f l e x o r t o r q u e s  T h e mean p e a k f l e x o r t o r q u e o f t h e than t h a t of the runners  ( 7 6 N.m c o m p a r e d t o  This comparison i s i n d i c a t i v e o f d i f f e r e n c e s  and a c t i v i t y l e v e l s . (i.e.,  differences.  had a  However,  i n types  of  one c a n n o t r u l e o u t t h a t t y p e s o f  - C y b e x v s K i n c o m ) may a l s o be c o n t r i b u t i n g t o t h e  -  27 -  Another purpose of e s t a b l i s h i n g normative data i s c a n be made t o c l i n i c a l r e s u l t s of  findings.  rehabilitation  Campbell  so t h a t  and G l e n n  comparisons  (1982) s t u d i e d  i n male and f e m a l e p a t i e n t s w i t h  chondromalacia,  a n d o t h e r k n e e p r o b l e m s , a n d r e p o r t e d t h e mean peak t o r q u e s o f muscles of  the i n v o l v e d l e g before  t r e a t m e n t t o be l e s s  muscles of  the non-involved l i m b .  Richards et a l .  mean p e a k k n e e e x t e n s o r a n d f l e x o r t o r q u e s o f patients  (functional  differences  class  II)  to a 'normal'  b e t w e e n t h e two g r o u p s .  p a t i e n t s w i t h PFPS ( T a b l e  IV)  control  The r e s u l t s o f  group  cause of  (Table V ) .  p a i n and t h e a c t i v i t y  dysfunction of  disease of  this  relatively  significant  s t u d y have  forth  those  from  the  indicate  that  the  these studies  a l l o w e d by a d i s a b i l i t y  or  system are important c o n s i d e r a t i o n s the  l e s s muscle  t h o s e p a t i e n t s w i t h PFPS a r e  t h e need t o d e t e r m i n e what i s  clinically  in  disabling  a c t i v e a l t h o u g h t h e y may n o t be r u n n i n g a s a f o r m o f  This brings  shown  different  One w o u l d e x p e c t p a t i e n t s w i t h  group, while  the  and h a m s t r i n g s i n  r h e u m a t o i d a r t h r i t i s t o have s i g n i f i c a n t l y  compared t o a c o n t r o l  each  level  same  arthritic  and f o u n d  n o t t o be s i g n i f i c a n t l y  the musculoskeletal  analyzing test results.  group,  the quadriceps  knee  (1985) compared  The r e s u l t s o f  t h e c o n c e n t r i c mean peak t o r q u e s o f  the  than the  rheumatoid  the  strength  still exercise.  significant  for  condition. G o s l i n and C h a r t e r i s  i n d i c a t o r of c l i n i c a l potential velocity  for  injury.  increases  the quadriceps  ( 1 9 7 9 ) b e l i e v e t h a t t h e H/Q  r a t i o c o u l d be an  a b n o r m a l i t y a t t h e knee o r an i n d i c a t o r o f This ratio  the d i f f e r e n c e s  is  speed-specific,  as t h e  between t h e c o n c e n t r i c  and h a m s t r i n g s d e c r e a s e s  the  angular  peak t o r q u e s  ( W y a t t and E d w a r d s ,  1981).  The  of  - 28 -  concentric  H/Q r a t i o f r o m t h i s  a n g u l a r v e l o c i t y o f 200°/s,  .88 f o r t h e c o n t r o l  s u g g e s t s t h a t t h e peak t o r q u e  b e t w e e n t h e two m u s c l e g r o u p s The c o n c e n t r i c  study of  g r o u p a t an differences  i s not great.  H/Q r a t i o f r o m t h o s e s u b j e c t s w i t h P F P S was 1 . 0 2  V I ) w h i c h was n o t s t a t i s t i c a l l y d i f f e r e n t  from the c o n t r o l  i s outside  (1982).  o f t h e r a n g e r e p o r t e d by N o s s e  (Table  group b u t which  T h i s H/Q r a t i o  suggests  t h a t on t h e a v e r a g e t h e s u b j e c t s w i t h P F P S h a d s i m i l a r s t r e n g t h i n t h e hamstrings as i n the q u a d r i c e p s . The o n l y e c c e n t r i c the l i t e r a t u r e flexors.  i n v e s t i g a t i o n o f i s o k i n e t i c muscle a c t v i t y found  i s t h a t by Komi  force  results of this the control  decreased and t h e e c c e n t r i c study,  group and t h e e x p e r i m e n t a l  suggest that f u r t h e r  increased, the  force  increased.  From t h e  a t 2 0 0 ° / s , t h e e c c e n t r i c mean peak t o r q u e s  c o n c e n t r i c mean p e a k t o r q u e s  velocity  ( 1 9 7 3 ) d u r i n g w h i c h he s t u d i e d t h e e l b o w  He f o u n d t h a t a s v e l o c i t y o f c o n t r a c t i o n  concentric  (Table  study i s necessary t o determine i f  as i n t h e m u s c l e s o f normal  in clinical healthy  f o r both  group were h i g h e r than t h e  f o r t h e same m u s c l e s  relationship exists  conditions  IV).  The r e s u l t s  a similar  ( s u c h as PFPS)  forceas w e l l  subjects.  A l t h o u g h t h e r e a r e no o t h e r s t u d i e s w h i c h h a v e r e p o r t e d e c c e n t r i c torques of the quadriceps  in  and h a m s t r i n g s w i t h which t o compare,  is  v a l u a b l e t o note the f i n d i n g s  from t h i s  the experimental  I V ) s o t h a t f u t u r e c o m p a r i s o n s c a n be m a d e .  Similarly  group  (Table  study f o r the control  it  peak  t h e r e h a s b e e n no l i t e r a t u r e on t h e e c c e n t r i c  was n o t a s t a t i s t i c a l l y s i g n i f i c a n t  difference  when c o m p a r i n g e c c e n t r i c  in this  H/Q r a t i o s  group and  H/Q r a t i o .  between t h e two  study,  however,  as  There  groups  -  previously  stated i t  is  useful  29 -  to note the r a t i o s  (Table VI)  for  future  comparisons. It  is  i n t e r e s t i n g to note from the r e s u l t s  e c c e n t r i c mean peak t o r q u e v a l u e s o f groups are c l o s e r t o g e t h e r w h i l e  the hamstrings f o r both  i)  t h e mean c o n c e n t r i c  and  subject  t h e mean peak t o r q u e s o f e a c h g r o u p  t h e q u a d r i c e p s a r e much f a r t h e r a p a r t I n summary, t h e r e s u l t s o f  that the c o n c e n t r i c  (Table  our i s o k i n e t i c  H/Q r a t i o  IV). t e s t i n g have r e v e a l e d t h a t  (1.02) of  those subjects with  was a b o v e t h e r a n g e t h a t h a s b e e n r e p o r t e d i n t h e This abnormally high r a t i o  for  -  PFPS  literature.  s u g g e s t e d t h a t t h e mean peak t o r q u e  t h e h a m s t r i n g s was n e a r l y t h e same a s t h e mean peak t o r q u e o f  of the  quadriceps.  ii)  a t an a n g u l a r v e l o c i t y o f 200°/s t h e c o n c e n t r i c r a t i o s were d i f f e r e n t ,  due t o t h e f a c t  e c c e n t r i c mean p e a k t o r q u e s o f  and e c c e n t r i c  t h a t the c o n c e n t r i c  the h a m s t r i n g s were  together while  the c o n c e n t r i c  and e c c e n t r i c  the quadriceps  had a g r e a t e r s p r e a d between  and  closer  mean p e a k t o r q u e s them.  H/Q  of  - 30 -  iii)  when c o n s i d e r i n g c l i n i c a l that c l i n i c a l  significance  f i n d i n g s compared t o norms, i t differs  from s t a t i s t i c a l  a n d t h a t e a c h c o n d i t i o n may h a v e a d i f f e r e n t c a n c e d e p e n d i n g upon p a i n , m u s c u l o s k e l e t a l of  disability.  level  appears  significance, of  signifi-  i n v o l v e m e n t and  degree  - 31 -  CONCLUSIONS  The r e s u l t s o f t h i s 1.  From a v i s u a l experimental  s t u d y h a v e shown  that:  a n a l y s i s o f t h e mean EMG p r o f i l e s group superimposed on t h e c o n t r o l  of the g r o u p ' s mean EMG  p a t t e r n + o n e s t a n d a r d d e v i a t i o n , t h e mean m u s c l e a c t i v i t y o f t h e vastus medial i s , similar  r e c t u s f e m o r i s and t h e v a s t u s l a t e r a l i s was  ( w i t h i n +^ o n e s t a n d a r d d e v i a t i o n )  patellofemoral p a i n and w i t h running.  f o r subjects  p a i n syndrome compared t o s u b j e c t s normal  lower extremity alignment,  Additionally,  a multivariate analysis  with  f r e e o f knee  during  treadmill  (MANOVA), o f t h e  peak EMG a m p l i t u d e s r e v e a l e d t h a t t h e r e was n o t a s i g n i f i c a n t difference 2.  between t h e two g r o u p s .  T h e mean EMG p a t t e r n f o r r e c t u s different that  f e m o r i s f r o m b o t h g r o u p s was  from t h e vastus medial i s and t h e vastus l a t e r a l i s ,  rectus  femoris had a b u r s t o f a c t i v i t y during stance  and a s e c o n d b u r s t o f a c t i v i t y d u r i n g s w i n g , w h i l e  in  phase  the vastus  medial i s and t h e v a s t u s l a t e r a l i s had o n l y one b u r s t o f a c t i v i t y during stance phase. significant  difference  Furthermore,  t h e r e was a s t a t i s t i c a l l y  i n t h e peak EMG a m p l i t u d e s o f r e c t u s  f e m o r i s compared t o t h e v a s t u s medial i s and r e c t u s compared t o t h e v a s t u s l a t e r a l i s  3.  during stance  T h e r e w a s no s t a t i s t i c a l l y s i g n i f i c a n t s u b j e c t s w i t h and w i t h o u t  phase.  difference  patellofemoral  femoris  between t h e  p a i n s y n d r o m e when  their  - 32 -  mean peak c o n c e n t r i c  and e c c e n t r i c  t o r q u e v a l u e s were  f o r t h e r i g h t h a m s t r i n g s and q u a d r i c e p s .  Similarly a t-test  t h e peak t o r q u e v a l u e s e x p r e s s e d a s a h a m s t r i n g s / ratio  showed t h a t t h e r e was n o t a s i g n i f i c a n t  the groups.  However,  t h e mean c o n c e n t r i c  s u b j e c t s w i t h P F P S was 1.02 w h i c h w h i c h has been r e p o r t e d i n t h e  is  of  quadriceps  difference  H/Q r a t i o f r o m  outside of  literature.  compared  between the  t h e normal  range  -  33 -  RECOMMENDATIONS  B a s e d on t h e u n d e r s t a n d i n g g a i n e d a s a r e s u l t o f t h i s following  1.  recommendations a r e suggested f o r f u t u r e  The s i z e o f t h e c o n t r o l  study, the  investigations.  g r o u p m u s t b e g r e a t e r s o t h a t t h e mean  EMG p r o f i l e + o n e s t a n d a r d d e v i a t i o n f r o m e a c h m u s c l e w o u l d less  2.  v a r i a b i l i t y and b e t t e r r e p r e s e n t a normal  distribution.  Activities  such a s ascending o r descending s t a i r s o r s q u a t t i n g  may r e v e a l  greater differences  subjects with patellofemoral group, as t h e j o i n t joint  i n t h e EMG p r o f i l e s  o f those  p a i n syndrome compared t o a c o n t r o l  reaction forces  through t h e patellofemoral  a r e known t o b e h i g h d u r i n g t h o s e a c t i v i t i e s  often complain o f pain during those  3.  have  and p a t i e n t s  activities.  By r e c o r d i n g t h e EMG a c t i v i t y o f t h e m u s c l e s s i m u l t a n e o u s l y the muscle t e s t i n g and then r e c o r d i n g t h e muscle a c t i v i t y a functional  a c t i v i t y without  with during  removing t h e e l e c t r o d e s , t h e  i n v e s t i g a t o r would be a b l e t o d e t e r m i n e t h e p e r c e n t a g e o f m u s c l e activity  4.  d u r i n g a c t i v i t y compared t o a maximal  strength  test.  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J . o f O r t h o p a e d i c and S p o r t s Physical Therapy. 3: 4 8 - 5 6 . 1981.  APPENDIX 1 TABLE VIII Clinical  Characteristics  CS  CR  GG  20 155 60.9 19  22 155 54.5 24  20 167.5 58.1 56  21 160 54.5 16  Knee p a i n  no  no  no  no  Knee alignment  valgus  valgus  valgus  12°  12°  Rearfoot varus alignment  < 4°  F o r e f o o t varus a l i gnment  Age ( y e a r s ) H e i g h t (cm) Weight (kg) Km/wk r u n n i n g  Q-angle  Overpronation Leg-1ength  JF  of  the Control  Group  Subjects  LS  MR  PB  PW  SL  SO  27 165 60 56  32 170 53.6 24  25 172.5 56.4 32  21 160 53.2 24  29 165 63.6 40  23 175 63.6 40  no  no  no  no  no  no  no  varus  varus  varus  varus  valgus  varus  valgus  no  SP 25 170 54 19  VA 26 167.5 53.2 48  varus  varus  10°  12°  12°  15°  15°  14°  12°  13°  12°  10°  < 4°  < 4°  < 4°  < 3°  < 4°  < 4°  < 4°  < 4°  < 4°  < 4°  < 4 °  < 4°  < 4°  < 4°  < 4°  < 3°  <4°  < 4°  < 4°  < 2°  < 3°  < 3°  < 4  no  mild  no  mild  mild  no  no  mild  no  no  no  no  equal  equal  equal  R<L 1cm*  equal  equal  equal  equal  equal  equal  equal  equal  0  r i g h t l e g s h o r t e r than l e f t by one c e n t i m e t e r  CO  - 40 -  Individual Ensemble Averages from the Control Group  F i g u r e s 4 t o 15 a r e t h e e n s e m b l e a v e r a g e s o f t h e l i n e a r e n v e l o p e EMG of  vastus medialis  (V.L.)  (V.M.), rectus  f o r each s u b j e c t  femoris  i n the control  the ensemble average w h i l e  Toe-off  group.  the dotted l i n e s  One h u n d r e d p e r c e n t o f t h e g a i t c y c l e heel-strike.  and vastus  lateralis  The s o l i d l i n e  represents  a r e +_ o n e s t a n d a r d  i s from h e e l - s t r i k e t o  i s i n d i c a t e d by A .  measured i n m i l l i v o l t s .  (R.F.)  deviation.  ipsilateral  The a m p l i t u d e o f t h e c u r v e s  is  FIGURE 4  1  T  r  SUBJECT50 CR. 60 40 %  C Y C L E  100  FIGURE 5  ^•inii-iMMiiHU.j  \\\&WA  > 0.4 J e ^0.3 . • 0.2 • 0.1 J  10  20  30  40 %  50  60  C Y C L E  SUBJECT CS.  70  80  90  100  FIGURE 6  3 0  4 0 %  5 0  6 0  C Y C L E  SUBJECT GG  7 0  8 0  9 0  1 0 0  FIGURE 7  a. r\ 0 > ^  .  0 0 .  6 5  _  . 4  _  3  _  %  C Y C L E  SUBJECT J F  FIGURE 8  0 . 6  r\  0 . 5  >  0  £  >  3  _  2  _  1  _  0  0  _  0  6  _  0 . 5  _  ^ >  C  > £  >  .4 _  0  0 .  ^  _  4 _  0 . 3  _  2  _  4^ in  1  -  0  0  0  0  6  _  0  5  _  0  4 _  0  3  _  0  2  _  0 .  1  _  0 . 0 0  5 0 %  6 0  C Y C L E  SUBJECT LS  7 0  T  T  8 0  9 0  1 0 0  FIGURE 9  T 4 0  5 0 %  6 0  C Y C L E  SUBJECT MR  1 0 0  FIGURE 10  r\ > ^  0 . 5  _  0 . 4  _  0 . 3  _  • 0 . 2 0 . 1  a.  J  0 . 0  "1 0  1 0  2 0  3 0  4 0  5 0 %  6 0  C Y C L E  SUBJECT PB  7 0  1 8 0  "•"II 9 0  1 0 0  FIGURE  0.0 0.6 ^ 0.5 _ > 0.4_ £ ^0.3 •0.2 J 0. 1 J ^ 0.5 J > 0. 4 ^ 0.3 _ ^•0.2. > 0 . 1 0.0 0  !  !  11  1 ^* J***^tiKjiiiiiiiii| H  ii«ij.i-M:i.:|imrH«*p  J  liil;iii|iiniiiii|ii  40 50 60 % CYCLE SUBJECT PW  70  80  90  100  FIGURE  12  SUB.JECT SL  FIGURE 13  0.6 r\ 0 . 5 _ > 0 .4 _ E  ^ 0.3 _  ^ 0 .5 _ > 0.4 _  % CYCLE SUBJECT SO  FIGURE 14  0.6 ^ 0.5 > 0.4 _ ^ 0.3 _  J  ^ 0.5 _ > 0 .4 _ ^ 0.3 _  0.5 _ > 0 .4 _ ^ 0.3 _ rx  10  20  30  40 50 60 % CYCLE SUBJECT SP  70  80  90  100  FIGURE 15  0*6 . '  1  1  1  n  1  %  1  CYCLE  SUBJECT VA  '  ~~T  1  1  -  53 -  APPENDIX 2  TABLE IX Individual  Peak T o r q u e V a l u e s f o r t h e R i g h t  Leg  a t 200°/s  Quadriceps  Hamstrings  SUBJECTS Control  Group C o n c e n t r i c  CR CS GG JF LS MR PB PW SL SO SP VA  imental SC HB EC TR RW SS JH JG  100 98 90 137 109 122 114 90 116 129 164 82  Eccentric  Concentric  Eccentric  166 197 72 172 104 198 202 169 124 193 276 168  77 104 88 139 92 103 127 74 73 115 118 72  99 132 97 154 110 125 150 92 63 135 142 96  144 84 80 110 168 233 164 132  107 111 89 66 122 96 85 73  138 120 91 66 158 121 105 92  Group 87 128 76 78 90 114 121 67  - 54 -  TABLE X  Individual  Concentric  and  Hamstrings/Quadriceps F o r The R i g h t  Eccentric Ratios  Leg  SUBJECTS Control  Group  Concentric  CR CS GG JF LS MR PB PW SL SO SP VA  Experimental SC HB EC TR RW SS JH JG  Eccentric  .77 1.06 .98 1.01 .84 .84 1.11 .82 .63 .89 .72 .88  .60 .67 1.35 .90 1.06 .63 .74 .54 .51 .70 .51 .57  1.23 .87 1.17 .85 1.36 .84 .70 1.09  .95 1.43 1.14 .60 .94 .52 .64 .70  Group  - 55 -  APPENDIX 3  Individual Muscle A c t i v a t i o n Patterns The c l i n i c a l pain,  plus  Table  XI.  examination of  the r e s u l t s of  the e i g h t  subjects with  patellofemoral  t h e i r dynamic s t r e n g t h t e s t i n g i s  summarized  in  TABLE XI of  C l i n i c a l C h a r a c t e r i s t i c s and Dynamic S t r e n g t h t h o s e S u b j e c t s W i t h R i g h t P a t e l l o f e m o r a l P a i n Syndrome  SC  HB  EC  TR  RW  SS  JH  JG  35 23 24 22 15 20 22 36 165 167.5 160 167.5 152.5 155 167.5 160 61.4 50 56.8 63.6 53.6 54.5 59.1 61.4 24 16 24 19 8 19 40 24 m e d i a l m e d i a l m e d i a l i n f r a m edial medial medial i n f r a r e t r o r e t r o p a t e l l a r r e tropatellar pate! 1 ar lateral patellar patellar - duration 6-7 y r s 5 y r s 3 mo 2 yrs 2-3 y r s 6 y r s 6 mo 2 yrs - w i t h r u n n i ng y e s yes yes yes yes yes yes yes Knee a l i g n m e n t valgus valgus valgus r e c u r - varus varus valgus varus vatum valgus Q-angle 15° 20° 18° 20° 17° 20° 19° 20° Rearfoot varus alignment 3° 8° 8° 10° 6° 4° 5° 10° Forefoot varus alignment 10° 6° 10° 6° 4° 4° 4° 2° Overpronation yes yes yes yes yes yes yes yes Leg-length equal equal L<R 1 equal equal L<R 1 equal equal cm * cm* Peak t o r q u e (N.m) Quadriceps - concentric 87 128 76 78 90 114 121 67 144 84 80 110 168 164 132 - eccentric 233 Hamstrings 107 89 66 122 96 85 73 - concentric 111 158 - eccentric 138 120 91 66 121 105 92 Hamstrings/Quadriceps r a t i o .87 1.17 .85 1.36 .70 1.09 - concentric 1.23 .84 .95 1.43 1.14 .60 .94 .52 .64 .70 - eccentric Age ( y e a r s ) H e i g h t (cm) Weight (kg) Km/week r u n n i n g Pain - location  *  l e f t l e g s h o r t e r t h a n r i g h t by one c e n t i m e t e r  - 56 -  Certain researchers  (Winter,  a v e r a g i n g t h e EMG p a t t e r n s o f individual  differences  subjects with a c l i n i c a l  o f each p a t i e n t .  order to evaluate c l i n i c a l group,  1 9 8 4 , R i c h a r d s e t a l . 1985) b e l i e v e  differences  i t m u s t be done on an i n d i v i d u a l  patients  as a g r o u p .  use t h i s  t e c h n i q u e a l a r g e d a t a bank o f  is  required plus  subject  Winter  It  is  their  p r o b l e m masks  suggestion that  between p a t i e n t s and a  out,  normal  however, subjects'  improved n o r m a l i z a t i o n techniques  the in  control  b a s i s a n d n o t by c o m p a r i n g  (1984) p o i n t s  that  the  that in order muscle  to  activity  t o reduce the between  -  variability.  In t h i s  study the i n d i v i d u a l  subjects with patellofemoral control  group,  muscle a c t i v a t i o n p a t t e r n s of  those  p a i n s y n d r o m e h a v e been c o m p a r e d t o  h o w e v e r t h e r e s u l t s m u s t be v i e w e d c a u t i o u s l y  for  the different  reasons. The s m a l l possibility Table VII  number o f  of  subjects  i n the control  (n=12) h a s  i n c r e a s i n g the v a r i a b i l i t y of the r e s u l t s .  t h e mean EMG p a t t e r n s o f  not always f a l l  within  a normal  (Gaussian)  the  As seen  the subjects i n the control  comparison t o what i s c o n s i d e r e d a ' n o r m a l ' as  group  in  group  did  d i s t r i b u t i o n , w h i c h makes a group  (the control  group)  not  significant. It  is  also important to point out that t h i s  and a t t e m p t e d t o r e l a t e t h e a l i g n m e n t f e a t u r e s , clinical femoral  s t u d y has o n l y  addressed  s t r e n g t h measurements,  s i g n s a n d symptoms a n d t h e EMG r e s u l t s o f e a c h s u b j e c t . p a i n syndrome i s  variation in its  features  a complicated c l i n i c a l  entity with  from p a t i e n t to p a t i e n t ,  certain other contributing factors  Patello-  considerable  a n d t h e r e may h a v e  t h a t were not a s s s e s s e d o r  been  discussed.  -  57 -  These i n c l u d e t r a i n i n g e r r o r s , w h i c h a c c o r d i n g t o James e t a l . a c c o u n t f o r 60% o f  the lower extremity i n j u r i e s to runners.  category of  t r a i n i n g e r r o r s t h e r e are such f a c t o r s  the type of  running surface,  intense workout,  (1978)  Within  the  as e x c e s s i v e m i l e a g e ,  a r a p i d change i n r u n n i n g r o u t i n e o r a  a n y one o f w h i c h may p r o v o k e p a t e l l o f e m o r a l  sudden  pain.  A n o t h e r i m p o r t a n t a s p e c t i n the o c c u r r e n c e o f knee i n j u r i e s as a r e s u l t running i s who i s  footwear.  A r u n n e r who h a s e x c e s s i v e p r o n a t i o n o f  not wearing a w e l l  extent that w i l l 1978).  indicate  s u p p o r t i n g shoe w i l l  deform t h e shoe t o  the adverse s t r e s s e s at the f o o t  These s t r e s s e s are o f t e n  r e f l e c t e d up t o t h e  There are other p o s s i b l e c l i n i c a l  of  Aside  from a t i g h t l a t e r a l  to the medial  soft tissues  r e s e m b l e PFPS u n t i l  such as O s g o o d - S c h l a t t e r ' s tendon b u r s i t i s ,  make i n f e r e n c e s results,  tendinitis,  of  & Hungerford,  group.  number o f  would  examined,  infrapatellar fat  pad  1977). results  it  is  f r o m t h e d a t a t h a t has been c o l l e c t e d ,  that  stress  recurrent  generalized synovitis,  t h e m u s c l e s t r e n g t h v a l u e s and t h e c l i n i c a l  variability  loading  patellae  t h e k n e e h a s b e e n more t h o r o u g h l y  i n a n a l y z i n g the i n d i v i d u a l  k e e p i n g i n mind the small  o r abnormal  pain  t h e p a t e l l a and o t h e r c o n d i t i o n s w h i c h  pes a n s e r i n e b u r s i t i s ,  syndrome (James, 1979, F i c a t Therefore,  joint  investigation),  syndrome, q u a d r i c e p s  al.  for  abnormal  t h e r e may be t r u e c h o n d r o m a l a c i a  subluxation or d i s l o c a t i o n of at f i r s t  (James e t  reasons  retinaculum, p l i c a ,  ( w h i c h w o u l d be d e t e r m i n e d by a r t h r o s c o p i c  an  from p a t e l l o f e m o r a l  the a r t i c u l a r c a r t i l a g e of the patellofemoral  and  knee.  and/or anatomical  a n t e r i o r k n e e p a i n , w h i c h m u s t be d i f f e r e n t i a t e d syndrome.  the foot  of  subjects  only possible  to  a n d w h e r e t h e EMG  features  in the control  agree,  group and  the  -  58  -  a.6 _  0  10  28  30  40  50  60  70  % CYCLE  80  90  100  Figure 16  Subject SC.  The e n s e m b l e a v e r a g e s (VM), this  rectus  femoris  (crossed line) (RF)  the vastus  and t h e v a s t u s l a t e r a l i s  medialis (VL)  s u b j e c t a r e c o m p a r e d t o t h e mean m u s c l e p a t t e r n s o f  control  group  line).  Heel-strike is  while  of  toe-off  (solid line)  is  + one s t a n d a r d d e v i a t i o n  a t 0 a n d 100%  i n d i c a t e d by  *  .  of  the g a i t  of the  (dotted  cycle,  -  A s c a n be s e e n i n F i g u r e  59  16, the a c t i v i t y l e v e l  q u a d r i c e p s m u s c l e s f o r S u b j e c t SC i s control  group,  point  the c o n t r o l  knee f l e x i o n  the quadriceps  (Winter,  1983).  This  subject's  concentrically was 1 . 2 3  concentrically  (Table  range  (.43  -  .90)  vastus l a t e r a l i s ,  able  in  ratio  thought to  indicated a notable  indicates and  of  (H/Q that  nearly  i s outside of  difference  As t h e q u a d r i c e p s work (Winter,  the vastus medial i s  pull  were  ratio  the  1983)  first  and  the vastus  their  eccentrically  i t may be t h a t  during the running the quadriceps  lateralis.  the  between  the cycle  from  c a s e i t may be t h a t t h e v a s t u s m e d i a l i s was  to balance the l a t e r a l  be  and  the vastus medial i s  i n t h e r e d u c e d peak t o r q u e v a l u e s o f In t h i s  the  (1982).  EMG p a t t e r n s o f  the r e s u l t s  l o w e r peak EMG a m p l i t u d e o f  strength test.  control  Her h a m s t r i n g s / q u a d r i c e p s  The c o n c e n t r i c  r e p o r t e d by N o s s e  of  1979).  and .95 e c c e n t r i c a l l y w h i c h  levels during stance.  reflected  is  group both e c c e n t r i c a l l y  IV, Table X I ) .  subject's  At  revealed t h a t her r i g h t quadriceps  d u r i n g s t a n c e and then c o n c e n t r i c a l l y  is  to  her h a m s t r i n g s were s t r o n g e r than her q u a d r i c e p s  Comparing t h i s  activity  stance.  are working e c c e n t r i c a l l y  the c o n t r o l  t h e same s t r e n g t h e c c e n t r i c a l l y .  one  f l e x i n g to absorb the f o r c e s  ( E l l i o t t and B l a n k s b y ,  concentrically  the  the  i s outside of  T h e r e was a l s o l e s s EMG a c t i v i t y  strength tests  w e a k e r t h a n t h e mean o f  three of  t h a n t h e a v e r a g e EMG o f  f e m o r i s o f S u b j e c t SC d u r i n g s w i n g p h a s e , when i t  w o r k i n g as a h i p f l e x o r  ratio)  all  g r o u p ' s mean d u r i n g e a r l y  i n t h e g a i t c y c l e the knee i s  foot contact while  rectus  less  of  and i n p a r t i c u l a r t h e v a s t u s m e d i a l i s  standard deviation of this  -  the  not  - 60 -  T h i s s u b j e c t h a d genu v a l g u m a n d a Q - a n g l e o f LeVeau & B e r n h a r d t patella. moderate  (1984) enhances t h e tendency t o l a t e r a l  Her r e a r f o o t (Taunton,  and f o r e f o o t  was p r e s e n t w i t h normal  contact of  r e s u l t of  lateral  due t o t h e m e d i a l  her foot  knee p a i n f o r  running.  (James e t a l . 1 9 7 8 ) .  i n f l a m m a t i o n and p a i n  considered  towards She h a d  k n e e p a i n may be due t o e a r l i e r  t h e odd f a c e t w i t h t h e m e d i a l  soft  the  s i x t o seven y e a r s and r e p o r t e d t h a t  Her medial  tracking of  to  t r a c k i n g of  v a r u s a l i g n m e n t w o u l d be  e t a l . 1985) and a c o n t r i b u t i n g f a c t o r  compensatory p r o n a t i o n of experienced medial  15° w h i c h a c c o r d i n g  the p a t e l l a  femoral  c o n d y l e as  ( K e s s l e r and H e r t l i n g ,  1984).  than  a  1983),  t i s s u e s b e i n g s t r e t c h e d and s t r a i n e d l e a d i n g (LeVeau, & Bernhardt,  it  to  or  - 61  -  0 . 6 ^  % CYCLE Figure 17  S u b j e c t HB.  As i n F i g u r e average of  16, the crossed l i n e  the vastus medial i s ,  vastus l a t e r a l i s  for  this  rectus  subject,  muscle a c t i v i t y of  the control  standard deviation  (dotted  represents  femoris  ensemble  and  the  c o m p a r e d t o t h e mean  group  line).  the  (solid line)  + one  - 62 -  Figure  17 showed t h a t t h e l e v e l s o f m u s c l e a c t i v i t y o f  the  three  q u a d r i c e p s m u s c l e s f r o m S u b j e c t HB w e r e l o w e r t h a n t h e means o f control  group.  The r e s u l t s a l s o r e v e a l e d t h a t a l t h o u g h t h e p h a s i n g o f  p a t t e r n s was s i m i l a r ,  t h e peak EMG a m p l i t u d e s o f  d u r i n g s t a n c e and r e c t u s f e m o r i s standard deviation of This  subject's  the control  control that,  d u r i n g swing phase were l e s s than  t h e mean o f  the control  group e x c e p t  s i m i l a r t o S u b j e c t S C , t h e r e d u c e d EMG l e v e l a s s o c i a t e d w i t h the low e c c e n t r i c  from the s t r e n g t h  The H/Q r a t i o s  from t h i s  of  the c o n t r o l  I t may be  the vastus  s u b j e c t were c o n c e n t r i c  .86 and  for  eccentric than  A l t h o u g h t h e r e h a v e b e e n no p u b l i s h e d s t u d i e s on t h e  group  in this  s t u d y was  . 7 3 (+  t h e mean H/Q  S h e h a d genu v a l g u m , a Q - a n g l e o f 20°,  knee  and  Her h i g h e r  t r a c k i n g o f t h e p a t e l l a a n d a s s u c h s h e c o u l d be e x p e r i e n c i n g h e r soft  pain  from  Q - a n g l e a n d t h e genu v a l g u m may h a v e b e e n c o n t r i b u t i n g t o  the medial  ratio  moderate r e a r f o o t  v a r u s a l i g n m e n t and c o m p e n s a t o r y o v e r p r o n a t i o n .  from o v e r s t r e t c h i n g of  knee  .253).  f o r a t l e a s t f i v e y e a r s , w h i c h was s e v e r e e n o u g h t o s t o p h e r  normal  medialis  her h a m s t r i n g s were s t r o n g e r  S u b j e c t HB r e p o r t e d t h a t s h e h a d e x p e r i e n c e d r i g h t m e d i a l  forefoot  the  peak t o r q u e v a l u e  flexor/extensor strength relationship eccentrically,  running.  for  test.  which revealed that e c c e n t r i c a l l y  the quadriceps.  for  one  g r o u p ' s mean.  g r o u p ' s mean ( 8 4 N.m c o m p a r e d t o 170 N.m + 5 0 . 3 3 ) .  the quadriceps  1.4,  the vastus medial i s  q u a d r i c e p s w h i c h was l e s s t h a n - one s t a n d a r d d e v i a t i o n o f  during stance i s  the  p e a k t o r q u e v a l u e s f r o m t h e s t r e n g t h t e s t w e r e w i t h i n +_  one s t a n d a r d d e v i a t i o n o f eccentric  the  than  lateral pain  t i s s u e s or from e a r l i e r than  normal  - 63 -  contact of Lieb  t h e o d d f a c e t on t h e m e d i a l  and P e r r y  vastus medial i s lateralis, medial i s  (1980)  and s u p e r i o r p u l l  lateral  pull  Therefore,  normal  a less  t r a c k i n g of  by t h e v a s t u s l a t e r a l i s .  alignment of  is  the  (Fox,  vastus vastus  1975).  LeVeau and  not able to  the p a t e l l a  a c t i v e vastus medial i s  the p a t e l l a  the  s t a n c e a n d may h a v e a l l o w e d  s u g g e s t t h a t a weakened v a s t u s m e d i a l i s  to l a t e r a l  of  a p p e a r s t h a t i n t h i s c a s e a n d i n S u b j e c t SC t h e  to the maintenance of groove.  the l a t e r a l  had l e s s a c t i v i t y d u r i n g e a r l y  g r e a t e r degree of  condyle.  (1971) and B a s m a j i a n (1970) have r e p o r t e d t h a t  should o f f s e t  but i t  femoral  in  i n the  a Rogers  contribute femoral  i t s e l f may  contribute  -  0  20  1  30  40  64  -  I  I  I  50  60  70  % CYCLE  T  1  80  1  90  100  Figure 18  S u b j e c t EC.  A comparison of (crossed line) group  rectus  was b e l o w t h a t o f medial i s .  patterns  +_ o n e s t a n d a r d d e v i a t i o n  for  the vastus medial i s  m u s c l e s have been p r e s e n t e d f o r  obtained for  femoris.  the control  In t h i s  t h a n - one s t a n d a r d d e v i a t i o n o f  the  lateralis control  (dotted  and the  line).  vastus  S u b j e c t E C , a s no r e c o r d i n g  case, the amplitude of  group e x c e p t a t h e e l - s t r i k e  The p e a k a m p l i t u d e o f  the vastus medial i s  and t h e v a s t u s  t o t h e mean m u s c l e a c t i v i t y o f  (solid line)  Only the a c t i v i t y lateralis  the vastus medial i s  the vastus l a t e r a l i s the control  and t h e v a s t u s l a t e r a l i s  in  both  for  the  was  muscles vastus  s t a n c e was  less  g r o u p ' s mean.  In f a c t  both  had n e a r l y t h e  same p e a k  - 65 -  amplitude during stance f o r t h i s  subject,  t h e v a s t u s m e d i a l i s was s l i g h t l y  greater.  All  of  a l t h o u g h t h e peak a m p l i t u d e  t h e peak t o r q u e v a l u e s f r o m t h e s t r e n g t h t e s t f o r S u b j e c t EC  were l o w e r than t h e c o n t r o l concentrically  a n d 1.14  group's  averages.  eccentrically  H e r H/Q r a t i o s w e r e  stronger.  concentrically  The l i t e r a t u r e on H/Q r a t i o s  the r a t i o v a r i e s from  1.17  i n d i c a t i n g that the hamstrings  q u a d r i c e p s w e r e n e a r l y t h e same s t r e n g t h a l t h o u g h t h e h a m s t r i n g s slightly  of  .43 -  suggests  and  were  that  . 9 0 , d e p e n d i n g upon t h e  angular  velocity. S u b j e c t EC was r u n n i n g an a v e r a g e o f 4 0 k m / w e e k . t h r e e months p r i o r Q - a n g l e o f 20°,  her r e a r f o o t  a l i g n m e n t was 10°, 1.2  to the diagnosis  subject's  t r a c k i n g of however,  v a r u s a l i g n m e n t was 8° a n d f o r e f o o t  Rather than e x p e r i e n c i n g medial  she r e p o r t e d l a t e r a l  and i n f r a p a t e l l a r p a i n .  is  1977).  However,  f o r excessive tightening of  not p o s s i b l e Some a u t h o r s  to completely  was  (Mariani  Some o f  this  the l a t e r a l  and C a r u s o ,  the vastus medial i s ,  through  1979; Fox,  syndromes i s  pain  the  retinaculum  the s u b j e c t s were not the l a t e r a l  lateral  pain  soft  substantiate the l o c a t i o n  q u a d r i c e p s weakness i n p a t e l l a r weakness o f  leg  knee  compression forces  due t o e x c e s s i v e t i g h t e n i n g o f  ( F i c a t and H u n g e r f o r d , particularly  varus  a l i g n m e n t m e a s u r e s may h a v e p r e d i s p o s e d h e r t o  the p a t e l l a .  facet  Her l e f t  a  right.  c o u l d be r e l a t e d t o h i g h e r t h a n n o r m a l lateral  pain  She h a d genu v a l g u m w i t h  and she had compensatory p r o n a t i o n .  cm s h o r t e r t h a n t h e This  of PFPS.  She n o t e d k n e e  examined  tissues,  of her  so  pain.  1975) have b e l i e v e d  attributable  h o w e v e r t h e EMG r e s u l t s  it  solely  that  to  from t h i s  subject  - 66 -  s u g g e s t h e r a c t i v i t y l e v e l s a r e n e a r l y t h e same b e t w e e n t h e medial i s  and v a s t u s l a t e r a l i s .  Indeed i t  is  a reduced a m p l i t u d e compared t o t h e c o n t r o l to her decreased quadriceps ( M a c l n t y r e and R o b e r t s o n ,  strength.  in press)  the vastus l a t e r a l i s  the control  group i n t h i s  that  g r o u p a n d w h i c h may be  The r e s u l t s o f  a pilot  study.  has  related  study  showed t h a t t h e v a s t u s l a t e r a l i s  peak a m p l i t u d e i n s t a n c e h i g h e r t h a n t h e v a s t u s m e d i a l i s , r e s u l t s of  vastus  similar to  had a the  - 67 -  0.6_  % CYCLE  Figure 19  S u b j e c t TR.  A comparison of medial i s ,  rectus  the ensemble averages o f  lateralis  of  time the a c t i v i t y  the control  a b s o r p t i o n phase of  early  to  the  group.  S u b j e c t TR s h o w e d r e d u c e d a c t i v i t y  d u r i n g the shock  vastus  f e m o r i s and t h e v a s t u s l a t e r a l i s  average muscle patterns of  The EMG r e c o r d s  the  i n the  stance.  i n t h e v a s t u s m e d i a l i s was g r e a t e r t h a n t h e  vastus  At the control  same  - 68 -  g r o u p ' s mean a c t i v i t y t h r o u g h o u t t h e g a i t c y c l e . amplitude of lateralis  for  t h e v a s t u s m e d i a l i s was g r e a t e r t h a n t h a t o f this  subject.  Rectus  a n d may i n d i c a t e t h a t  quadriceps  it  is  the  t h a n one s t a n d a r d d e v i a t i o n o f were c o n c e n t r i c  all  swing compared t o the  control  c o n t r i b u t i n g more t h a n u s u a l  of Subject TR's  the control  .85 and e c c e n t r i c  T h i s s u b j e c t had c o m p l a i n e d o f  to  s t r e n g t h t e s t s were  g r o u p ' s mean.  H e r H/Q  plus  r i g h t medial  recurvatum, with a Q-angle of  18°.  a l i g n m e n t may h a v e b e e n c o n t r i b u t i n g t o l a t e r a l  S h e h a d genu  She o v e r p r o n a t e d and had her r i g h t  t r a c k i n g of  foot.  the  i n t h i s c a s e t h e v a s t u s m e d i a l i s was more a c t i v e d u r i n g lateralis.  ratios  k n e e p a i n f o r two y e a r s .  w h a t i s c o n s i d e r e d t o be m o d e r a t e v a r u s a l i g n m e n t o f  that the vastus  less  .6.  She r e p o r t e d t h a t t h e p a i n had c a u s e d h e r t o s t o p r u n n i n g .  however,  vastus  activity.  The p e a k t o r q u e v a l u e s o f  valgum,  peak  f e m o r i s a l s o h a d i n c r e a s e d EMG  a m p l i t u d e from s t a n c e phase i n t o e a r l y group,  In f a c t t h e  Her  patella, stance  - 69 0 . 6 ^  0  1 0  20  30  40 %  50 60 CYCLE  Figure  S u b j e c t RW  Ensemble averages o f medial i s ,  rectus  to the control  of  the control  v a s t u s l a t e r a l i s was l e s s  80  90  1 00  20  the three quadriceps  -  the  vastus  f e m o r i s and the v a s t u s l a t e r a l i s  compared  group.  A s c a n be s e e n i n F i g u r e 20, the patterns  70  t h e EMG p a t t e r n s  group.  However,  of  S u b j e c t RW  followed  t h e peak a m p l i t u d e o f  t h a n one s t a n d a r d d e v i a t i o n o f  the  the  control  - 70 -  g r o u p ' s mean i n s t a n c e a n d r e c t u s  f e m o r i s was j u s t l e s s t h a n -  standard deviation of the control  g r o u p ' s mean d u r i n g s t a n c e a n d s w i n g .  The s t r e n g t h t e s t s r e v e a l e d o n l y be w e a k e r t h a n t h e c o n t r o l concentric  1.36  difference This  peak  malalignment features and l a t e r a l  accompany f e m o r a l  s h e was r u n n i n g .  and m i l d v a r u s a l i g n m e n t o f James  the p a t e l l a .  'miserable malalignment'  mean a c t i v i t y .  foot,  the p a t i e n t e x t e r n a l l y  the Q-angle.  Although  of Q-angle  rectus  t h e EMG r e c o r d s  femoris  is  less  the  rotates  anteversion/ description  of  patient. suggest that the  not as a c t i v e as t h e v a s t u s medial i s  case that  her r i g h t  He h a s f o u n d t h a t genu v a r u m may  may a p p l y t o t h i s  A s i n S u b j e c t s EC a n d T R ,  two  She h a d genu  t o an i n c r e a s e d  r e t r o v e r s i o n a t t h e h i p has n o t been e v a l u a t e d , James'  in this  little  n e c k a n t e v e r s i o n , a n d t h a t i n an a t t e m p t t o p l a c e  the t i b i a which then increases  is  were  (1979) has r e p o r t e d a sequence  f o o t s t r a i g h t ahead r a t h e r than i n - t o e i n g ,  lateralis  were  a n d t h a t t h e r e was  t h a t he b e l i e v e s c o n t r i b u t e s  tracking of  ratios  and r e t r o p a t e l l a r p a i n f o r  The p a i n was p r e s e n t w h i l e  w i t h compensatory p r o n a t i o n .  to  torques.  s u b j e c t had s u f f e r e d from m e d i a l  v a r u m w i t h a Q - a n g l e o f 20°  H e r H/Q  torque  .9 i n d i c a t i n g t h a t h e r h a m s t r i n g s  than her quadriceps  in their eccentric  to three y e a r s .  quadriceps  g r o u p ' s mean peak t o r q u e s .  and e c c e n t r i c  stronger concentrically  the concentric  one  vastus  during stance phase,  a c t i v e than the c o n t r o l  and  group's  -  40  71  -  50 60 CYCLE  %  ! 00  Figure 21  Subject SS.  The EMG p r o f i l e s  of  the vastus l a t e r a l i s averages of  the vastus medial i s ,  s u p e r i m p o s e d on t h e g r a n d  the c o n t r o l  The m u s c l e a c t i v a t i o n p a t t e r n s o f control  group's  average p a t t e r n .  femoris ensemble  S u b j e c t SS w e r e a l l  lower than  The v a s t u s l a t e r a l i s was l e s s  the control  and  group.  s t a n d a r d d e v i a t i o n d u r i n g s t a n c e and r e c t u s one s t a n d a r d d e v i a t i o n o f  rectus  than -  f e m o r i s was a l s o l o w e r  g r o u p ' s mean i n  swing  the  phase.  than  one  -  N o t o n l y was t h e a m p l i t u d e l e s s , d e v i a t e d from i t s  usual  curve during  in press)  activity  for this  .84 c o n c e n t r i c a l l y  the absence of the  s u b j e c t were a l l  second  the control  t o r q u e w h i c h was  g r o u p ' s mean.  i n d i c a t i n g that her  quadriceps  six years.  and  S h e h a d genu v a r u m , w i t h a Q - a n g l e  l e g was one c e n t i m e t e r s h o r t e r t h a n t h e r i g h t .  and f o r e f o o t  were  hamstrings.  r e t r o p a t e l l a r pain for and h e r l e f t  of above  H e r H/Q r a t i o s  S u b j e c t SS r e p o r t e d t h a t s h e h a d s u f f e r e d f r o m m e d i a l  of  Her  v a r u s a l i g n m e n t was c o n s i d e r e d m o d e r a t e ,  c o n t r i b u t i n g to overpronation of subject's  1979;  near to the average  quadriceps  and .52 e c c e n t r i c a l l y ,  were s t r o n g e r than t h e  rearfoot  also  ( E l l i o t t and B l a n k s b y ,  because of  group, except f o r e c c e n t r i c  one s t a n d a r d d e v i a t i o n o f  17°  femoris  swing.  The s t r e n g t h t e s t s the control  but i n t h i s case rectus  pattern of  M a c l n t y r e and R o b e r t s o n ,  72 -  a l i g n m e n t may f i t  her f o o t .  James'(  Similar  t o S u b j e c t RW,  1979) d e s c r i p t i o n o f  m a l a l i g n m e n t ' , w h i c h may h a v e c o n t r i b u t e d t o l a t e r a l  this  'miserable  t r a c k i n g of  the  patella. Even though t h i s group's less  subject's  average or above,  s t r e n g t h t e s t s were near t o t h e  i t would appear t h a t the vastus l a t e r a l i s  a c t i v e d u r i n g the s t a n c e phase o f  d i d n o t show t h e s e c o n d b u r s t o f  running.  activity  in  Similarly,  swing phase.  results  i n d i c a t e t h e v a l u e o f d e t e r m i n i n g a n EMG p e r c e n t  value.  Richards et a l .  (1985) have d e s c r i b e d t h i s  amplitude during gait/peak contraction  x 100%.  control  This  femoris  subject's  utilization  v a l u e a s t h e p e a k EMG  EMG a m p l i t u d e d u r i n g a m a x i m a l  Although t h i s  rectus  was  voluntary  study d i d not lend i t s e l f  to  obtaining  - 73 -  this  v a l u e due t o t h e l o g i s t i c s  a useful  i n d i c a t o r of  of equipment l o c a t i o n ,  the percent of  a c t i v a t i o n of  Four out of e i g h t of the experimental the vastus l a t e r a l i s  less  the subjects  deviation  (Table V I I ) .  t h i s may i n d i c a t e  i n the control  running, while  further  o n l y two o u t  study to determine i f  amplitudes of  the vastus l a t e r a l i s during stance,  if  of  standard small  s u b j e c t numbers  analysis with a t - t e s t  difference  be  peak were  indicated  t h e v a s t u s l a t e r a l i s had been t h e o n l y m u s c l e t e s t e d t h e r e w o u l d  been a s i g n i f i c a n t  from  there would  b e t w e e n t h e g r o u p s when c o m p a r i n g t h e  Furthermore, a s t a t i s t i c a l  gait.  control  group were l e s s t h a n - one  difference  if  the  A l t h o u g h t h e p r e s e n t s u b j e c t numbers w e r e  a need f o r  been  s u b j e c t s h a d EMG a m p l i t u d e s  a significant  greater.  a muscle during  t h a n - one s t a n d a r d d e v i a t i o n o f  g r o u p ' s mean d u r i n g t h e s t a n c e p h a s e o f eleven of  i t w o u l d have  that  have  b e t w e e n t h e g r o u p s when c o m p a r i n g t h e  peak  EMG a m p l i t u d e s . However,  the c l i n i c a l  reduced vastus l a t e r a l i s explain in relation medial  i n f o r m a t i o n f o r each o f  the four  subjects with  EMG a m p l i t u d e was i n c o n s i s t e n t a n d d i f f i c u l t  to the muscle a c t i v i t y .  k n e e p a i n , w h i l e one h a d l a t e r a l  Three of  knee p a i n .  the subjects  (1979) have s u g g e s t e d , i t  is  p o s s i b l e t o have l a t e r a l  the p a t e l l a as a r e s u l t o f each t y p e o f h a s on o t h e r a s p e c t s o f Additionally,  the lower  had  (1984)  tracking  and  of  knee a l i g n m e n t and t h e e f f e c t s  it  extremity.  t h e m u s c l e s t r e n g t h r e s u l t s v a r i e d f r o m one s u b j e c t  values near to the control  to  Two s u b j e c t s h a d genu  v a l g u m a n d two h a d genu v a r u m , a l t h o u g h a s L e V e a u a n d B e r n h a r d t James  a  g r o u p ' s mean e x c e p t f o r e c c e n t r i c  with  quadriceps  w h i c h was a b o v e one s t a n d a r d d e v i a t i o n , t o o n e s u b j e c t who h a d v a l u e s  all  - 74 -  less  t h a n - one s t a n d a r d d e v i a t i o n o f  the control  g r o u p ' s mean.  In d i s c u s s i n g q u a d r i c e p s weakness, t h e l i t e r a t u r e has emphasized the vastus medial i s  is  the muscle t h a t i s most o f t e n weaker  1968, Fox 1975, M a r i a n i  & C a r u s o , 1979, LeVeau & R o g e r s ,  would appear from the r e s u l t s of l a t e r a l i s may a l s o o c c u r warranted.  this  (Hughston,  1980) b u t  study t h a t weakness o f  that  the  i n PFPS and f u r t h e r i n v e s t i g a t i o n w o u l d  it  vastus be  - 75 0 .6  _  0  1 0  20  30  40 %  50 60 CYCLE  70  80  90  100  Figure 22  Subject JH.  A comparison of vastus medial i s ,  this  rectus  the average patterns  The EMG p r o f i l e s this  for  subject's  of  ensemble averages of  f e m o r i s and t h e v a s t u s l a t e r a l i s the control  the vastus l a t e r a l i s  t h e peak a m p l i t u d e s w e r e s l i g h t l y  to  group.  and t h e v a s t u s m e d i a l i s  s u b j e c t had a s i m i l a r p a t t e r n t o t h e c o n t r o l  although  the  group's  average  l a t e r and l o w e r d u r i n g  from  pattern, stance  -  than the c o n t r o l  group.  76 -  The p e a k a m p l i t u d e f o r  rectus  s t a n c e was a b o v e one s t a n d a r d d e v i a t i o n o f  the control  d u r i n g s w i n g p h a s e t h e r e was an a b s e n c e o f  the second  This subject's  s t r e n g t h v a l u e s were a l l  a v e r a g e s a n d h e r H/Q r a t i o s w e r e c o n c e n t r i c She r e p o r t e d i n f r a p a t e l l a r p a i n o f experienced the pain w h i l e 20°,  running,  femoris  during  g r o u p ' s mean,  but  curve.  near to the c o n t r o l .7 a n d e c c e n t r i c  group's  .64.  two y e a r s d u r a t i o n a n d a l t h o u g h  she had n o t s t o p p e d .  she  H e r Q - a n g l e was  s h e h a d genu v a r u m , m i l d v a r u s a l i g n m e n t a t h e r f o o t a n d  compensatory  pronation. F r o m t h e EMG r e c o r d s ,  t h e r e a p p e a r e d t o be l e s s  f e m o r i s d u r i n g swing phase f o r t h i s  subject,  activity  during stance phase.  activity  l e v e l s were near t o the c o n t r o l  Five out of  seven of  group's  subjects  Although t h i s flexor  rectus fell  but a greater l e v e l  the experimental  group's  the control  g r o u p ' s mean d u r i n g  o f - one s t a n d a r d d e v i a t i o n  d u r i n g the swing phase o f project to  h a d an EMG a m p l i t u d e  eleven of  s t u d y has not c o n s i d e r e d t h e r o l e o f  be a w o r t h w h i l e  of  mean.  subjects  f e m o r i s , w h i l e two o u t o f outside  rectus  O t h e r w i s e h e r m u s c l e s t r e n g t h a n d EMG  l e s s t h a n - one s t a n d a r d d e v i a t i o n o f swing phase o f  recruitment of  rectus  the  control  (Table  VII).  f e m o r i s as a  running i t would appear t h a t t h i s  pursue.  the  hip  would  - 77 -  0 .6 _  %  CYCLE  Figure 23  Subject JG.  The e n s e m b l e a v e r a g e s o f  the vastus medial i s ,  and t h e v a s t u s l a t e r a l i s  compared t o t h e c o n t r o l  average muscle  This  subject's  but were s l i g h t l y stance.  In t h i s  followed  in amplitude,  the p r o f i l e s  except for  c a s e t h e peak a m p l i t u d e o f  standard deviation of  femoris  group's  activity.  EMG p a t t e r n s lower  rectus  the control  group's  rectus  rectus  mean.  of  the c o n t r o l femoris  group  during  f e m o r i s was a b o v e  one  - 78 -  Her muscle s t r e n g t h v a l u e s were a l l means a n d i n f a c t , of  the concentric  - one s t a n d a r d d e v i a t i o n .  eccentric  .70 w h i c h  less  quadriceps  than the c o n t r o l  group's  and h a m s t r i n g s were  H e r H/Q r a t i o s w e r e c o n c e n t r i c  i n d i c a t e d that her concentric  quadriceps  1.09  She h a d n o t e d m e d i a l Q - a n g l e was 19°, compensatory  testing  hamstrings.  and r e t r o p a t e l l a r p a i n f o r  s i x months.  w i t h genu v a l g u m , m i l d v a r u s a l i g n m e n t o f  Her  her f o o t  and  pronation.  A s i n S u b j e c t SS t h e a p p a r e n t i n c o n g r u e n c y d e c r e a s e d s t r e n g t h v a l u e s b u t EMG p a t t e r n s  between t h i s  subject's  s i m i l a r to the control  a v e r a g e p a t t e r n s may h a v e b e e n e x p l a i n e d by a p e r c e n t EMG value.  and  and  h a m s t r i n g s w e r e n e a r l y t h e same s t r e n g t h , w h i l e d u r i n g e c c e n t r i c her q u a d r i c e p s were s t r o n g e r than t h e  outside  utilization  I t may be t h a t a l t h o u g h h e r m u s c l e s a r e w e a k e r s h e was  at a high percentage during  running.  group's  recruiting  - 79 -  Conclusion Although the r e s u l t s of  t h e g r o u p EMG p a t t e r n s  was no s t a t i s t i c a l l y s i g n i f i c a n t analyzing individual a rehabilitation normal  difference  b e t w e e n t h e two  program f o r  the runner.  If  strengthening,  of  The r e s u l t s o f  t h a t d e v i a t e d from t h e normal  this  s t i m u l a t i o n and g a i t  with  distribution to  training.  s t u d y s u g g e s t t h a t t h e r e may n o t be a  p a t t e r n o f m u s c l e a c t i v i t y t h a t i s common t o a l l of  of  functional  a muscle r e - e d u c a t i o n program i n r e g a r d  electrical  directing  a patient  c o n d i t i o n c o u l d be a n a l y z e d d u r i n g  a n d t h o s e EMG p a t t e r n s  c o u l d be t h e f o c u s  in  t h e r e was a l a r g e bank  data w i t h which to compare, the muscle a c t i v i t y of  activity  there  groups,  EMG p a t t e r n s c o u l d p r o v e t o be v a l u a b l e  P F P S o r any o t h e r c l i n i c a l  lack  indicated that  particular  p a t i e n t s w i t h PFPS.  a common f i n d i n g may be due t o t h e many p o s s i b l e  interactions  malalignment features  and e t i o l o g y  individual.  t h e f i n d i n g s m u s t be c o n s i d e r e d c a u t i o u s l y due  the small This  However,  number o f  subjects  limitations  in this  is  and a b s o r b i n g the f o r c e s  1983),  a c t i v i t y of  of  the experimental  to  some  flexing during early  to control  and B l a n k s b y  knee f l e x i o n  (1979) t h e r e i s  the hamstrings group.  a l s o knee f l e x o r a c t i v i t y .  each  a n d EMG a c t i v i t y  the f o o t h i t t i n g the ground, not only  but according to E l l i o t t  is  As t h e knee i s  the quadriceps  simultaneous contraction of there  features  necessary to recognize t h a t there are  analysis.  in  of  study.  s t u d y has a t t e m p t e d t o compare c l i n i c a l  during running but i t  eccentric  t h a t t h e c l i n i c i a n may f i n d  in this  This  stance is  there  (Winter, a  During swing  phase  Considering that f i v e out of eight  s u b j e c t s h a d H/Q r a t i o s  g r e a t e r than one,  indicating  of  that  - 80 -  t h e h a m s t r i n g s were s t r o n g e r than t h e q u a d r i c e p s , benefit  to study the a c t i v i t y of  electromyographically during Additionally, experimental control  i t w o u l d have been  both the quadriceps  and t h e  hamstrings  running.  a comparison of  the muscle a c t i v i t y p a t t e r n s of  the  g r o u p r e v e a l e d t h a t t h e r e was more o r l e s s a c t i v i t y t h a n  g r o u p ' s mean EMG p r o f i l e ,  but t h i s  or  As s u g g e s t e d  t h e d i s c u s s i o n , a p e r c e n t EMG u t i l i z a t i o n v a l u e , w h i c h R i c h a r d s e t  in  al.  h a v e d e s c r i b e d a n d u s e d may h a v e a l l o w e d a n e x p l a n a t i o n a s t o why  some s u b j e c t s h a d n o r m a l m u s c l e s t r e n g t h d u r i n g t e s t i n g b u t muscle a c t i v i t y  functionally  and c o n v e r s e l y ,  decreased  decreased muscle strength  EMG a c t i v i t y d u r i n g r u n n i n g w h i c h c l o s e l y a p p r o x i m a t e d t h a t o f group. profiles  clinical  the  I t w o u l d a l s o add i n f o r m a t i o n i n r e l a t i n g t h e i n d i v i d u a l to the control  these l i m i t a t i o n s , each attempt t o  features with functional  the understanding of  but  control  EMG  g r o u p ' s mean EMG p a t t e r n .  A l t h o u g h we r e c o g n i z e  study.  the  d i d not i n d i c a t e what degree  p e r c e n t o f m u s c l e a c t i v i t y was i n v o l v e d f o r e a c h s u b j e c t .  (1985)  of  this  relate  m u s c l e a c t i v i t y makes a c o n t r i b u t i o n  relationship  and p r o v i d e s a b a s i s f o r t h e  to  next  - 81 -  APPENDIX 4  REVIEW OF THE LITERATURE  OVERVIEW OF THE CHAPTER  The f i r s t  part of this  chapter e n t a i l s  patellofemoral  p a i n syndrome.  patellofemoral  joint  clinical  features  patellofemoral  a r e v i e w o f t h e l i t e r a t u r e on  The anatomy a n d b i o m e c h a n i c s o f t h e  are addressed before  the discussion regarding the  a n d t h e more c o m p l e x i s s u e o f t h e e t i o l o g y  of  pain.  The s e c o n d a n d t h i r d m a j o r p a r t s o f t h e l i t e r a t u r e a n a l y s i s o f muscle a c t i v i t y a t t h e knee d u r i n g r u n n i n g . electromyography,  review concern the A discussion of  i n p a r t i c u l a r r e p o r t s o f s t u d i e s on t h e knee m u s c l e s  during running, leads  into  of  a review o f the l i t e r a t u r e concerning the r e l a t i v e l y  running.  Finally,  a review o f other types o f kinematic  new c o n c e p t o f i s o k i n e t i c m u s c l e a c t i v i t y a n d s t r e n g t h t e s t i n g presented.  analyses  is  - 82 -  PATELLOFEMORAL PAIN SYNDROME  Introduction A c c o r d i n g t o Malek  and Mangine  (1981),  d e g e n e r a t i v e changes o f t h e p a t e l l o f e m o r a l 1900's.  the f i r s t  description of  j o i n t was r e p o r t e d i n t h e e a r l y  S i n c e t h e n , t h e y r e p o r t t h a t a s many a s 4 0 0 a r t i c l e s  written attempting to explain the p a t e l l a r T h e s e same a u t h o r s  Canada,  been  syndromes.  suggest that patellofemoral  p a i n syndrome (PFPS)  t h e m a j o r cause o f knee p a i n i n most s p o r t s m e d i c i n e c l i n i c s Clement e t a l . (1981),  have  i n a two y e a r r e t r o s p e c t i v e  is  i n the U.S.  survey conducted i n  f o u n d t h a t a m o n g s t t h e i r p a t i e n t s t h e k n e e w a s t h e m o s t commonly  injured site  a n d P F P S t h e m o s t common  injury.  Anatomy of the Patellofemormal J o i n t The p a t e l l a , w h i c h  i s t h e l a r g e s t s e s a m o i d bone i n t h e b o d y ,  interposed i n the quadriceps flexion  torsional  I n o r d e r t o do t h i s ,  in line  with  s t a b i l i z a t i o n of the  1979).  the t i b i o f e m o r a l  joint  include  the medial  and t h e p a t e l l a r tendon  patellofemoral  the j o i n t capsule which encloses  and t h e p a t e l l o f e m o r a l  retinacular expansions,  ligaments, lateral  should g l i d e  During  and a n g u l a r a l i g n m e n t o f t h e femur and t i b i a  The p a s s i v e s t a b i l i z e r s  lateral  1981).  i s p r o v i d e d by a c t i v e a n d p a s s i v e e l e m e n t s o f t h e e x t e n s o r  mechanism p l u s (James,  (Malek and Mangine,  and e x t e n s i o n o f t h e knee t h e p a t e l l a  the long a x i s o f the femur. patella  tendon  is  joint,  both  t h e medial and  and l a t e r a l  patellofemoral  ( F i c a t and Hungerford,  ligament i s a part of the l a t e r a l  1977).  The  retinaculum.  The  - 83 -  deep l a y e r s o f  the l a t e r a l  r e t i n a c u l u m expand i n t o  v a s t u s l a t e r a l i s m u s c l e and t h e i l i o t i b i a l (1977)  suggest t h a t the l a t e r a l  medial  r e t i n a c u l u m , and b e c a u s e i t  band and v a s t u s l a t e r a l i s , displacement of  the  it  p o s i t i o n of  retinaculum i s is  also  Ficat  stabilizes  the p a t e l l a  the p a t e l l a  r e i n f o r c e d by t h e  the p a t e l l a  r e l a t i v e to the femoral  to d i s t a l ,  from proximal  displacement of  The b o n y c o n t o u r s  the p a t e l l a  of  it  tibial  tubercle  by t h e q u a d r i c e p s  by t h e p a t e l l a r t e n d o n .  regions  - the superior,  central  vertical  ridge  inferior,  is  normally  stabilizers.  its  joint  The  and i s  s u r f a c e and i s  medial, lateral  of  the  triangular  attached  surface i s divided into  and odd f a c e t s .  and l a t e r a l  is  to  t e n d o n , and d i s t a l l y  The p o s t e r i o r  seperates the medial  pull  1977).  s u l c u s and t h e c o n f i g u r a t i o n  a n t e r i o r to the t i b i o f e m o r a l  by a r t i c u l a r c a r t i l a g e o v e r 75% o f  It  the  direction of  ( F i c a t and H u n g e r f o r d ,  the femoral  to the quadriceps  limits  adds t o t h e tendency  p a t e l l a are a l s o considered passive or s t a t i c  proximally  lateral  inferiorly,  condyles.  slightly  lies  the  iliotibial  from t h e t i b i a and e s t a b l i s h e s  t h e t i b i a b u t when i t s  shaped p a t e l l a  Hungerford  normally t h i c k e r than  a l i g n e d along the long a x i s of  lateral  the  patella.  ascent of  lateral  and  may a c c e n t u a t e t h e t e n d e n c y t o  The p a t e l l a r t e n d o n , w h i c h the proximal  tract.  the retinaculum of  regions  to  the  covered five A  (James,  1979). The i n t e r c o n d y l a r g r o o v e on t h e a n t e r i o r a s p e c t o f represents the femoral to the v e r t i c a l medial  articular  surface.  The c e n t r a l  r i d g e on t h e p a t e l l a a n d d i v i d e s  and l a t e r a l .  the d i s t a l groove  the femoral  Hyaline c a r t i l a g e covers the a r t i c u l a r  femur  corresponds surfaces  surface.  into  - 84 -  Normal  depth of  t h e i n t e r c o n d y l a r g r o o v e and h e i g h t o f  condyle b u t t r e s s the p a t e l l a against l a t e r a l The d e p t h o f of  this  femoral  the patellofemoral  (1941)  articulation  joint,  as i s  to the congruency  The p a t e l l o f e m o r a l  joint  of is  the  (Anderson, 1983).  lumbar t o the second s a c r a l aspects  important i n the the p a t e l l a .  of patellae,  lumbosacral Hertling,  congruency  contributing  s u p p l i e d by t h e p o p l i t e a l  t h a t form a c o l l a t e r a l  I n n e r v a t i o n t o t h e knee i s  segments.  artery  The a n t e r o - m e d i a l  which  circulation  from the  third  and m e d i a l supplies  when a s s e s s i n g k n e e p a i n one m u s t remember t h a t  the  the  r e g i o n o r t h e h i p may r e f e r p a i n t o t h e k n e e ( K e s s l e r &  1983).  four of  stabilizers, and m e d i a l  t h e q u a d r i c e p s m u s c l e s a r e c o n s i d e r e d t o be  with  the vastus medial i s  patellofemoral  the l a t e r a l medialis,  1979).  Wiberg  e a c h one  a r e s u p p l i e d by t h e t h i r d l u m b a r s e g m e n t , w h i c h a l s o  Therefore,  All  also  (James,  femoral  joint.  g i v e s b r a n c h e s m e d i a l l y and l a t e r a l l y a t the knee  dislocation  t h e shape o f  has d e s c r i b e d s i x c o n f i g u r a t i o n s  differently  hip.  is  the l a t e r a l  soft  tissues.  ligament, However,  r e i n f o r c i n g the medial  retinaculum  and t h e v a s t u s l a t e r a l i s  reinforcing  t h e more d i s t a l  c a l l e d vastus medialis oblique  i m p o r t a n t dynamic s t a b i l i z e r o f h a s b e e n r e p o r t e d by L i e b in p a t e l l a r alignment i s lateralis.  to o f f s e t  fibres  into  of the  femur.  displacement of  the p a t e l l a  segment o f  the  vastus  t h o u g h t t o be t h e  (Malek and M a n g i n e ,  t h e s u p e r i o r and l a t e r a l  pull  most  1981).  (1971) t h a t the major f u n c t i o n  B a s m a j i a n (1970) and James  prevents l a t e r a l  (VMO), i s  the p a t e l l a  and P e r r y  active  o f VMO  of  vastus  ( 1 9 7 9 ) h a v e s u g g e s t e d t h a t VMO  t h e p a t e l l a due t o t h e o r i e n t a t i o n o f  a t an a n g l e o f  It  a p p r o x i m a t e l y 50°  to the long  its  axis  - 85 -  Although  i t a p p e a r s t o be a s i g n i f i c a n t m u s c l e i n p a t e l l a r a l i g n m e n t a n d  in the f i n a l  d e g r e e s o f k n e e e x t e n s i o n , i t i s i m p o r t a n t t o n o t e t h a t VMO  c a n n o t work  alone  all  t o e x t e n d t h e knee ( L i e b and P e r r y ,  o f t h e q u a d r i c e p s work t o g e t h e r t h r o u g h o u t  extension  ( H a l l e n and L i n d a h l ,  The p e s a n s e r i n e m u s c l e s  the f u l l  In  range o f  knee  tibia,  and s e m i t e n d i n o s u s )  and a r e t h o u g h t t o a s s i s t i n  s t a b i l i z a t i o n t h r o u g h an i n t e r n a l  r o t a t o r y a c t i o n on t h e p r o x i m a l  (Paulos e t a l . 1980).  the biceps  rotation of the t i b i a aspect of the proximal lateral  Laterally,  f e m o r i s may a f f e c t  active  tibia  external  through the p a r t of i t s i n s e r t i o n onto the l a t e r a l tibia  (Cailliet,  i n s e r t i n g muscles c o n t r i b u t e  the p a t e l l a and t h e femoral I n summary, t h e s t a t i c  sulcus  1973).  Together  these medial  tubercle  (James,  and i t s r e l a t i o n s h i p  to  1979).  and dynamic elements o f s t a b i l i z a t i o n  t o g e t h e r f o r normal  and  t o t h e e x t e n s o r mechanism a l i g n m e n t  by c h a n g i n g t h e p o s i t i o n o f t h e t i b i a l  function  fact,  1967).  (sartorius, gracilis  i n s e r t m e d i a l l y on t h e p r o x i m a l  1971).  patellofemoral  must  mechanics.  Biomechanics of the Patellofemoral J o i n t One o f t h e m a j o r f u n c t i o n s force  of the quadriceps muscle.  of the p a t e l l a I t does t h i s  between t h e a x i s o f m o t i o n a t t h e f e m o r a l tendon,  thereby  by i n c r e a s i n g t h e d i s t a n c e  c o n d y l e and t h e q u a d r i c e p s  i n c r e a s i n g t h e e x t e n s o r moment a r m .  (1977) r e p o r t t h a t throughout t h e e n t i r e patella  i s to increase the extensor  increases  the force  on t h e amount o f k n e e  and H u n g e r f o r d  range o f motion o f t h e knee, t h e  of the quadriceps  flexion.  Ficat  by a s much a s 50%, d e p e n d i n g  - 86 -  Another major function divergent forces  of  the p a t e l l a  from the quadriceps  is  that i t  and d i s t r i b u t e s  centralizes  the  these forces  through  t h e p a t e l l a r tendon t o t h e t i b i a and t h r o u g h t h e a r t i c u l a r c a r t i l a g e the p a t e l l a to the femur. superimposed load of  Patellofemoral  a c t i v i t y plus  joint  reaction  forces, with  t h e t o r q u e g e n e r a t e d by t h e  in squatting  (James, 1979).  These high  and  loads  c o m p r e s s t h e a r t i c u l a r c a r t i l a g e b e t w e e n an a r e a o f p a t e l l o f e m o r a l w h i c h James (1979) r e p o r t s patellar  articular  of  joint  forces  is  the medial  patellae  However,  smaller or d i f f e r e n t l y  a p p r o x i m a t e l y 65%  and t h e i r j o i n t surface of  facet  of  the p a t e l l a .  the a r t i c u l a r (Ficat  the  surface  that  and H u n g e r f o r d ,  shaped, the j o i n t  t h e p o p u l a t i o n have  (James,  the  motion.  1977).  reaction  the a r t i c u l a r c a r t i l a g e of  reaction forces  contact  a r e a l s o a f f e c t e d by  The p o r t i o n o f  are increased which overloads  facet.  contact  facet  reaction forces  the p a t e l l a .  shows t h e m o s t v a r i a t i o n i s When t h i s  n e v e r more t h a n a b o u t one t h i r d o f  s u r f a c e a t any g i v e n r a n g e o f  The p a t e l l o f e m o r a l configuration  is  the  quadriceps,  c a n become a s h i g h a s t h r e e t i m e s body w e i g h t w i t h s t a i r - c l i m b i n g e i g h t t i m e s body w e i g h t  of  the  medial  normally  shaped  are normally d i s t r i b u t e d over  the  1979).  C l i n i c a l Features Patellofemoral  p a i n syndrome (PFPS)  is  d e s c r i b e d as a d i f f u s e ,  l o c a t e d pain around the p a t e l l a which a r i s e s patella  (Grana e t a l . 1984).  from abnormal  I t may be r e f e r r e d t o a s  syndrome, p a t e l l a r m a l a l i g n m e n t , p a t e l l o f e m o r a l  poorly  tracking of  peripatellar  a r t h r a l g i a , or  runner's  the  - 87  knee,  however i t  is clinically  d i f f e r e n t i a t e d from chondromalacia  in that chondromalacia implies l e s i o n s upon a r t h r o s c o p i c  -  investigation  of  the r e t r o a r t i c u l a r  ( B e n t l e y a n d Dowd,  I t has been r e p o r t e d t h a t PFPS a f f e c t s  in the l i t e r a t u r e suggest that i t (Grana e t a l . 1984), al.  and i s  relates  or along the medial directions  However,  highly  other  to sports a c t i v i t y or  e q u a l l y common among b o t h s e x e s  a dull,  reports  trauma  (Reynolds  border,  a c h i n g o n e t h a t may be b e h i n d t h e  o r w h i c h may e v e n t u a l l y r a d i a t e  (Malek and M a n g i n e ,  1981).  s i t t i n g w i t h the knees bent f o r which  et  loads  the patellofemoral  joint  present,  there i s  no h i s t o r y o f  t h e p a t i e n t may c o m p l a i n o f  activity. femoral  (movie s i g n )  during flexion  Swelling is 'locking'  a sensation of  C r e p i t i s may be p r e s e n t d u r i n g movement o f often note a s t i f f n e s s  elicit  than t h a t of  relationship  (ie. -  activity  squatting,  as seen w i t h m e n i s c a l ' g i v i n g way' the p a t e l l a  of  the  and t h e  tears,  but  knee. patient after  the p a t e l l a against  the  pain. the quadriceps  and/or  the  The s t r e n g t h o f t h e h a m s t r i n g s h a s b e e n f o u n d t o the quadriceps  i n a normal knee ( N o s s e ,  between t h e s t r e n g t h o f  r e p o r t e d by N o s s e  o r by  or t i g h t n e s s at the knee, e s p e c i a l l y  M u s c l e t e s t i n g may r e v e a l w e a k n e s s o f hamstrings groups.  all  n o t common b u t may be m i l d y  One may a l s o n o t e t h a t c o m p r e s s i o n o f  condyles w i l l  in  patella,  T h e p a i n may be a g g r a v a t e d by  long periods  ascending or descending s t a i r s ) .  less  1984).  1983). The p a i n i s o f t e n  will  cartilage  teenage f e m a l e s and  a c t i v e a t h l e t e s t h e m o s t ( B e n t l e y a n d Dowd, 1 9 8 4 ) .  patellae  1982).  The  t h e f l e x o r s t o t h e e x t e n s o r s has  ( 1 9 8 2 ) t o v a r y b e t w e e n 4 3 - 9 0 % , d e p e n d i n g upon  be  the  been  - 88 -  angular  velocity.  I t has been s u g g e s t e d t h a t t h e v a s t u s m e d i a l i s and t h e lateralis correct  s h o u l d have equal  alignment of  quadriceps weakness, Caruso  s t r e n g t h so t h a t they c o n t r i b u t e  the p a t e l l a  (Reynolds et a l . 1983).  the l i t e r a t u r e presents d i f f e r e n t  to vastus m e d i a l i s weakness.  b e l i e v e t h a t weakness o f the q u a d r i c e p s  is  pull  of  the Q-angle,  the quadriceps  which  is  i n d i c a t i v e of  lateral  tracking of  b u t by i t s e l f  the Q-angle i s  vastus  all  of  patellofemoral deformities  joint.  James  to the  the  quadriceps.  i s o f t e n a b o v e 15°  Increased i n t e r n a l  c o m p e n s a t e d f o r by e x t e r n a l  influence  (LeVeau & B e r n h a r d t ,  of PFPS.  It  is  Q-angle, will  as t h e t i b i a l  r o t a t i o n of  tubercle  or  angular the  torsional  malalignment'.  n e c k a n t e v e r s i o n ) may be the t i b i a  so t h a t the f e e t  This results  i n an  is externally rotated.  (patella alta)  are  increased  These  patients  o f t e n h a v e genu v a r u m a n d r e c u r v a t u m , s q u i n t i n g p a t e l l a e ,  riding patella  1984)  often  on t h e m e c h a n i c s o f  'miserable  (femoral  placed forward r a t h e r than i n - t o e i n g .  in  A Q - a n g l e a b o v e 15° may be  ( 1 9 7 9 ) d e s c r i b e s one g r o u p o f  hip rotation  of  the e x t e n s o r mechanism.  t h a t he h a s r e f e r r e d t o a s  and  attributable  L o w e r e x t r e m i t y a l i g n m e n t m u s t be a s s e s s e d a s t o r s i o n a l m a l a l i g n m e n t s have a s i g n i f i c a n t  Mariani  the a n g l e between t h e l i n e  not d i a g n o s t i c of  of  not s p e c i f i c  the p a t e l l a  associated with other deficiencies  In terms  (1982),  and t h e p a t e l l a r t e n d o n ,  p a t i e n t s w i t h PFPS ( S c h a m b e r g e r , 1 9 8 3 ) .  the  However, W i l d e t a l .  m e d i a l i s but r a t h e r i n d i c a t i v e of weakness o f Measurement of  to  views.  (1979) have r e p o r t e d t h a t q u a d r i c e p s weakness i s  specifically  vastus  and compensatory p r o n a t i o n o f  the  a  high foot.  - 89  Normal angulation  alignment of  t h e knee i s  (170°) a s t h e f e m u r i s  a r t i c u l a t e with the t i b i a . c o n s i d e r e d t o be a b n o r m a l respectively  (Lehmkuhl  be a s s o c i a t e d w i t h  -  c o n s i d e r e d t o be i n  slight  valgus  d i r e c t e d m e d i a l l y from the p e l v i s  to  A n g l e s much s m a l l e r o r g r e a t e r t h a n 170° a n d r e f e r r e d t o a s genu v a l g u m o r genu  and S m i t h ,  1983).  increased external  compensatory p r o n a t i o n of  the f o o t .  i n c r e a s e d by t h e e x t e r n a l  r o t a t i o n of  The p r e s e n c e o f  rotation of In t h i s  are  varum,  genu v a l g u m may  the t i b i a or  with  s i t u a t i o n , the Q-angle  the t i b i a  is  (LeVeau & B e r n h a r d t ,  1984). Another r e l a t i o n s h i p  t h a t m u s t be e v a l u a t e d i s  t h e f o o t d u r i n g w a l k i n g and r u n n i n g , and i t s patellofemoral magnitude of  joint  the forces  a n d any b i o m e c h a n i c a l (Schamberger,  in particular.  that of  affect  upon t h e k n e e a n d  As t h e s p e e d o f  gait  discrepancies  that exist will  a l s o be  phase i n r u n n i n g  flexible  r o t a t e d and t h e knee i s  and S m i t h ,  knee e x t e n d s .  1983).  If  a rapid period  As t h e f o o t i s flexing.  the  pronating,  1982)  pronation of  1983).  then there w i l l  stance  the  tibia  the t i b i a e x t e r n a l l y r o t a t e s  the f o o t and i n t e r n a l  and  rotation of  extending or i f  a  surface  is  A t a p p r o x i m a t e l y 70% o f  s t a n c e when t h e k n e e i s  of  The p r o n a t e d f o o t i s  A t t h e same t i m e , t h e k n e e f l e x i o n  the foot supinates,  are prolonged i n t o l a t e r excessive,  the  (Mann,  a b l e t o a b s o r b shock and a d a p t t o t h e ground  shock a b s o r b i n g mechanism ( W i n t e r , stance phase,  the  amplified  i t s maximum a t a p p r o x i m a t e l y 35-45% o f  (Smart e t a l . 1980).  one w h i c h i s  (Lehmukuhl  of  1983).  pronation which reaches  internally  increases  through the lower extremity increases  N o r m a l l y as the f o o t s t r i k e s the ground t h e r e i s  is  the f u n c t i o n  also  a  the the  the  tibia  they  be i n c r e a s e d s t r e s s t h r o u g h t h e f o o t a n d a n  are  - 90 -  increase  in transverse rotation  disturbance abnormal et a l .  i n the t i b i o f e m o r a l  joint  s t r e s s e s and w i l l  w h i c h m u s t be a b s o r b e d a t t h e k n e e . rotational  a l t e r the patellofemoral  cause  mechanics  (Bates  1979).  A neutral  foot is  one t h a t w i l l  l e a s t s t r a i n on t h e j o i n t s , minimal  function  ligaments,  e x e r t i o n by t h e m u s c l e s o f  position  (prone l y i n g )  the d i s t a l  the f o o t i n  (rearfoot alignment). the plane of the h e e l .  the v e r t i c a l  one t h i r d o f  the t i b i a , Forefoot  the metatarsal  stance  (James,  the heel  - heel  relationship  the h e e l / f o r e f o o t  perpendicular  rearfoot varus  Excessive or  when  axis  of  is  compensatory malalignment  varus) or malalignment  In b o t h c a s e s t h e f o o t w i l l (James e t a l .  to  neutral  to the v e r t i c a l  (1985) normal  varus 2°.  to a c h i e v e c o n t a c t w i t h the ground  1979).  a l i g n m e n t i s c o n s i d e r e d normal  (increased rearfoot  relationship.  requires  s h o u l d be p a r a l l e l  t h e f o o t i n w e i g h t - b e a r i n g o c c u r s when t h e r e i s  the leg/heel  with  nonweight-bearing  with the s u b t a l a r j o i n t  A c c o r d i n g to Taunton e t a l .  pronation of  and w h i c h  data that i n a  axis of  heads i s  c o n s i d e r e d t o be 3° a n d f o r e f o o t  the most e f f i c i e n t l y  and t e n d o n s ,  James a l s o has o b s e r v e d f r o m h i s c l i n i c a l  of  relationship will  A  of  overpronate  1978).  Etiology of Patellofemoral Pain A v a r i e t y of  factors  have been s u g g e s t e d as p o s s i b l e c a u s e s o f  femoral  p a i n ; among t h e s e a r e d e g e n e r a t i v e d i s e a s e s ,  trauma,  acute  s e v e r e trauma and m a l a l i g n m e n t o f  e x t e n s o r mechanism (Malek and M a n g i n e , s u g g e s t t h a t abnormal  1981).  the  patello-  repeated minor patellofemoral  Reider et a l .  (1981)  p a t e l l a r t r a c k i n g , secondary to malalignment of  the  - 91  q u a d r i c e p s - p a t e l l a r mechanism, i s (1979)  reports  role  of  joint  implicated etiological  (1979) b e l i e v e s  the development of  (1977) for  devoid of  factor.  is  He a l s o e m p h a s i z e s of  the  patellofemoral  that the a r t i c u l a r c a r t i l a g e of  abnormal  pain i s  pain f i b r e s  subchondral  stimuli  from the a r t i c u l a r c a r t i l a g e ,  and b l o o d v e s s e l s . diarthrodial  : the r i c h l y  Ficat  joint  and  is  a  that as  Hungerford  t h e r e a r e two  i n n e r v a t e d s y n o v i u m and  sources  the  bone.  The i n t e g r i t y o f  the a r t i c u l a r c a r t i l a g e  l u b r i c a t i o n and b i o m e c h a n i c a l cartilage  itself.  diffusion  of  function,  Articular cartilage  the deeper f i b r e s  during periods  of  is  essential  nutrition  is  joint  dependent  t o deep l a y e r s o f  non-compression.  Under  the  upon the compression  a r e l e s s p e r m e a b l e and r e s i s t t h e i n t e r s t i t i a l  Varying degrees of compression a l s o a f f e c t s the ground substance,  This i s  the  of  the  reabsorbed during periods  the basis f o r j o i n t  lubrication.  As  a d v a n c i n g c o m p r e s s i v e l o a d moves t o w a r d s n o n - c o m p r e s s e d a r e a s , pushed a l o n g the l e a d i n g edge.  flow  proteoglycan  so t h a t f l u i d e s c a p e s f r o m  a r t i c u l a r c a r t i l a g e when c o m p r e s s e d b u t i s non-compression.  to  and t o t h e n u t r i t i o n o f  the n u t r i e n t s from s u p e r f i c i a l  cartilage especially  component o f  the p a t e l l a  k n e e j o i n t m e c h a n i c s b u t he a l s o a d d s  not d i r e c t l y  s u g g e s t t h a t i n a normal  the p a i n f u l  fluid.  James  problems.  s e n s i t i v e i n d i c a t o r of  is  factor.  e x t e n s o r mechanism m a l a l i g n m e n t  the lower extremity alignment i n the e t i o l o g y  James  it  a major e t i o l o g i c a l  that in his experience,  t h e most f r e q u e n t l y  -  Decreased p e r m e a b i l i t y of  the  of  an fluid  is  articular  - 92 -  c a r t i l a g e o c c u r s under the l o a d and a l u b r i c a t i n g f i l m i s m a i n t a i n e d the s u r f a c e , w h i l e  the c a r t i l a g e  non-compressed areas Ficat  (James,  and H u n g e r f o r d  r e t u r n s t o normal  permability  patellofemoral  ( 1 9 7 7 ) h a v e shown u n d e r l o c a l  anesthetic,  p a i n , w h e r e a s p r e s s u r e on f i r m ,  was n o t d e t e c t e d by t h e p a t i e n t .  o c c u r a t deep l a y e r s a n d a f f e c t which r e s u l t s  subchondral Normal  bone,  i n the a r t i c u l a r  transmission of  Up t o 135°  of  flexion  ( F i c a t and H u n g e r f o r d ,  1977).  all  of  the  (James,  to  the  to  the medial  non-articulation  very  condyle.  nutritionally  t h e odd f a c e t  into  P o o r n u t r i t i o n may c a u s e t h e  abnormal earlier  cartilage  t o be w e a k e n e d a n d s o f t e n e d a n d a s s u c h i t w o u l d be u n a b l e t o t o l e r a t e unaccustomed  forces.  in  i n most everyday  T h i s phenomenon w o u l d become i m p o r t a n t i n t h e c a s e o f  c o n t a c t with the medial  free  late  deficient.  the p a t e l l a , which brings  odd  femoral  w h i c h may r e n d e r t h e a r t i c u l a r c a r t i l a g e  tracking of  the  facet l i e s  activities,  lateral  proximal  cartilage  (1983) p o i n t o u t t h a t t h i s  c o n t a c t makes t h e o d d f a c e t an a r e a o f  the  pain.  the medial  t h e i n t e r c o n d y l a r groove and t h e odd f a c e t c o n t a c t s K e s s l e r and H e r t l i n g  cartilage  i n the range, except f o r  By 135°  the  cartilage  p a t e l l a r c o n t a c t w i t h the femur passes from d i s t a l  a r t i c u l a t e s w i t h t h e f e m u r a t some p o i n t  condyle.  forces  and u l t i m a t e l y t o t h e development o f  as the knee f l e x e s .  facet  healthy  the energy-absorbing c a p a c i t y of  i n abnormal  that  reproduced  T h i s h a s l e d them a n d o t h e r s  1979) t o t h e h y p o t h e s i s t h a t e a r l y changes  cartilage,  in  1979).  d i r e c t p r e s s u r e on s o f t e n e d b u t i n t a c t a r t i c u l a r c a r t i l a g e patient's  on  the  - 93 -  Other causes of that  is  otherwise  a r t i c u l a r c a r t i l a g e b r e a k d o w n may i n v o l v e  h e a l t h y and w e l l - n o u r i s h e d ,  excessive patellofemoral  joint  but i s overloaded  reaction forces.  i n a p a t e l l a w i t h a s m a l l e r t h a n normal m e d i a l  small  area i s  The l a t e r a l reaction  in which  One p o s s i b l e c a u s e o f  and H u n g e r f o r d ,  1977).  increased lateral  joint  pressure  the l a t e r a l  normal of  lateral  T h e s e a u t h o r s h a v e r e p o r t e d t h a t many  p r e s s u r e syndrome.  They b e l i e v e t h a t g r e a t e r  LeVeau & B e r n h a r d t  (1984) s u g g e s t ,  connective t i s s u e s are t i g h t the medial s t r e t c h e d , w h i c h may r e s u l t Another source of  the femoral laterally,  synovial  pain, that  chronically  is  plica  most o f t e n l a t e r a l l y , joint,  It originates  and  tissues.  innervated  Plica  is  an  'catching'  f a t pad.  When i t  sensation.  femoral  or  the  is  becomes t h i c k e n e d and t h e p a t i e n t c o m p l a i n s or l a t e r a l  of  either medially  and e x t e n d s t o t h e o t h e r s i d e o f  i n c l u d i n g the i n f e r i o r  impinged i t  or  lateral  t i s s u e s are stressed  (James, 1979).  shape  t i s s u e w h i c h c a n become c o m p r e s s e d b e t w e e n one  p a i n and t e n d e r n e s s a c r o s s t h e m e d i a l 'snapping'  than  retroarticular  t h a t when t h e  r e l a t e d to the well  c o n d y l e s and t h e p a t e l l a .  patellofemoral  soft  i n the  i n p a i n and i n f l a m m a t i o n i n t h o s e  s y n o v i u m , may be i m p i n g e m e n t o f extension of  call  p r e s s u r e on t h e p a t e l l a d u r i n g g r o w t h may a l t e r t h e  t h e p a t e l l a , a n d u l t i m a t e l y , may l e a d t o c h a n g e s  cartilage.  is  retinaculum  d y s p l a s i a s o f t h e p a t e l l a have been n o t e d t o g e t h e r w i t h what t h e y excessive lateral  a  forces.  excessive t i g h t e n i n g , t h i c k e n i n g , or s c l e r o s i s of (Ficat  facet,  f a c e t may a l s o be a f f e c t e d by a b n o r m a l l y h i g h  forces.  by  F o r e x a m p l e , t h i s may  occur  subjected to increased  cartilage  of  c o n d y l e and a  -  94 -  The p r e s e n t - d a y k n o w l e d g e c o n c e r n i n g t h e m e c h a n i s m o f s u g g e s t s t h a t an a l t e r a t i o n may r e s u l t  in  i n the mechanics of  increased patellofemoral  a r t i c u l a r c a r t i l a g e and subchondral Basmajian (1970) b e l i e v e s movement, w h i c h r e s u l t s surrounding muscles. pain in a j o i n t , considerable  Ficat  room f o r  painful  joints.  factors  of  joint  the  tolerate.  p a i n one v o l u n t a r i l y atrophy of  inhibits  the  i n an a t t e m p t t o e x p l a i n t h e d e v e l o p m e n t  and H u n g e r f o r d  (1977) c a u t i o n t h a t t h e r e i s  greater understanding of  There i s  joint  r e a c t i o n forces which  i n weakness and p o s s i b l e  However,  PFPS  the p a t e l l o f e m o r a l  bone a r e u n a b l e t o  t h a t due t o j o i n t  pain in  the pathophysiology  a l s o a need t o r e c o g n i z e t h a t t h e  still of  etiological  P F P S a r e n u m e r o u s a n d m u l t i f a c t o r i a l , a n d a s s u c h a l s o may  be c o m p l e t e l y  understood.  of  not  - 95 -  ELECTROMYOGRAPHY  Electromyography activity  (EMG)  of muscles.  potentials  i s the graphical  recording of the electrical  I t r e p r e s e n t s t h e summation o f a l l t h e m u s c l e  a f t e r being t r a n s m i t t e d through t h e muscle t i s s u e s .  isometric contractions  result i n a non-linear increase  EMG a c t i v i t y  (Vredenbregt & Rau, 1973),  which a f f e c t  t h e r e c o r d i n g o f t h e EMG s i g n a l ,  amount o f s u b c u t a n e o u s allow considerable  however,  action  Voluntary  i n the integrated  t h e r e a r e many  such as e l e c t r o d e  factors placement,  f a t , s k i n t e m p e r a t u r e , a n d / o r m u s c l e mass  v a r i a b i l i t y among s u b j e c t s o r b e t w e e n t r i a l s  that (Winter,  1984). A biolological  a m p l i f i e r f o r t h e r e c o r d i n g o f t h e EMG c a n u s e e i t h e r  surface electrodes o r indwelling electrodes. to c e r t a i n s p e c i f i c a t i o n s frequency  i n regard t o the gain, input  S u r f a c e EMG h a s a f r e q u e n c y placed closely and B u s k i r k  together  electrodes  conform  (ISEK,  s i g n a l ; one 1980).  The e l e c t r o d e s a r e  a s recommended b y Komi  (1970) o v e r t h e motor p o i n t o f t h e muscle o r t h e muscle interface  upon t h e t h i c k n e s s o f t h e s k i n ,  Perry  r a n g e o f 5 - 2000 Hz.  ( n o more t h a n 5 c m . a p a r t )  Each e l e c t r o d e / s k i n  electrode  or 'noise'  should  impedence,  r e s p o n s e , a n d CMRR, s o t h a t i t g e n e r a t e s a ' c l e a n '  t h a t i s u n d i s t o r t e d and f r e e o f a r t i f a c t s  belly.  The a m p l i f i e r  has a f i n i t e  impedence  cleanliness of the skin,  s u r f a c e and temperature o f t h e e l e c t r o d e  depending  area o f the  paste.  (1981) and P e r r y e t a l . (1981) have s u g g e s t e d t h a t  surface  r e p r e s e n t g r o u p m u s c l e a c t i v i t y o r t h e common a c t i v i t y o f a  group o f s u p e r f i c i a l  muscles.  A l t h o u g h t h e y r e p o r t e d i n 1981 t h a t  surface  - 96  electrodes  reflect  l e s s t h a n one t e n t h o f  indwelling electrodes,  between t h e o u t p u t o f  electrodes.  H o w e v e r , more r e c e n t l y ,  surface electrodes Schwab e t a l .  surface e l e c t r o d e s are the p r a c t i c a l  electrodes their  in that  the a c t i v i t y  study comparing overground to t r e a d m i l l  difference  and i n d w e l l i n g e l e c t r o d e s ,  i n the temporal  Once t h e EMG s i g n a l p r o c e s s e d so t h a t signals. trend of  linear  indwelling recognized  indwelling  improved.  In f a c t ,  r u n n i n g and t h e use t h e y f o u n d no  significant  activity.  has been c o l l e c t e d and a m p l i f i e d , i t  i t may be more e a s i l y c o m p a r e d w i t h o t h e r  t h e EMG a n d c l o s e l y it  1979).  processing i s r e l i a b l e and  r e s e m b l e s t h e shape o f  b e a r s some r e l a t i o n s h i p Winter  is  usually  biomechanical the  the tension curve.  to the biomechanics of  (1984) a l s o b e l i e v e s t h a t l i n e a r  In  movement  envelope  t h e b e s t method f o r p r o d u c i n g an a n a l o g p a t t e r n t h a t  is  reproducible.  To f u r t h e r i m p r o v e t h e r e l i a b i l i t y o f g a i t c y c l e time base i s  t h e EMG i n g a i t a n a l y s i s ,  n o r m a l i z e d t o 100% a n d t h e l i n e a r e n v e l o p e  a v e r a g e d f r o m a number o f muscle f o r  in  of  L i n e a r e n v e l o p e EMG i s o n e m e t h o d o f p r o c e s s i n g t h a t f o l l o w s  other words, (Winter,  patterns of muscle  and  (1983) have  choice over  subject compliance to a study i s  surface electrodes  s e n s e d by  B o u i s s e t and Maton (1972) have r e p o r t e d a  relationship  that  -  is  s t r i d e s t o o b t a i n an e n s e m b l e a v e r a g e f o r  a c e r t a i n group of  subjects  (Winter,  1984; R i c h a r d s e t  the  each  al.  1985). Some a u t h o r s h a v e u s e d a maximum v o l u n t a r y i s o m e t r i c c o n t r a c t i o n a s between-day  and b e t w e e n - s u b j e c t  (Dubo e t a l . 1 9 7 6 ) .  n o r m a l i z a t i o n m e t h o d i n EMG g a i t  However, Yang and W i n t e r  studies  (1983) have r e p o r t e d  that  a  - 97  this  is  -  n o t t h e most r e l i a b l e method o f comparing a m p l i t u d e m e a s u r e s .  1984 Y a n g a n d W i n t e r i n v e s t i g a t e d f o u r t y p e s o f  n o r m a l i z a t i o n , two  w h i c h w h e r e d e r i v e d f r o m i s o m e t r i c c a l i b r a t i o n a n d two o f w h i c h c a l c u l a t e d from walking t r i a l s , variability  c o u l d be d e c r e a s e d .  n o r m a l i z i n g t o t h e peak o f mean o f  to determine  if  the  the w i t h i n - s u b j e c t ensemble average.  large reduction of between-subject  of  were  between-subject  The l a t t e r two m e t h o d s  the w i t h i n - s u b j e c t  involved  ensemble average o r t o In both c a s e s  v a r i a b i l i t y , however,  i t was a t  i n f o r m a t i o n t h a t may h a v e b e e n o b t a i n e d f r o m t h e EMG  measures.  T h e r e f o r e when t h e EMG a m p l i t u d e i s  an i n t e g r a l  the  t h e r e was a  expense of  n o r m a l i z i n g t o the ensemble average would reduce i t s  In  the  amplitude  part of  significance.  a  study  - 98 -  BIOMECHANICAL STUDIES OF RUNNING EMG s t u d i e s , e l e c t r o g o r i i o m e t e r a n d m e c h a n i c a l  power a n a l y s e s  c o n t r i b u t e d immensely t o t h e knowledge o f muscle and j o i n t running.  F o r example, c e r t a i n e l e c t r o g o n i o m e t r i c  e t a l . 1985) have d e s c r i b e d t h r e e d i m e n s i o n a l and t h e f o o t d u r i n g t r e a d m i l l  running.  and e x t e r n a l  & Blanksby  during  peak  A t a speed o f 3.5  femoris had t h e l e a s t  The v a s t u s medial i s and t h e v a s t u s  had d e c r e a s i n g muscle a c t i v i t y ,  swing.  the vastus  t h e a v e r a g e i n t e g r a t e d EMG o f t h e v a s t u s  amplitude of the three muscles. lateralis  r u n n i n g by  f e m o r i s were a l l a c t i v e a t h e e l - s t r i k e w i t h t h e i r  medial i s had t h e h i g h e s t amplitude and r e c t u s  f r o m t h e peak i n m i d s t a n c e t o  R e c t u s f e m o r i s a c t i v i t y h a d d e c r e a s e d by t h e o n s e t o f s w i n g  b u t had another b u r s t o f a c t i v i t y during  swing.  I n a n o t h e r EMG s t u d y o f r u n n i n g , Mann ( 1 9 8 2 ) r e p o r t e d activity  rotation  (1979) r e v e a l e d t h a t t h e v a s t u s l a t e r a l i s ,  ( a p p r o x i m a t e l y 12 k m / h ) ,  phase,  flexion  cycle.  a m p l i t u d e s o c c u r r i n g between h e e l - s t r i k e and h e e l - o f f .  early  have  i n v e r s i o n , a b d u c t i o n and a d d u c t i o n a t t h e f o o t and knee  medial i s and r e c t u s  m/s  (Taunton  dorsiflexion,  An EMG s t u d y o f t h e m u s c l e a c t i v i t y d u r i n g t r e a d m i l l Elliott  during  a n g u l a r motion a t t h e knee  These i n v e s t i g a t o r s  and e x t e n s i o n , v a l g u s and v a r u s , and i n t e r n a l one g a i t  activity  investigations  e l a b o r a t e d on t h e t i m i n g a n d d e g r e e s o f p l a n t a r f l e x i o n , eversion,  have  f o r 50-60% o f t h e s t a n c e p h a s e i n r u n n i n g .  quadriceps  He a l s o  noted  quadriceps a c t i v i t y a t t h e end o f swing phase, b u t u n f o r t u n a t e l y  he d i d  n o t d i s t i n g u i s h among t h e v a r i o u s m u s c l e s w i t h i n t h e q u a d r i c e p s . Mechanical Taunton,  power a n a l y s e s o f r u n n i n g ( W i n t e r ,  1982; R o b e r t s o n ,  i n press)  1983; Robertson &  h a v e shown s t r o n g e c c e n t r i c  extensor  - 99 -  muscle a c t i v i t y a t t h e knee i m m e d i a t e l y a f t e r heel midstance.  From m i d s t a n c e t o p u s h - o f f  concentrically. eccentrically.  At push-off  the extensors  From t h e r e s u l t s o f  mechanism ( W i n t e r ,  1983).  dominant but  t h e power a n a l y s e s ,  knee f l e x i o n as t h e f o o t h i t s  it  in early  has  working  been  stance  the ground - a shock  Robertson & Taunton  to  worked  t h e e x t e n s o r s were s t i l l  s u g g e s t e d t h a t t h e q u a d r i c e p s work e c c e n t r i c a l l y control  c o n t a c t a n d up  to  absorbing  (1982) r e p o r t e d  this  e x t e n s o r moment t o r a n g e b e t w e e n 1 5 0 - 3 5 0 N.m a n d t h e e n e r g y a b s o r p t i o n range between 25-105 j o u l e s .  From m i d s t a n c e t o l a t e  were c o n t r a c t i n g c o n c e n t r i c a l l y push-off.  This concentric  A t t h e v e r y end o f quadriceps  stance the  quadriceps  as t h e knee e x t e n d s i n p r e p a r a t i o n  c o n t r a c t i o n d i s s i p a t e d 11-44 j o u l e s  s t a n c e phase a s m a l l e r e c c e n t r i c  of  D u r i n g swing phase the r e s u l t s o f  1 9 8 3 ) showed a l a c k s w i n g i n g l e g and  of c o n t r i b u t i o n  t h e power a n a l y s i s  This  of  (Winter,  by t h e k n e e e x t e n s o r s t o t h e  & Blanksby  forward  (1979) p r o v i d e d e v i d e n c e t h a t  v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s were t h e most a c t i v e  absorption  the  foot.  The EMG d a t a f r o m E l l i o t t  during early  energy.  (1983).  n e g a t i v e w o r k by t h e e x t e n s o r s a b s o r b e d a p p r o x i m a t e l y 11 j o u l e s energy.  for  contraction of  d e c e l e r a t e d t h e f l e x i n g knee a c c o r d i n g t o W i n t e r  s t a n c e a n d t h e r e f o r e may be r e s p o n s i b l e  at the knee.  but to a l e s s e r e x t e n t .  f o r most o f  Rectus femoris a l s o c o n t r i b u t e d to t h i s Their  Elliott  the  quadriceps the  shock  function  s t u d y showed t h a t t h e v a s t u s m e d i a l i s  and  t h e v a s t u s l a t e r a l i s c o n t i n u e d t o be more a c t i v e t h r o u g h o u t t h e b a l a n c e the stance  to  of  phase. & Blanksby  ( 1 9 7 9 ) h a v e r e p o r t e d t h e EMG a c t i v i t y  f e m o r i s d u r i n g swing as a c t i n g as a h i p f l e x o r .  in  rectus  Power a n a l y s e s o f  the  hip  - 100 -  d u r i n g r u n n i n g have n o t r e v e a l e d a p a t t e r n t h a t i s c o n s i s t e n t enough t o r e p o r t e d a n d t h e r e f o r e c a n n o t c o n f i r m t h e EMG r e s u l t s .  be  -  101 -  ISOKINETIC DYNAMOMETRY  The a b i l i t y activity  t o measure muscle s t r e n g t h a s i t r e l a t e s t o f u n c t i o n a l  i s essential  t o o u r u n d e r s t a n d i n g o f normal  performance.  Muscle  s t r e n g t h c a n be d e f i n e d a s t h e a b i l i t y o f a s i n g l e m u s c l e o r a muscle group t o e x e r t maximal f o r c e  i n a single voluntary effort  Ramos, 1 9 8 0 ) o r a s M u r r a y e t a l . component,  o r torque,  (1980) d e f i n e  produced by a m u s c l e .  i t - i t i s the rotational  T h i s s t r e n g t h c a n be measured  i s o m e t r i c a l l y , which measures t h e muscle f o r c e angle,  (Knapik and  only a t a s p e c i f i c  o r i t can be measured under t h e dynamic c o n d i t i o n s  isokinetic  joint  of isotonic or  activity.  I s o k i n e t i c muscle a c t i v i t y and P e r r i n e ,  and T h i s t l e  i s a r e l a t i v e l y new c o n c e p t ,  and c o w o r k e r s  introduced i n 1967.  which  Hislop  Perrine  defined i s o k i n e t i c e x e r c i s e as e x e r c i s e which occurs a g a i n s t a load a l l o w s movement a t a m e c h a n i c a l l y f i x e d r a t e o f s p e e d a n d resistance  inherently proportional  developing capacity  t o t h e m u s c l e ' s dynamic  a t every p o i n t i n i t s range.  r e s i s t a n c e s u p p l i e d by an e l e c t r o m e c h a n i c a l dynamometer, a l l o w s  f o r thecontinuously  maximal  tension  changing muscle tension  that  Since the late  dynamometer (Cybex) was i n t r o d u c e d t o N o r t h  o f constant speed, i n v i v o .  f o r c e c u r v e , t h e work,  have been measured  offers  d e v i c e , c a l l e d an i s o k i n e t i c  A m e r i c a i t h a s been p o s s i b l e t o s t u d y t h e m e c h a n i c a l under c o n d i t i o n s  which  The accommodating  o c c u r s w i t h c h a n g i n g l e v e r a g e t h r o u g h o u t t h e movement. 1 9 6 0 ' s when a n i s o k i n e t i c  (1968)  power,  concentrically.  properties  Such p r o p e r t i e s  o f muscle  as the  and endurance c a p a c i t i e s o f m u s c l e  - 102 -  Using the i s o k i n e t i c  dynamometer, r e s e a r c h e r s have s t u d i e d t h e  relationship  between a n g u l a r v e l o c i t y  contractions  (Thortensson e t a l . 1976).  reaffirmed the c l a s s i c a l  and t o r q u e v a l u e s d u r i n g  force-velocity  These i n v e s t i g a t i o n s  t h e i r maximal  30°,  s t u d i e d 72 m e n , f r o m 2 0 - 8 6 y e a r s ,  i s o m e t r i c t o r q u e and maximal c o n c e n t r i c  f o r the r i g h t quadriceps 45° a n d 6 0 ° , w h i l e  and h a m s t r i n g s . isokinetic  have  r e l a t i o n s h i p , which s t a t e s t h a t as  the v e l o c i t y of muscle shortening increases the muscle force Murray e t a l . (1980)  concentric  Isometric  decreases.  to determine  isokinetic  torques  s t r e n g t h was t e s t e d a t  s t r e n g t h was m e a s u r e d a t 3 6 ° / s .  G e n e r a l l y t h e i r f i n d i n g s w e r e t h a t t h e mean m a x i m a l t o r q u e v a l u e s h i g h e s t f o r t h e y o u n g e s t g r o u p o f men ( 2 0 - 3 5 y e a r s ) strength decreased with  increasing age.  were  a n d t h a t maximum  T h e y a l s o f o u n d t h a t t h e mean  maximum t o r q u e f o r t h e q u a d r i c e p s w a s g r e a t e s t a t 4 5 ° , t h a t t h e mean maximum t o r q u e  f o r the quadriceps  f r o m t h e y o u n g e s t g r o u p o f men w a s 2 , 2 2 7  k g - c m ( 2 1 8 . 2 N.m) a n d t h a t t h e h a m s t r i n g s m a x i m a l t o r q u e r a n g e d 43-61% o f t h e maximal q u a d r i c e p s Studies  from  torque.  i n which the strength o f the quadriceps  and h a m s t r i n g s  have  b e e n d e t e r m i n e d i n y o u n g women h a v e b e e n c a r r i e d o u t by a t l e a s t t w o groups o f i n v e s t i g a t o r s . females, normal  In these s t u d i e s t h e s u b j e c t s were  non-athletic  as t h e i n v e s t i g a t o r s were a t t e m p t i n g t o e s t a b l i s h a b a s e - l i n e  data f o r that  Wyatt and Edwards on t h e i s o k i n e t i c  of  population. ( 1 9 8 1 ) s t u d i e d 50 f e m a l e s u b j e c t s a g e d 2 5 - 3 4 y e a r s  dynamometer a t v e l o c i t i e s  o f 6 0 ° / s , 180°/s a n d 300°/s t o  d e t e r m i n e t h e peak t o r q u e s o f t h e i r q u a d r i c e p s  and h a m s t r i n g s .  A t 60°/s  - 103 -  t h e mean p e a k q u a d r i c e p s  t o r q u e was 79 f t - l b  h a m s t r i n g s t o r q u e was 56 f t - l b ft-lb  (76 N.m).  ( 7 7 N.m) f o r t h e q u a d r i c e p s  hamstrings.  A t 180°/s t h e v a l u e s w e r e 57  a n d 45 f t - l b  A t 300°/s mean peak q u a d r i c e p s  a n d mean p e a k h a m s t r i n g s t o r q u e was 3 2 f t - l b to the functional  ( 1 0 7 N.m) a n d t h e mean peak  ( 6 1 N.m) f o r t h e  t o r q u e w a s 38 f t - l b (43 N.m).  In order t o  dynamometer, a s t h e y  h a v e r e p o r t e d t h a t t h e k n e e e x t e n d s a t a v e l o c i t y o f 230°/s  be much  relate  a c t i v i t y o f w a l k i n g , t h e s e a u t h o r s recommended a  v e l o c i t y b e t w e e n 2 0 0 a n d 300°/s o n t h e i s o k i n e t i c  walking.  ( 5 2 N.m)  The a n g u l a r v e l o c i t y  during  a t t h e knee d u r i n g r u n n i n g would  therefore  higher.  D i b r e z z o e t a l . ( 1 9 8 4 ) s t u d i e d t h e peak t o r q u e o f t h e q u a d r i c e p s a n d h a m s t r i n g s i n 241 u n t r a i n e d f e m a l e s aged 1 8 - 2 8 y e a r s . done a t o n l y o n e v e l o c i t y - 6 0 ° / s . 94.47 f t - l b the  Their  t e s t i n g was  T h e y f o u n d t h e mean peak t o r q u e s  ( 1 3 0 N.m) f o r t h e q u a d r i c e p s  and 5 1 . 9 4 f t - l b  t o be  ( 7 1 N.m) f o r  hamstrings. I n v e s t i g a t o r s h a v e a l s o a t t e m p t e d t o d e t e r m i n e t h e r a t i o o f peak  concentric  torque,  o r s t r e n g t h , between t h e q u a d r i c e p s  G o s l i n and C h a r t e r i s dependent.  ratio  is  speed  They f o u n d t h a t a t an a n g u l a r v e l o c i t y o f 30°/s t h e  quadriceps/hamstrings .50).  (1979) have s u g g e s t e d t h a t t h i s  and h a m s t r i n g s .  Moffroid  ratio  i s 2 : 1 ( h a m s t r i n g s / q u a d r i c e p s o r H/Q  ratio  e t a l . ( 1 9 6 9 ) r e p o r t e d t h e same H/Q r a t i o a t 23°/s a n d  D i b r e z z o e t a l . ( 1 9 8 5 ) f o u n d t h e same r a t i o a t 6 0 ° / s .  However, Wyatt and  Edwards  . 7 9 a t 180°/s a n d  (1981) r e p o r t e d t h e r a t i o s t o be .71 a t 60°/s,  . 8 5 a t 300°/s i n y o u n g f e m a l e s a n d . 7 2 a t 6 0 ° / s ,  . 7 8 a t 180°/s a n d . 8 3 a t  -  300°/s f o r y o u n g m e n . difference  104 -  They c o n c l u d e d f r o m t h e i r r e s u l t s t h a t  between t h e s t r e n g t h i n t h e f l e x o r s and e x t e n s o r s d e c r e a s e s  the v e l o c i t y  increases,  angular v e l o c i t y . relationship that there i s  of  In h i s  activity,  r e v i e w o f 50 r e p o r t s p e r t a i n i n g t o t h e  t h e knee f l e x o r s  under a l l  and e x t e n s o r s , Nosse  circumstances, which  generally accepted guideline as t h e i p s i l a t e r a l  (1982)  knee e x t e n s o r s  (Scudder,  t o s t u d y c o n c e n t r i c m u s c l e a c t i v i t y , Komi d e s i g n e d an i s o k i n e t i c From h i s  force  an i s o k i n e t i c  i n c r e a s e d and t h e c o n c e n t r i c  and  the r e l i a b i l i t y  and v a l i d i t y o f  f o c u s e d on t h r e e o f velocity,  its  and f o r c e m e a s u r i n g s y s t e m s .  also  Kinetic  Med-ex o f Canada,  Inc.,  and w o r k .  measures  In a study  and R i c h a r d s  l e v e r arm p o s i t i o n ,  of  (1986) lever  arm  They f o u n d t h a t t h e d i f f e r e n c e s  t h e f o r c e m e a s u r e m e n t s w e r e 3.2% o r l e s s ,  *  the  muscle.  t h e KINCOM, F a r r e l l  primary functions:  concentric  increased  C o m m u n i c a t o r E x e r c i s e S y s t e m (KINCOM)* h a s b e e n d e v e l o p e d w h i c h torque,  had  isokinetic  dynamometer c a l l e d t h e  and e c c e n t r i c m u s c l e power,  strong  dynamometer  force decreased,  r e l a t i o n s h i p of  I n N o r t h A m e r i c a an i s o k i n e t i c  the  ( 1 9 7 3 ) r e p o r t e d t h a t he  forearm muscles using h i s  confirming the f o r c e - v e l o c i t y  for  1980).  d y n a m o m e t e r , Komi f o u n d t h a t a s v e l o c i t y o f c o n t r a c t i o n  concentric  strength  s h o u l d be 60% a s  dynamometer t o r e c o r d b o t h e c c e n t r i c  study of  same  concludes  i s contrary to  t h a t t h e knee f l e x o r s  E v e n more r e c e n t l y t h a n t h e d e v e l o p m e n t o f  eccentric  tested at the  n o t a f i x e d s t r e n g t h r a t i o t h a t c o u l d be a p p r o p r i a t e  each i n d i v i d u a l  as  a n d t h a t t h e r a t i o s a r e s i m i l a r f o r men a n d women  i n t h e same a g e g r o u p , w i t h s i m i l a r l e v e l s o f  forces.  the  t h e l e v e r arm s p e e d was  Coquitlam, B.C.,  Canada  within  in  -  1.5% o f  105 -  t h e t a r g e t s p e e d a n d t h e r e was no d i f f e r e n c e  measurement.  in  position  T h e y c o n c l u d e d t h a t t h e d i s c r e p a n c i e s b e t w e e n t h e KINCOM a n d  the external  m e a s u r i n g d e v i c e s w e r e s m a l l e n o u g h t h a t t h e y c o u l d be due  calibration error  a n d w e r e n o t due t o i n a c c u r a c y o f  Up t o now m o s t o f which c l o s e l y  in functional  been g a t h e r e d f r o m c o n c e n t r i c m u s c l e t e s t i n g . with the advent of  t h e KINCOM.  the i n f o r m a t i o n r e g a r d i n g dynamic muscle  approximates muscle a c t i o n  newer i s o k i n e t i c  However,  devices that  testing,  activities, i t would  information  and c o n t r a l a l t e r a l  eccentrically, a l s o be  l i m b s t r e n g t h r e l a t i o n s h i p s may be  and e c c e n t r i c / c o n c e n t r i c  mechanical primarily  and studied  r e l a t i o n s h i p s w i t h i n a muscle  properties  the muscles at the knee, are  can  energy absorbers throughout there i s  the  o f e c c e n t r i c work because t h e knee m u s c l e s the g a i t c y c l e  (Winter,  a l s o c o n c e n t r i c w o r k by b o t h t h e f l e x o r s  d u r i n g g a i t , w h i c h m u s t n o t be o v e r l o o k e d i f made.  appear  identified.  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