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Control of subtalar motion with the use of ski-boot footbeds Greenberg, Susan B 1990

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CONTROL OF SUBTALAR MOTION WITH THE USE OF SKI-BOOT FOOTBEDS By SUSAN B. GREENBERG B.A., York U n i v e r s i t y , 1986 THESIS SUBMITTED IN PARTIAL FULFILLMENT THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION in THE FACULTY OF GRADUATE STUDIES (School o f P h y s i c a l  Education)  We accept t h i s t h e s i s as c o n f o r m i n g to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA JUNE, 1990 ^ Susan B. Greenberg  In  presenting  this thesis  in partial fulfilment of  the  requirements  for  an  advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. copying  of this thesis for scholarly  department  or  by  his  or  her  I further agree that permission for  purposes  extensive  may be granted by the head of my  representatives.  It  is  understood  that  copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of P H V S J C A l  E>>OCAT/^  The University of British Columbia Vancouver, Canada Date  DE-6 (2/88)  ABSTRACT R e s e a r c h shows t h a t up t o 80% of r e c r e a t i o n a l s k i e r s have lower l i m b a l i g n m e n t s which can impede t h e i r a b i l i t y turn t h e i r skis properly  (Subotnick,1982).  The  to  most  d i f f i c u l t of t h e s e alignment problems t o c o n t r o l w i t h i n a s k i - b o o t i s the v a r u s a l i g n m e n t of the s u b t a l a r (Macintyre  and Matheson, 1988).  The  f o o t b e d s made s p e c i f i c a l l y f o r use  joint  use o f custom molded  i n s i d e of s k i b o o t s  has  been s u g g e s t e d as one method of compensating f o r a v a r u s a l i g n e d f o o t . T h i s study compared the e f f e c t i v e n e s s o f b r a n d o f custom molded s k i boot f o o t b e d  w i t h t h a t of a non-  custom i n s o l e i n c o n t r o l l i n g the motions o f the lower a s s o c i a t e d with subtalar varus.  one  limb  S p e c i f i c a l l y t h e s e motions  were t h o s e of the r e a r f o o t and the n a v i c u l a r t u b e r c l e ,  along  w i t h t h e a l i g n m e n t of the t i b i a l t u b e r o s i t y w i t h r e s p e c t the m i d - l i n e of the s k i b o o t . given the opportunity  to  In a d d i t i o n , s u b j e c t s were  to assess t h e i r s u b j e c t i v e f e e l i n g s of  edge c o n t r o l , p a i n , and  f a t i g u e w h i l e s k i i n g w i t h b o t h the  custom molded f o o t b e d s and non-custom i n s o l e s . The  s u b j e c t group f o r t h i s study c o n s i s t e d of  advanced l e v e l a d u l t s k i e r s who  13  demonstrated more t h a n  degrees o f s u b t a l a r v a r u s when non-weight b e a r i n g .  three  Each  s u b j e c t r e c e i v e d a p a i r of custom molded s k i boot f o o t b e d s at t h e b e g i n n i n g Ski  of the  study.  b o o t s t h a t had been cut away at the r e a r and  the  m e d i a l s i d e were used i n the l a b o r a t o r y i n o r d e r t o observe t h e motions o f the n a v i c u l a r t u b e r c l e and the r e a r f o o t ii  as  the  subject  transferred  t h e i r weight i n a simulated  skiing  motion. The  r i g h t and l e f t  navicular  tubercle,  tibial  tubercle,  and t h e i n s e r t i o n o f t h e A c h i l l e s a t t h e c a l c a n e u s o f e a c h subject  were l o c a t e d  sufficient practice  by p a l p a t i o n  and marked.  After  of the weight t r a n s f e r motion,  trials  o f e a c h l a n d m a r k were p h o t o g r a p h e d u s i n g  film.  The  subjects  non-custom  insoles  footbeds.  The  made b e t w e e n  were f i r s t  s l i d e s were d i g i t i z e d  Statistical t h e r e was  during the  insoles.  The  (p=0.000)  T h e r e was  amount o f r e a r f o o t The t i b i a l  (p=0.000) custom  insoles.  f o r both the s t a r t  and  (p=0.000)  indicated  navicular  a n g l e was and e n d  no s t a t i s t i c a l  motion with  to the  significantly  (p=0.000)  f o o t b e d s as c o m p a r e d  positions  t o t h e non-  difference  between  m o t i o n a l l o w e d by e i t h e r t y p e o f  tubercle  was  positioned  c l o s e r to the mid-line footbeds than with These  traveled.  f o o t b e d s as c o m p a r e d  rearfoot  t h e use o f t h e custom  insole.  the  less  use o f t h e custom molded  custom i n s o l e s . the  and c o m p a r i s o n s w e r e  from t h e s t a r t t o t h e end p o s i t i o n s  l e s s at both the s t a r t with  the  molded  a n a l y s e s o f the group r e s u l t s  significantly  the s h i f t  non-custom  using  o f t h e l a n d m a r k s as w e l l a s f o r t h e r a n g e s o f  motion t h r o u g h which the landmarks  that  the custom  t h e two t y p e s o f i n s o l e s  end l o c a t i o n s  35mm s l i d e  photographed while  and a g a i n u s i n g  two  significantly  o f t h e s k i b o o t when  t h e use o f t h e  r e s u l t s indicate that  iii  using  non-custom  t h e custom  f o o t b e d s do  m a i n t a i n the do  non-custom  subtalar  the  skiing section  comparing the  T h e r e was  ratings  pain experienced with T h e r e was  race times f o r the  as  compared t o the  no  g i v e n by the  a statistically  in  ski  study the better  resulting in less fatigue  custom i n s o l e s .  The  of the  c u s t o m f o o t b e d s as p r o v i d i n g  (p=0.000) and  use  statistical the  of e i t h e r type of  g r o u p when u s i n g t h e  level insole.  custom  (p=0.000) footbeds  iv  m o t i o n more  I t appears t h a t  r e d u c i n g the  experienced.  custom molded  subtalar  motion enhances the and  of  insoles.  able to control  edge c o n t r o l  control  s i g n i f i c a n c e when  group f o r the  e f f e c t i v e l y t h a n a non-custom i n s o l e . of s u b t a l a r  edge  (p=0.000) t h a n n o n -  r e s u l t s of t h i s study i n d i c a t e that  increasing  than  subjects  s i g n i f i c a n t improvement  non-custom  boot footbeds are  control  position  insoles.  During the rated  j o i n t i n a more n e u t r a l  this  s k i i n g experience amount o f  fatigue  by  TABLE OF CONTENTS ABSTRACT  i i  LIST OF FIGURES  viii  ACKNOWLEDGEMENTS 1.  2.  ix  INTRODUCTION  1  Statement o f t h e Problem  2  Hypotheses  3  S i g n i f i c a n c e o f t h e Study  4  D e f i n i t i o n o f Terms  4  Delimitations  6  Assumptions  7  REVIEW OF LITERATURE  8  Mechanics o f S k i i n g  3.  8  Lower Limb A l i g n m e n t and S k i i n g  10  O r t h o t i c s , Footbeds, and S k i i n g  12  Footbed C o n s t r u c t i o n  13  Pain Analysis  15  PROCEDURES  18  Subjects  18  Research Design  18  Laboratory  19  Section  I n i t i a l Assessment  19  Footbed P r e p a r a t i o n  20  S k i Boot P r e p a r a t i o n  20  Data C o l l e c t i o n  22  Data A n a l y s i s  24  S t a t i s t i c a l Analysis  24  v  Skiing Section  4.  5.  24  Data C o l l e c t i o n  24  Data A n a l y s i s  26  S t a t i s t i c a l Analysis  26  RESULTS AND DISCUSSION  27  D e s c r i p t i o n of Subjects  27  Laboratory Section  27  N a v i c u l a r Drop  27  Rearfoot Angle  34  T i b i a l Rotation  36  Summary  38  Skiing Section  39  Edge C o n t r o l  39  Pain  39  Fatigue  40  Timed Runs  40  Summary  40  CONCLUSIONS AND RECOMMENDATIONS  44  Conclusions  46  Recommendations  47  REFERENCES  48  APPENDIX A - DETERMINATION OF LOWER LIMB ALIGNMENT  50  APPENDIX B - FOOTBED MOLDING PROCEDURE  51  APPENDIX C - GENERAL DESCRIPTIVE DATA FOR ALL SUBJECTS...53 APPENDIX D - COMPLETE NAVICULAR DATA  54  APPENDIX E - COMPLETE REARFOOT DATA.  61  APPENDIX F - COMPLETE TIBIAL TUBEROSITY DATA  64  vi  APPENDIX G - COMPLETE RATINGS DATA APPENDIX H - COMPLETE RACE DATA  vii  LIST OF FIGURES la. lb.  M e d i a l Window o f S k i Boot E x p o s i n g t h e N a v i c u l a r Tubercle Rear Window o f S k i Boot E x p o s i n g  21  the I n s e r t i o n o f  t h e A c h i l l e s at the Calcaneus  21  lc.  F r o n t View o f S k i Boot With T i b i a l T u b e r o s i t y  21  2a.  N a v i c u l a r S t a r t / E n d P o s i t i o n s , X D i r . , R i g h t Foot....29  2b.  N a v i c u l a r S t a r t / E n d P o s i t i o n s , X D i r . , L e f t Foot  3a.  N a v i c u l a r S t a r t / E n d P o s i t i o n s , Y D i r . , R i g h t Foot....30  3b.  N a v i c u l a r S t a r t / E n d P o s i t i o n s , Y D i r . , L e f t Foot  4.  N a v i c u l a r Motion  i n the X D i r e c t i o n  ...32  5.  N a v i c u l a r Motion  i n the Y D i r e c t i o n  33  6a.  R e a r f o o t A n g l e s at S t a r t and End,  R i g h t Foot  35  6b.  R e a r f o o t A n g l e s at S t a r t and End,  L e f t Foot  35  7.  T i b i a l T u b e r c l e , H o r i z o n t a l D i s t a n c e From M i d l i n e . . . . 37  8a.  Edge C o n t r o l R a t i n g s f o r Short Radius Turns  41  8b.  Edge C o n t r o l R a t i n g s f o r Long Radius Turns  41  9a.  Pain Ratings  42  9b.  Fatigue Ratings  42  10.  Race R e s u l t s  43  viii  29  30  ACKNOWLEDGEMENT S  I would l i k e t o acknowledge t h e c o n t r i b u t i o n s o f s e v e r a l p e o p l e w i t h o u t whom t h i s p r o j e c t would n o t have been made p o s s i b l e . To my t h e s i s and graduate a d v i s o r , Dr. Jack Taunton f o r his  d i r e c t i o n , enthusiasm, and encouragement as w e l l as f o r  his  e x t e n s i v e network  of valuable resource people.  To Dr. James M a c i n t y r e f o r h i s i n s i g h t , e x p e r t i s e , and c o n t r i b u t i o n s i n the area of s k i research. To Dr. D a v i d Sanderson  f o r h i s e x p e r t i s e and d e v o t i o n  t o h i s f i e l d , h i s uncompromising  s t a n d a r d s , and most  i m p o r t a n t l y f o r h i s a p p r o a c h a b i l i t y and genuine i n t e r e s t i n his  students. To Mr. P a u l P a r i s who has t h e a b i l i t y t o g e t water  from  a stone i n t h e form o f time and equipment d o n a t i o n s and whose own s a c r i f i c e o f v a l u a b l e time and e f f o r t was t h e t r u e turning point for this project. To my f r i e n d s a t U.B.C, p a r t i c u l a r l y t h o s e i n t h e Biomechanics L a b o r a t o r y who k i n d l y adopted an o u t s i d e r and gave me a home base from which t o o p e r a t e . F i n a l l y , t o my f a m i l y who support me i n a l l t h a t I undertake. Support p r o v i d e d by Bud Ryckman/ MJD A g e n c i e s , N o r v i n c a Inc.,  P a r i s O r t h o t i c s , John C o l p i t t s , D a v i d S t e e r s , and  Grouse Mountain R e s o r t s L i m i t e d i s g r a t e f u l l y  ix  acknowledged.  Chapter 1 INTRODUCTION  Over two m i l l i o n Canadians p a r t i c i p a t e i n t h e s p o r t o f alpine skiing.  S k i i n g i s unique i n t h a t i t i s t h e o n l y  s p o r t i n w h i c h a l e v e r system i s r i g i d l y a t t a c h e d t o t h e body. The  T h i s system c o n s i s t s o f t h e s k i , b i n d i n g , and boot.  s k i boot i s t h e main l i n k i n t r a n s f e r r i n g f o r c e s from  the s k i e r t o the s k i . The  a b i l i t y of the skier t o ride a f l a t s k i  ( i e . m a i n t a i n i n g ground c o n t a c t w i t h b o t h edges o f t h e s k i simultaneously) without a l t e r i n g t h e i r n a t u r a l stance i s important.  From t h i s p o s i t i o n t h e s k i e r i s a b l e t o p i v o t ,  edge, and p r e s s u r e t h e s k i through minimal  leg actions.  a carved t u r n with  The s k i e r whose n a t u r a l s t a n c e  places  them on t h e i r s k i edges has d i f f i c u l t i e s i n i t i a t i n g a t u r n . R e s e a r c h i n d i c a t e s t h a t up t o 80% o f r e c r e a t i o n a l s k i e r s have lower l i m b a l i g n m e n t s  which p r e v e n t  f l a t s k i w h i l e i n a n a t u r a l stance  them from r i d i n g a  (Subotnick, 1982).  The  most common c o n d i t i o n s which c o n t r i b u t e t o t h e i n a b i l i t y t o r i d e a f l a t s k i are varus alignments  o f t h e t i b i a and f o o t .  T h i s r e s e a r c h i n v e s t i g a t e d one suggested  method f o r  overcoming t h e problems a s s o c i a t e d w i t h a v a r u s alignment o f the f o o t . The need t o compensate f o r i m p e r f e c t l e g a l i g n m e n t s has r e s u l t e d i n t h e improvement o f s k i boot d e s i g n .  Adjustable  boot c u f f s can be a l i g n e d t o approximate t h e angle o f t h e 1  t i b i a w h i l e a l l o w i n g the base of the boot t o remain l e v e l . The  s k i e r w i t h a l l but the most severe amounts o f t i b i a  vara  i s thus a b l e t o r i d e a f l a t s k i . F o r e f o o t and r e a r f o o t v a r u s t y p i c a l l y r e s u l t i n e x c e s s i v e p r o n a t i o n d u r i n g weight b e a r i n g .  Excessive  p r o n a t i o n i s i d e n t i f i e d by the accompanied i n c r e a s e o f t i b i a l r o t a t i o n , a decreased  ability  t o reduce the  t r a n s m i s s i o n o f shock- up the l e g , and d i f f i c u l t y r e s u p i n a t i n g during unweighting. difficult  in  Excessive pronation i s a  c o n d i t i o n t o c o r r e c t w i t h i n a s k i boot.  The  n a t u r e o f t h e modern s k i boot i s such t h a t the r i g i d  plastic  s h e l l and t i g h t f i t can i n c r e a s e the amount o f p r o n a t i o n e x p e r i e n c e d by most s k i e r s by c a u s i n g the l o n g i t u d i n a l to  flatten.  footbeds  The manufacturers  arch  o f custom molded s k i boot  c l a i m t h a t t h e s e d e v i c e s can m a i n t a i n t h e f o o t i n a  n e u t r a l p o s i t i o n and c o n t r o l excess p r o n a t i o n  thereby  r e d u c i n g t h e p a i n , f a t i g u e , and edge c o n t r o l problems associated with excessive pronation Superfeet  Tech. Manual).  supporting these  ( P e t e r s o n Tech. Manual,  To date t h e r e are no r e l i a b l e  data  beliefs.  Statement o f the Problem T h i s r e s e a r c h was  d e s i g n e d t o i n v e s t i g a t e the  e f f e c t i v e n e s s o f one type o f custom molded f o o t b e d t o c o n t r o l r e a r f o o t motion, n a v i c u l a r drop, and  tibial  r o t a t i o n , t h r e e events a s s o c i a t e d w i t h p r o n a t i o n . o f the study was  The  t o o b t a i n q u a n t i t a t i v e measures o f t h e 2  focus  ability in  of the  an e f f o r t  footbed to c o n t r o l motion w i t h i n a s k i boot  t o d e t e r m i n e t h e mechanism o f c o n t r o l .  s e c o n d f o c u s was  A  the q u a n t i f i c a t i o n of the s u b j e c t i v e  f e e l i n g s o f edge c o n t r o l ,  p a i n , and  f a t i g u e which to  date  have o n l y been r e p o r t e d a n e c d o t a l l y .  Hypotheses 1.  I t was  hypothesized  that there i s s i g n i f i c a n t l y  l e s s p r o n a t i o n , as m e a s u r e d by m o t i o n , and  c)tibial  r o t a t i o n while weight bearing w i t h  p l a c e d on c u s t o m f o o t b e d s 2.  I t was  decrease i n the t h e use  a ) n a v i c u l a r drop, b ) r e a r f o o t  than  hypothesized  on n o n - c u s t o m  that there i s a  l e v e l s of perceived  of a custom footbed  f o o t and  feet  insoles. significant leg pain  with  as c o m p a r e d t o a n o n - c u s t o m  insole. 3.  I t was  decrease i n the  hypothesized  l e v e l of perceived  of a custom footbed 4.  I t was  i n c r e a s e i n the  I t was  level  significant  foot f a t i g u e w i t h the  that there  is a  significant  as c o m p a r e d t o a n o n - c u s t o m  hypothesized  t h a t the  3  use  insole.  increased level  i n i m p r o v e d p e r f o r m a n c e on  course.  use  insole.  o f p e r c e i v e d edge c o n t r o l w i t h t h e  edge c o n t r o l w o u l d r e s u l t race  is a  as c o m p a r e d t o a n o n - c u s t o m  hypothesized  of a custom footbed 5.  that there  of a  timed  S i g n i f i c a n c e o f the Study T h i s study s e r v e d t o t e s t the manufacturers t o t h e e f f e c t i v e n e s s of custom molded footbeds c o n t r o l l i n g the events improving  c l a i m s as in  associated with pronation  s k i i n g a b i l i t y and enjoyment.  i n t e n t i o n o f t h i s study t o develop  I t was  and the  a method f o r q u a n t i t a t i v e  assessment o f motion w i t h i n a s k i boot i n o r d e r t o determine t h e e f f e c t i v e n e s s o f s k i boot  footbeds.  D e f i n i t i o n o f Terms F o r e f o o t V a r u s . M e d i a l b o r d e r of the f o o t i s r a i s e d a t t h e m e t a t a r s a l heads w h i l e i n a non-weight b e a r i n g p o s i t i o n (Root e t a l . ,  1971).  S u b t a l a r Varus. M e d i a l border o f the f o o t i s r a i s e d at the h e e l w h i l e i n a non-weight b e a r i n g p o s i t i o n al.,  (Root e t  1971). P r o n a t i o n . P o s i t i o n d e s c r i b e d by a n k l e e v e r s i o n ,  a b d u c t i o n , and d o r s i f l e x i o n ; i n t e r n a l r o t a t i o n o f the o c c u r s secondary t o s u b t a l a r e v e r s i o n  tibia  (McKenzie, Clement,  and Taunton, 1985). N a v i c u l a r Drop. The  f o r w a r d and downward motion o f t h e  n a v i c u l a r t u b e r c l e t h a t t y p i c a l l y o c c u r s w i t h weight bearing. Rearfoot Angle.  The  angle o f i n s e r t i o n o f the A c h i l l e s  tendon a t t h e c a l c a n e u s w i t h r e s p e c t t o an i m a g i n a r y which i s p e r p e n d i c u l a r t o the ground.  4  line  T i b i a l Rotation. with The  respect tibial  to the  The  alignment of the  mid-seam o f t h e  tuberosity  i s rotated  collapses with pronation. of the  subtalar  This  toe  tibial  piece  tibia  despite  of a s k i boot.  o u t w a r d as t h e  arch  r o t a t i o n o c c u r s as  j o i n t ' s attempts to maintain  alignment w i t h the  tuberosity  the  a result  proper  e f f e c t s of  pronation.  O r t h o t i c . Device designed to a s s i s t i n biomechanical c o n t r o l of the  lower extremity;  neutral position  (Macintyre  s t a b i l i z e s the  and  Matheson,  joint  in a  1988).  Non-custom I n s o l e . Removeable i n s o l e found i n s i d e s k i boots. Custom M o l d e d S k i Boot F o o t b e d . Custom molded t h a t b e g i n s as shaped t o  The  c o r k and the  use  shaped b l a n k .  i n d i v i d u a l foot  m a i n t a i n e d by 1987).  a foot  Insoles  contours while  footbed used i n t h i s  s t u d y was  The  heated is  (Colpitts,  constructed  of  neutral position  A 10cm  by  horizontal  s t o p s a t b o t h ends at r i g h t a n g l e s t o t h e  a d d i t i o n of d e s c r i p t i v e terms produces a g r a p h i c  scale  and  suction.  H o r i z o n t a l V i s u a l Analogue Scale. l i n e with  foot  some m e t h o d i n a n e u t r a l p o s i t i o n  molded i n a non-weight b e a r i n g , of  the  are  insole  ( S c o t t and  Huskisson,  1979).  5  line. ratings  Delimitations R e s u l t s o f t h i s study were r e s t r i c t e d t o a d u l t , advanced l e v e l s k i e r s who e x h i b i t e d more than t h r e e o f s u b t a l a r v a r u s i n each f o o t .  degrees  The r e s u l t s were a l s o  r e s t r i c t e d t o t h e one make and model o f custom molded footbed  t e s t e d as w e l l as t h e make and model o f t e s t boot  used i n t h e l a b o r a t o r y .  An e f f o r t was made t o s t a n d a r d i z e  t h e make and model o f t e s t b o o t s as S c h a f f e t a l . (1987) have shown t h a t w h i l e t h e r e  i s l i t t l e o r no v a r i a b i l i t y i n  t h e f l e x p a t t e r n and p r e s s u r e the same boot, t h e r e makes.  p r o f i l e s of various s i z e s of  i s v a r i a b i l i t y between boot s t y l e s and  The e f f e c t i v e n e s s o f t h e f o o t b e d s was r e s t r i c t e d t o  t h e a b i l i t i e s o f t h e t e c h n i c i a n s t o work w i t h t h e p r o d u c t . V a r i a b i l i t y i n c o n s t r u c t i o n was m i n i m i z e d by u s i n g o n l y two t e c h n i c i a n s t o make a l l t h e f o o t b e d s f o r t h i s  study.  A n a l y s i s o f motion i n s i d e o f t h e s k i b o o t s was c o n f i n e d to laboratory conditions.  S k i i n g maneuvers c r e a t e  forces  which a r e n o t e a s i l y reproduced i n t h e l a b ( S c h a t t n e r e t al.,  1985).  Windowing o f t h e s k i b o o t s m i n i m a l l y  altered  f l e x and support c h a r a c t e r i s t i c s . A c c u r a c y o f t h e r e s u l t s may have been a f f e c t e d by t h e s e e x p e r i m e n t a l  6  conditions.  Assumptions This research  o p e r a t e d under t h e assumption t h a t i f  custom molded s k i boot f o o t b e d s d i d reduce p a i n and f a t i g u e , and  i n c r e a s e edge c o n t r o l they d i d so by r e d u c i n g  Although the l i t e r a t u r e speculated  pronation.  that t h i s i s the  u n d e r l y i n g mechanism o f t h e i r e f f e c t i v e n e s s t h e r e were no r e l i a b l e d a t a a v a i l a b l e at t h e time o f t h i s s t u d y . I t was assumed t h a t each s u b j e c t was a t a s k i i n g  level  which was s u f f i c i e n t l y h i g h so as t o a l l o w them t o a c c u r a t e l y judge t h e s u b t l e d i f f e r e n c e s i n edge c o n t r o l , p a i n , and f a t i g u e e x p e r i e n c e d w i t h t h e use o f v a r i o u s of i n s o l e s .  I n t h e l a b o r a t o r y i t was assumed t h a t a l l  markers were p r o p e r l y p o s i t i o n e d on t h e i r landmarks.  7  intended  types  Chapter 2 REVIEW OF LITERATURE T h i s r e v i e w i s d i v i d e d i n t o f i v e major s e c t i o n s : (a) mechanics o f s k i i n g ; skiing;  (b) lower l i m b alignment  (c) o r t h o t i c s , f o o t b e d s ,  construction;  and s k i i n g ;  (d)  and footbed  (e) p a i n a n a l y s i s .  Mechanics o f S k i i n g The  c a r v e d p a r a l l e l t u r n i s the most e s s e n t i a l s k i l l  alpine skiing.  P i v o t i n g , edging,  of  and p r e s s u r e c o n t r o l are  t h e t h r e e elements i n v o l v e d i n the t u r n .  Ankle e v e r s i o n ,  v a l g u s a n g u l a t i o n o f the f l e x e d knee, and h i p f l e x i o n  are  t h e motions used t o p r e s s u r e the i n s i d e edge o f t h e d o w n h i l l ski  ( M a c i n t y r e and Matheson, 1988).  t h e s k i t o f l e x and carve an a r c .  This pressure  causes  Upon c o m p l e t i o n  of the  a r c t h e s k i e r unweights , p i v o t s toward a new p r e s s u r e s t h e i n s i d e edge of the new another  direction,  and  downhill s k i creating  arc.  W h i l e t h e motions of the a n k l e , knee, and h i p d u r i n g a s k i t u r n can be e a s i l y observed,  the motion o f the f o o t  w i t h i n t h e s k i boot i s c o m p l e t e l y hidden  from v i e w .  During  t h e s k i t u r n t h e f o o t i s s u b j e c t e d t o a p a t t e r n o f weight s h i f t i n g s i m i l a r t o t h a t of normal g a i t Matheson, 1988).  The  (Macintyre  o f t e n documented w a l k i n g and  p a t t e r n of s u p i n a t i o n - p r o n a t i o n - r e s u p i n a t i o n occurs  and running during  t h e s k i t u r n as t h e s k i e r ' s weight s h i f t s from t h e h e e l t o t h e f o r e f o o t ( M a c i n t y r e and Matheson, 1988). 8  Because o f the  l o c k i n g e f f e c t of the buckled  s k i boot there  i s no  s t r i k e or t o e - o f f experienced  (Macintyre  Matheson,  1988).  Using transducers  and  l o c a t e d i n the  footbed  o f a s k i b o o t , M e d o f f e t a l . (1985a) f o u n d t h e through a r e p e t i t i v e pattern thrust,  f o l l o w e d by  heel  and  part  of the  radius  than that  with  a p u s h - o f f on t h e  I n a d d i t i o n i t was  observed during  long  radius  go a  heel  the  forward  observed that  showed a more r a p i d ,  heel  tongue  foot to  of motion beginning  finally  slalom type turns  pattern  and  an e v e n d i s t r i b u t i o n o f f o r c e s on  f o r e f o o t , and foot.  true  short  inconsistent turns  (Medoff  et a l . , 1985a). The  forces  involved  i n causing  t u r n are t r a n s f e r r e d from the the  ski  being to the link is  skier  of v i t a l  as p o s s i b l e eversion This there  the  importance t h a t the  to i n i t i a t e  subtle action w i l l  not  f o r c e of the  as t h e r e  has  been l i t t l e  the boot d u r i n g is difficult plastic  due  the  motion.  to the  shell  action i s lost o r no  and  contact  as  i s a subtle  f o o t and  the  up  main  example, the  t r a n s f e r r e d to the  i s t o o much room b e t w e e n t h e the  For  are  such i t  f o o t t o b o o t f i t be  a s k i turn  be  as  to  back  boot i s the  r e a c t i o n , and  (Medoff et a l , 1985a).  required  same t i m e f o r c e s  The  a  s k i boots  snow t h r o u g h t h e b o o t and  s y s t e m o f a c t i o n and  Instead,  rigid  At  (Medoff et a l , 1985a).  in this  s k i to arc during  s k i e r through the  (Medoff et a l , 1985a).  t r a n s f e r r e d from the  the  close ankle  motion.  ski i f  boot.  i n s i d e of the  between the  boot  foot  and  Exaggeration of such a motion  limitations  of motion created  t h i c k foam l i n e r 9  of the  by  s k i boot.  the  Likewise,  c o m p e n s a t i o n f o r a p o o r f i t by  the  b o o t s can  the  foot  disrupt  the  tightly  t r a n s m i s s i o n of  into a pronated p o s i t i o n  buckling  forces  by  ( M a c i n t y r e and  locking  Matheson,  1988).  L o w e r L i m b A l i g n m e n t and All  Skiing  skiing s k i l l s originate  p o s i t i o n which requires  the  from a n e u t r a l  skier to  r i d e on  t h e i r s k i simultaneously while in a natural position either  i s referred  of the  to  c a t c h i n g an  pivoting  successfully.  that  riding a flat  he  edge on  tested  the  their natural  Subotnick to e x h i b i t  stance.  a d v e r s e l y a f f e c t the s k i are  tibia  or  an  varus  boot c u f f  skis.  position.  The  knees w i l l  Initiating  v a r u s , and  of  from  the which  adjusting can  i s set  foot  on  the  skiing.  through the  s t a n d on  c o n s e q u e n t l y be  the  in a  from t h i s p o s i t i o n 10  varus. of  effects  of  Varus boot  p e r p e n d i c u l a r to the  vara w i l l  a turn  a  1979).  (1988) o u t l i n e d and  rearfoot  to three degrees  is transferred  skier with t i b i a  p r e v e n t them  s k i without  (James,  tibia  the  I f the  the  of a s k i e r to p r o p e r l y r i d e  Matheson  tibia  the  on  lower limb alignments  forefoot  alignment of the  base the  This  Riding  (1982) f o u n d 80%  a v e r a g e o f two  v a r u s a l i g n m e n t s of the  ski.  ski.  of  most common a l i g n m e n t s w h i c h  ability  subtalar  M a c i n t y r e and  The  vara,  Most p e o p l e e x h i b i t rearfoot  stance.  snow, and  p r e v e n t e d them from r i d i n g a f l a t  flat  b o t h edges  s k i ' s edges w h i l e g l i d i n g w i l l p r e d i s p o s e  skier to  skiers  as  glide  to boot  outside  varus is  of  difficult.  Because they are l o c k e d onto t h e i r o u t s i d e  edges, s k i e r s w i t h t h i s c o n d i t i o n t e n d t o jump from one t o t h e next i n s t e a d of c a r v i n g l i n k e d t u r n s .  turn  A l i g n i n g the  boot c u f f t o t h e angle of the t i b i a w h i l e the base o f the boot remains l e v e l a l l o w s the s k i e r t o r i d e a f l a t s k i w h i l e i n a n a t u r a l stance. A more d i f f i c u l t  c o n d i t i o n to c o n t r o l w i t h i n the s k i  boot i s a v a r u s alignment not appear u n t i l position. pronate  o f the f o o t .  The  condition  may  the s k i e r assumes a f u n c t i o n a l s k i i n g  D u r i n g weight b e a r i n g the v a r u s a l i g n e d f o o t w i l l  e x c e s s i v e l y . ( M a c i n t y r e and Matheson,  P r o n a t i o n i s a combination dorsiflexion.  1988)  of ankle e v e r s i o n , abduction,  During running pronation i s necessary  d e c r e a s i n g the f o r c e s e x p e r i e n c e d by the l e g , but  for  excessive  p r o n a t i o n causes an i n c r e a s e d amount o f t i b i a l r o t a t i o n a decreased  ability  and  and  t o reduce shock (Nigg, 1986).  C o n t r i b u t i n g t o p r o n a t i o n i n s k i e r s i s the a n k l e e v e r s i o n necessary itself.  for turn i n i t i a t i o n  as w e l l as the s k i boot  A t i g h t l y b u c k l e d boot i s b e l i e v e d t o f l a t t e n  the  l o n g i t u d i n a l a r c h , p r e v e n t i n g the f o o t from s u p i n a t i n g a f t e r unweighting  ( M a c i n t y r e and Matheson, 1988).  E x c e s s i v e p r o n a t i o n can p l a c e the s k i e r i n a p o s i t i o n c h a r a c t e r i z e d by the s k i t i p s p o i n t i n g outward and the knees p o i n t i n g inward. technique  T h i s p o s i t i o n r e s u l t s i n poor s k i i n g  and p a i n .  The extreme v a l g u s p o s i t i o n o f t h e knee  r e q u i r e d f o r t u r n i n g from t h i s p o s i t i o n causes t h e upper body and the h i p s t o r o t a t e i n t o the h i l l . 11  Instead of  carving,  the  s k i e r banks t h e i r t u r n s .  This r e s u l t s  in a  s h i f t i n g of the  center of g r a v i t y o u t s i d e of the base  support  skier  and  the  falls uphill.  P a i n may  result  of from  the extreme r o t a t i o n of the t i b i a  a t t h e knee w h i c h  accompanies e x c e s s i v e p r o n a t i o n .  Attempts to s t a b i l i z e  f o o t by cold,  c u r l i n g the toes  cramped f e e t .  Orthotics,  ( M a c i n t y r e and  F o o t b e d s , and  I t has  or t i g h t e n i n g the b u c k l e s  associated with pronation  t h a t the i s the  i n a n e u t r a l p o s i t i o n w i t h i n the  shoes  to  1988)  s o l u t i o n to the  problems  s t a b i l i z a t i o n of the s k i boot  (Macintyre  foot and  R u n n i n g s t u d i e s h a v e shown o r t h o t i c s t o  r e d u c e r e a r f o o t m o t i o n and running  leads  Skiing  been suggested  Matheson, 1988).  Matheson,  the  o v e r a l l p r o n a t i o n when u s e d i n  ( C l a r k e et a l , 1984).  There are  various  t h e o r i e s as t o t h e m e c h a n i s m by w h i c h o r t h o t i c s r e d u c e r e a r f o o t m o t i o n and  pronation.  S m i t h e t a l . (1983)  running  shoe o r t h o t i c s t o - r e d u c e  running  and  suggested  found  calcaneal eversion  t h a t t h i s d e c r e a s e may  be  during  a  s i g n i f i c a n t m e c h a n i s m f o r t h e r e d u c t i o n o f symptoms by orthotics. l a t e r and  B a t e s e t a l . (1979) f o u n d t h a t p r o n a t i o n ended sooner d u r i n g r u n n i n g  than without  t h e use  of o r t h o t i c s .  s t u d i e s Bates et al.(1979) f o u n d t h a t t h e use  and  Nigg  o f o r t h o t i c s by  the mechanics of the  lower  trials  with orthotics  In i n d e p e n d e n t l y and  began  Leuthi  run  (1980)  i n j u r e d runners  both  altered  e x t r e m i t y enough t o d e c r e a s e  amount o f p r o n a t i o n e x p e r i e n c e d  to levels  similar to  the  those  e x p e r i e n c e d by non 1986).  Another  injured  runners  ( S t a c o f f and  study found a decrease i n r e a r f o o t  w i t h the increased height of the o r t h o t i c The  Leuthi,  manufacturers of s k i boot  motion  (Cavanagh,  1980) .  footbeds claim that  their  p r o d u c t s can c o n t r o l p r o n a t i o n i n s i d e o f a s k i boot s i m i l a r l y to the control orthotics during running.  found t o o c c u r w i t h t h e use In a d d i t i o n t h e i r  literature  maintains t h a t c o n t r o l l i n g the e x c e s s i v e motions w i t h p r o n a t i o n c a n r e d u c e p a i n and edge c o n t r o l  fatigue,  ( P e t e r s o n Tech. Manual,  of  and  Superfeet  associated increase  Tech.  Manual).  Footbed  Construction.  The p r i m a r y f u n c t i o n o f any biomechanical c o n t r o l of the foot Taunton,  1985).  S k i boot  orthotic  footbed i s the  (McKenzie, Clement,  footbed manufacturers agree  and with  sports medicine p r a c t i t i o n e r s that the i d e a l p o s i t i o n of the f o o t i s one  i n which the s u b t a l a r  (McKenzie, Clement, differ  i s neutral  1985).  Manufacturers  on t h e i r m e t h o d s o f c r e a t i n g a f o o t b e d i n w h i c h  subtalar this  and T a u n t o n ,  joint  joint  i s held neutral.  The  the  footbeds u t i l i z e d i n  s t u d y were molded w i t h t h e s u b j e c t i n a s e a t e d p o s i t i o n  w i t h no w e i g h t b e i n g p l a c e d on t h e f e e t Manual).  The  ( S u p e r f e e t Tech.  foot i s maintained i n a neutral  position  t h r o u g h o u t t h e m o l d i n g p r o c e s s by t h e t e c h n i c i a n Tech. M a n u a l ) .  Other s k i boot  (Superfeet  f o o t b e d s are molded i n a  weight b e a r i n g p o s i t i o n with high density 13  foam p l a c e d u n d e r  the foot t o maintain a n e u t r a l p o s i t i o n Manual).  ( P e t e r s o n Tech.  There are no data a v a i l a b l e comparing the  s u c c e s s e s o f t h e s e two t e c h n i q u e s i n c r e a t i n g a f o o t b e d w h i c h can m a i n t a i n the f o o t i n a n e u t r a l p o s i t i o n . Footbed m a t e r i a l s v a r y w i t h m a n u f a c t u r e r .  The  footbeds  u t i l i z e d i n t h i s study were made from cork w i t h a n o n - s l i p , b r e a t h a b l e t o p cover  (Superfeet Tech. Manual).  chosen f o r a f o o t b e d must be f i r m .  The m a t e r i a l  A f l e x i b l e footbed  can  c o l l a p s e under the p r e s s u r e s a s s o c i a t e d w i t h the s k i t u r n ( S u p e r f e e t Tech. Manual).  The  f o o t b e d must a l s o w i t h s t a n d  t h e p r e s s u r e s e x e r t e d by the b u c k l i n g of the b o o t s . Running shoe o r t h o t i c s t y p i c a l l y end  j u s t a f t e r the  m e t a t a r s a l heads t o a l l o w f o r f l e x i b i l i t y at the t o e s reduce the chance of cramping Taunton, 1985.).  (McKenzie,  Clement,  and  and  T h i s i s j u s t i f i a b l e i n such o r t h o t i c s as  i t has been shown t h a t a l l the b i o m e c h a n i c a l  control that  t a k e s p l a c e does so from the h e e l t o i m m e d i a t e l y t h e m e t a t a r s a l heads (McKenzie,  proximal to  Clement, and Taunton, 1985).  S k i boot o r t h o t i c s are f u l l l e n g t h as the  manufacturers  b e l i e v e t h a t t h i s i n c r e a s e s the s t a b i l i t y o f f e r e d by  the  f o o t b e d w h i l e b a l a n c i n g the o v e r a l l support and f u n c t i o n ( S u p e r f e e t Tech. Manual).  No d a t a were a v a i l a b l e t o  i n d i c a t e t h e mechanism o f c o n t r o l i n any brand o f s k i boot footbed. S t u d i e s have found s i g n i f i c a n t d i f f e r e n c e s between the b i o m e c h a n i c a l parameters of i n d i v i d u a l s ' r i g h t and l e f t s u g g e s t i n g t h a t t h e r e i s a need t o c o n t r o l each f o o t 14  legs  individually  (McKenzie, Clement, and Taunton 1985). A l l  custom molded footbeds m o l d i n g one f o o t b e d the  same i d e o l o g y  d e a l w i t h each f o o t  at a time.  study  and as such a n a l y s e s  a t each f o o t as a s e p a r a t e subject.  This  This allowed  separately, operated  under  were d e s i g n e d  v a r i a b l e belonging  t o look  t o one  f o r the i n v e s t i g a t i o n of within  s u b j e c t v a r i a b i l i t y b e t w e e n f e e t as w e l l a s b e t w e e n t y p e o f insole.  Pain  Analysis Unfortunately,  experience. to define. sensations  pain  Although  i s a p a r t o f many p e o p l e ' s  common, p a i n i s a d i f f i c u l t  subject's reaction to that stimuli  stimuli  i n response t o p a i n f u l s t i m u l i has been  background, previous  training,  (Medoff e t a l , 1985b).  the  of a f a l l ,  relates to this  collision,  study,  cultural  and t h e i n f l u e n c e o f  suggestion  buckled  as w e l l as t h e  (Medoff e t a l , 1985b).  a t t r i b u t e d t o f a c t o r s s u c h as age , g e n d e r ,  result  parameter  I t i s a c o m p l e x phenomenon e n c o m p a s s i n g t h e e v o k e d by t i s s u e - d a m a g i n g  Variability  skiing  Pain  i n skiing  cold injury,  improperly  i s often  o r as i t  f i t t e d boots or t i g h t l y  boots.  R a t i n g p a i n u s i n g d e s c r i p t i v e s c a l e s c a n be a p p r o a c h e d f r o m two d i r e c t i o n s .  Sensory s c a l e s u t i l i z e words t h a t  r e l a t e t o q u a l i t y and i n t e n s i t y moderate  (Medoff e t a l , 1985b).  words s u c h as u n p l e a s a n t  s u c h a s t h e w o r d s weak a n d A f f e c t i v e pain  and d i s t r e s s i n g ,  s c a l e s use  which r e l a t e t o  t h e m o t i v a t i o n a l and e m o t i o n a l v a r i a b l e s a s s o c i a t e d w i t h pain experience s c a l e was  (Medoff et a l , 1985b).  The  the  s e n s o r y t y p e of  chosen f o r t h i s study as i t u t i l i z e s terms which  are more a p p r o p r i a t e  f o r d e s c r i b i n g the e f f e c t i v e n e s s of  footbeds. V i s u a l analogue s c a l e s have been shown t o  be  s a t i s f a c t o r y measurement t o o l s i n the assessment of p a i n (Huskisson,  1983).  According  to Huskisson  (1983) the  g r e a t e s t advantage of the v i s u a l analogue s c a l e i s the u n i f o r m i t y of d i s t r i b u t i o n of r e s u l t s .  The  scale  may  c o n s i s t o f e i t h e r a v e r t i c a l or h o r i z o n t a l l i n e w i t h  stops  at b o t h ends at r i g h t a n g l e s t o the l i n e  1983).  (Huskisson,  Both s c a l e s have proven s a t i s f a c t o r y a l t h o u g h i t i s recommended t h a t o n l y one o f any  one  of the two be used over the  study i n order to maintain  H u s k i s s o n , 1979).  The  v e r t i c a l s c a l e has  e r r o r the a n g l e at which i t i s viewed 1981).  consistency  course  (Scott  and  as a s o u r c e o f  (Dixon and B i r d ,  V i e w i n g angle does not a f f e c t the h o r i z o n t a l s c a l e  w h i c h was  t h e r e f o r e chosen f o r use  i n t h i s study.  Further  s o u r c e s of e r r o r encountered when u s i n g r a t i n g s c a l e s can a r e s u l t of inadequate i n s t r u c t i o n s and (Dixon and B i r d , 1981).  subject  Some r e s e a r c h e r s  compliancy  feel that r a t i n g  s c a l e s r e f l e c t what the s u b j e c t b e l i e v e s they ought t o r a t h e r t h a n t h e i r t r u e f e e l i n g s (Dixon and B i r d , 1981). h o r i z o n t a l v i s u a l analogue s c a l e was  feel The  u t i l i z e d i n t h i s study  f o r the purpose of r a t i n g edge c o n t r o l and as t h e t r a d i t i o n a l use as a p a i n s c a l e . 16  be  f a t i g u e as w e l l  T h i s was  done i n an  e f f o r t t o m a i n t a i n c o n s i s t e n c y w h i l e m i n i m i z i n g the amount of i n s t r u c t i o n s r e q u i r e d .  17  Chapter  3  PROCEDURES  The p r i m a r y p u r p o s e  of t h i s  s t u d y was  q u a n t i t a t i v e l y t h e e f f e c t i v e n e s s o f custom footbeds i n c o n t r o l l i n g the motions pronation.  The  second purpose  to  determine  molded s k i boot  associated  o f t h e s t u d y was  with to  quantify  the subjective experiences of s k i e r s i n a c o n t r o l l e d  study.  Subjects The adult  study u t i l i z e d  a s u b j e c t group  o f 15 a d v a n c e d  level  s k i e r s r e c r u i t e d t h r o u g h t h e use o f p o s t e r s d i s p l a y e d  at a major  university,  s k i shops,  and l o c a l  ski hills.  s u b j e c t s a l l d i s p l a y e d a minimum o f t h r e e d e g r e e s subtalar varus i n both feet.  No  s u b j e c t had  e x p e r i e n c e s k i i n g on t h e b r a n d o f c u s t o m i n the study.  Prior to testing,  The  of  prior  molded f o o t b e d used  e a c h s u b j e c t was  informed  as t o t h e n a t u r e o f t h e s t u d y a n d g a v e w r i t t e n c o n s e n t  to  participate. The  l a b o r a t o r y s e c t i o n o f t h e s t u d y was  o n l y 13 o u t o f t h e o r i g i n a l  conducted u s i n g  g r o u p o f s u b j e c t s due  to  attrition.  Research The  Design independent  variables  the s k i i n g portions of t h i s i n s o l e s and t h e custom  f o r both the laboratory  s t u d y were t h e non-custom  molded f o o t b e d s . 18  The  laboratory  and  p o r t i o n of the  research  feet, while the  the  the  angle  at the  s k i i n g p o r t i o n of the  s h o r t r a d i u s and for  also looked  long radius turns.  l a b o r a t o r y p o r t i o n of the  r i g h t and  study The  study  controlled for  dependent v a r i a b l e s were n a v i c u l a r d r o p ,  of i n s e r t i o n of the A c h i l l e s tendon at  calcaneus  ( r e a r f o o t a n g l e ) , and  the  left  the  alignment of the  tibial  t u b e r o s i t y w i t h r e s p e c t t o t h e mid-seam o f t h e b o o t ' s  toe  piece.  the  T h e s e v a r i a b l e s w e r e c h o s e n as t h e y  events associated with pronation in  the  laboratory.  p o r t i o n of the level  The  study  were e a s i l y  monitored  dependent v a r i a b l e s f o r the  were l e v e l o f p e r c e i v e d  of perceived pain,  race  and  reflected  l e v e l of perceived  edge  skiing  control,  fatigue,  and  results. The  study  was  designed  as a t e s t / r e t e s t  situation  each subject r e p e a t i n g the  same p r o c e d u r e s w i t h b o t h  custom molded footbeds  the non-custom i n s o l e s i n a  random  Section  Initial  A s s e s s m e n t . A l l s u b j e c t s were a s s e s s e d  subtalar varus, one  the  order.  Laboratory  by  and  with  forefoot varus,  and  for  functional hypermobility  i n v e s t i g a t o r f o l l o w i n g the p r o t o c o l s o u t l i n e d i n  A p p e n d i x A. were a s s e s s e d  Forefoot  v a r u s and  functional hypermobility  only f o r t h e i r presence.  measured t o the n e a r e s t  d e g r e e and  19  Subtalar varus  recorded  i n Appendix  was C.  F o o t b e d P r e p a r a t i o n . Custom molded f o o t b e d s brand) were p r e p a r e d technicians Ski buckle  (Superfeet  f o r e a c h s u b j e c t b y one o f t w o  f o l l o w i n g t h e p r o t o c o l o u t l i n e d i n A p p e n d i x B.  Boot P r e p a r a t i o n . A t o t a l  overlap design  s k i boots,  of five p a i r s of four  women's s i z e s 6.5, 7.5, a n d  men's s i z e s 8.5, 1 0 . 5 , 11.5 w e r e u s e d i n t h e l a b o r a t o r y section of this  study.  A l l o f t h e b o o t s w e r e o f t h e same  make a n d c o m p a r a b l e m o d e l .  T h e s e b o o t s w e r e c u t away a t  the  r e a r and medial  sides t o allow f o rthe observation of  the  i n s e r t i o n o f the A c h i l l e s at the calcaneus  navicular tubercle respectively.  and t h e  These a r e a s o f t h e boot  s h e l l w e r e g r o u n d down u s i n g a b e l t g r i n d e r a n d c u t o p e n with a jigsaw.  Edges were smoothed and f i n i s h e d by k n i f e .  The b o o t l i n e r s w e r e t h e n p l a c e d the  i n s i d e o f t h e s h e l l s and  o u t l i n e s o f t h e windows w e r e t r a c e d .  r e m o v e d , c u t open b y k n i f e , shell.  and p l a c e d back i n t o t h e boot  A l l b o o t s w e r e c h e c k e d on t e s t  c l e a r view of t h e required  L i n e r s were  subjects t o ensure a  landmarks.  M a r k e r s w e r e p l a c e d a l o n g t h e mid-seam o f t h e t o e a n d heel pieces medial as  a r c h window a s shown i n F i g u r e  standard Ski  rear,  o f t h e b o o t as w e l l as t o t h e f r o n t o f t h e  points of reference  1.  forlater  These marks  serve  analyses.  b o o t s w e r e l a b e l e d f o r s i z e a n d f o o t on t h e f r o n t ,  and m e d i a l  digitizing.  s i d e f o r easy i d e n t i f i c a t i o n  As w e l l ,  boot d u r i n g t h e i r  during  e a c h s u b j e c t was i d e n t i f i e d on t h e  trials.  20  Figure  l a . M e d i a l window o f s k i b o o t e x p o s i n g t h e  navicular  Figure  tubercle  \  \  /  I  l b . R e a r window o f s k i b o o t e x p o s i n g t h e  insertion of the A c h i l l e s  Figure  •  at the calcaneus.  l c . Front view o f s k i boot w i t h  tuberosity.  21  tibial  Data C o l l e c t i o n .  The s u b j e c t r e m o v e d b o t h s o c k s a n d  s h o e s a n d was f i t t e d f o r t e s t provided and  s k i boots using a s i z e r  b y t h e b o o t company.  A l l s u b j e c t s were  m a r k e d on b o t h l e g s b y one i n d i v i d u a l .  palpated  The f o l l o w i n g  l a n d m a r k s w e r e m a r k e d : a . N a v i c u l a r t u b e r c l e ; b . The attachment o f t h e A c h i l l e s tendon t o t h e calcaneus, 1.5 cm d i s t a l  t o t h e attachment s i t e ,  a point  a n d t w o more p o i n t s  spaced between t h e t o p o f t h e s k i boot and t h e p o p l i t e a l s p a c e on t h e m i d l i n e o f t h e l e g a s (1979); The  c. M i d p o i n t  o u t l i n e d i n James  of the t i b i a l tuberosity.  s u b j e c t p u t on t h e r i g h t b o o t w i t h t h e n o n c u s t o m  i n s o l e and b u c k l e d  t h e boot as t h e y  would f o r s k i i n g . A l l  w i n d o w s w e r e c h e c k e d f o r an u n o b s t r u c t e d landmarks. Kistler  The s u b j e c t t h e n s t o o d  view o f t h e  on a f l u s h m o u n t e d  M o d e l 9261-A f o r c e p l a t f o r m s u c h t h a t t h e mid-seam  o f t h e f r o n t and r e a r o f t h e b o o t were a l i g n e d w i t h t h e y a x i s o f t h e p l a t f o r m and t h e m e t a t a r s a l x axis.  An o s c i l l o s c o p e was u s e d t o d e t e c t t h e d i s p l a c e m e n t  of t h e center this  heads c r o s s e d t h e  of pressure  into a single vector.  on t h e f o r c e p l a t f o r m a n d c o n v e r t When t h e c e n t e r  of pressure  l o c a t e d on t h e x a x i s o f t h e p l a t f o r m , t h e l i n e r e p r e s e n t i n g m o t i o n i n t h e 'y' p l a n e scope's zero  line.  When t h e c e n t e r  the  r e a r f o o t t h e 'y' p l a n e  the  zero  line  line.  22  was  on t h e s c o p e  was a l i g n e d w i t h t h e of pressure  i s moved t o  o f t h e scope dropped below  The Ski  subject  the  load.  rear of the  the metatarsal  line. this  the  The  This  right  weighting  of pressure  T h i s p o s i t i o n was  foot  only.  and  was  transferred  deemed  "end  position"  end  •y  1  i s confirmed  plane  scope.  actions of unweighting  s u c c e s s f u l l y completed of the  t r i a l s u s i n g 35mm s l i d e  subject repeated custom footbed, and  the  left  was  placed beside  left  of pressure  was  the  rearfoot.  right  custom footbed.  The  foot with  custom A 30  analyses.  23  the  insole, cm  ruler  subject during a l l photographs to  as a s c a l i n g r o d i n l a t e r  end  The  neutral.  f o o t u s i n g t h e non  foot using the  and  then photographed i n a  the p r o t o c o l using the the  the  film.  f r o n t lower  l e g was  the  start  The  i n which center  and  subject  l i n e s on  p h o t o g r a p h e d f i r s t , f o l l o w e d by t h e  position  start  The  n a v i c u l a r was subject's  in  trials.  p r a c t i s e t r i a l s , p h o t o g r a p h s were t a k e n p o s i t i o n s o v e r two  zero  s t a r t p o s i t i o n t o t h e end p o s i t i o n  T h i s t o o k a mean o f 13.07 s u b j e c t had  the  and  Both the  c o u l d c o n s i s t e n t l y m a t c h up t h e  When t h e  to  the  p o s i t i o n s were c h o s e n f o r use  as t h e y m i m i c t h e  p r a c t i s e d moving from the  on  l i n e w i t h the  during a carved p a r a l l e l t u r n .  they  the  heel contact with  p o s i t i o n s were h e l d f o r f i v e seconds each.  until  without  subject then t r a n s f e r r e d pressure  alignment of the  These s t a r t study  center  heads w h i l e m a i n t a i n i n g  force platform. s c o p e by  The  foot.  "start position".  end  on t h e  p o l e s were used t o a s s i s t , i n m a i n t a i n i n g b a l a n c e  supporting the to  i n i t i a l l y stood  act  D a t a A n a l y s i s . P r o c e s s e d s l i d e s were p r o j e c t e d white paper taped t o a w a l l .  onto  Images o f t h e m a r k e d p o i n t s  on  b o t h t h e s u b j e c t and t h e b o o t were t r a c e d onto t h e p a p e r . g r i d was  c o n s t r u c t e d on e a c h i n d i v i d u a l d a t a p a g e u s i n g t h e  boot landmark landmark  as t h e o r i g i n .  The d i s t a n c e o f t h e a n a t o m i c a l  f r o m t h e x and y a x e s was  measured  a s e t o f c o o r d i n a t e s . A n g l e s were measured S c a l i n g f a c t o r s were c a l c u l a t e d the  and r e c o r d e d as by  protractor.  f o r each frame by  measuring  image o f t h e s c a l i n g r o d . R e a l l e n g t h c o o r d i n a t e s  c a l c u l a t e d by image l e n g t h / s c a l i n g f a c t o r . start  A  and end p o s i t i o n s  were  Differences i n  f o r a l l measurements were  calculated  and r e c o r d e d . S t a t i s t i c a l A n a l y s i s . L a b o r a t o r y d a t a were e n t e r e d i n t o the  computer  program  L o t u s 1-2-3  c a l c u l a t e d a c r o s s t h e two t r i a l s variable. program, levels at  f o r each  s u b j e c t i n each  A v e r a g e s were t r a n s f e r r e d t o a n o t h e r S y s t a t f o r a n a l y s i s as two  computer  f a c t o r models  with  f o r e a c h f a c t o r and r e p e a t e d m e a s u r e s on e a c h  a s i g n i f i c a n c e o f 0.05.  H a r v a r d G r a p h i c s computer  Skiing  where a v e r a g e s were  level  Graphs were p r o d u c e d u s i n g t h e program.  Section  Data C o l l e c t i o n . Levels of p e r c e i v e d p a i n ,  fatigue,  edge c o n t r o l w e r e a s s e s s e d u s i n g h o r i z o n t a l v i s u a l scales.  two  E a c h s c a l e c o n s i s t e d o f 10cm  s t o p s a t b o t h ends, a t r i g h t were l a b e l e d  and  analogue  horizontal  line  angles to the l i n e .  The  with stops  "none" and " s e v e r e " f o r b o t h t h e p a i n and t h e 24  f a t i g u e s c a l e s a n d "none" a n d " t o t a l " scales.  The s u b j e c t s w e r e a s k e d t o make a mark on t h e l i n e s  at t h e p o i n t which they experiences. simple  f o r t h e edge c o n t r o l  felt  corresponded t o t h e i r  The v i s u a l a n a l o g u e s c a l e was c h o s e n a s i t was  enough t o be a d m i n i s t e r e d  on t h e h i l l  immediately  f o l l o w i n g each s k i r u n . On-hill s k i day.  s k i t e s t i n g took p l a c e over t h e course  Subjects  s k i e d i n t h e i r own s k i b o o t s .  o f one  A d r a w was  made t o r a n d o m l y a s s i g n e a c h s u b j e c t t o one o f t w o t e s t g r o u p s . One g r o u p s k i e d t h e f i r s t  h a l f o f t h e day u s i n g non  custom i n s o l e s w h i l e t h e other group used t h e custom molded footbeds.  Although  t h e s u b j e c t s were n o t i n f o r m e d  w h i c h o f t h e two groups t h e y differences b l i n d study All  had been a s s i g n e d , t h e  i n f e e l o f t h e two t y p e s  o f i n s o l e s make a t r u l y  improbable.  s u b j e c t s s p e n t two h o u r s f r e e s k i i n g t o a d a p t t o  w h i c h e v e r i n s o l e t h e y were u s i n g . gathered  as t o  A f t e r two h o u r s t h e group  f o r a s e t o f assessment runs.  s k i e d on i n t e r m e d i a t e  These r u n s were  t e r r a i n c o n s i s t i n g of a gradual  g r o o m e d c o n d i t i o n s , a n d o n l y a few s m a l l bumps.  slope,  The  s u b j e c t s s k i e d one r u n u s i n g s h o r t r a d i u s t u r n s , a n d one r u n using long radius turns.  F o l l o w i n g each o f these  subjects completed a v i s u a l perceived  analogue s c a l e t o assess  edge c o n t r o l d u r i n g t h e r u n .  b o t h r u n s t h e s u b j e c t s s k i e d two t i m e d race course.  A l l times  runs t h e  were r e c o r d e d .  runs each s u b j e c t completed v i s u a l 25  After  completing  runs each through a Following the timed  analogue s c a l e s f o r both  pain  and f a t i g u e  l e v e l s a t t h e end o f t h e s e s s i o n .  groups t h e n changed a s s i g n m e n t s and r e p e a t e d t h e with  t h e i r new  V i s u a l analogue scales  from the l e f t  distances  were r e c o r d e d . Race t i m e s were  transferred  one f a c t o r m o d e l s w i t h each l e v e l using  where  i n each v a r i a b l e .  into the Systat  mark a n d a l l  recorded.  S k i i n g d a t a were e n t e r e d i n t o t h e  c o m p u t e r p r o g r a m L o t u s 1-2-3 each subject  were measured f o r  stop t o the subject's  Statistical Analysis.  for  protocol  footbed/insole.  Data A n a l y s i s . distance  The  a v e r a g e s were  calculated  A v e r a g e s were  computer program f o r a n a l y s i s  two l e v e l s a n d r e p e a t e d m e a s u r e s  a t a s i g n i f i c a n c e o f 0.05.  on  Graphs were p r o d u c e d  H a r v a r d G r a p h i c s computer program.  26  as  Chapter 4 RESULTS AND DISCUSSION  Description The 15  of Subjects  subject  group u t i l i z e d  advanced l e v e l  adult  i n this  study c o n s i s t e d of  s k i e r s who e x h i b i t e d more t h a n  degrees o f s u b t a l a r varus i n each f o o t . A p p e n d i x C, t h e mean a g e , h e i g h t , g r o u p was 25.13 + 3.96 y e a r s , 7.25 k g r e s p e c t i v e l y .  three  As i n d i c a t e d i n  a n d mass o f t h e s u b j e c t  171.17 + 5 . 6 9  cm, a n d 70.47 +  The g r o u p e x h i b i t e d an a v e r a g e o f 5.6  + 1.5 d e g r e e s o f s u b t a l a r v a r u s i n t h e r i g h t f o o t , a n d 4.9 +_ 1.2 d e g r e e s o f s u b t a l a r v a r u s i n t h e l e f t w h i c h was n o t s t a t i s t i c a l l y  foot, a difference  s i g n i f i c a n t (p=0.156).  The  a v e r a g e number o f y e a r s o f s k i i n g e x p e r i e n c e was 15.47 +_ 3.15 y e a r s .  A l l subjects  of t h e study.  The the  rearfoot  Section  tuberosity  from t h e c e n t e r  with pronation  displacement of  l i n e o f t h e b o o t , and  a n d c o u l d be e a s i l y m o n i t o r e d i n  laboratory. Navicular  the  section.  a n g l e were m o n i t o r e d as t h e y r e f l e c t e d t h e e v e n t s  associated the  participated i n the laboratory  position of the navicular tubercle,  tibial  section  A s u b g r o u p c o n s i s t i n g o f 13 o f t h e o r i g i n a l  group o f s u b j e c t s  Laboratory  participated i n the skiing  foot during  D r o p . As w e i g h t i s t r a n s f e r r e d f o r w a r d  along  t h e c a r v i n g phase o f t h e s k i t u r n t h e  navicular tubercle  t y p i c a l l y moves b o t h f o r w a r d a n d downward 27  in the  r e l a t i o n to i t s position during turn.  This  t h e unweighted phase o f  n a v i c u l a r motion, r e f e r e d t o i n t h i s  as n a v i c u l a r d r o p , i s s i m i l a r t o t h a t e x p e r i e n c e d w a l k i n g a s t h e f o o t moves f r o m t h e h e e l to the point  just prior to toe-off.  study  during  s t r i k e phase through  Navicular  drop  along  b o t h t h e x a n d y a x e s o f t h e s a g g i t a l p l a n was c a l c u l a t e d for  each s u b j e c t ' s  trials.  r i g h t and l e f t  the  over a t o t a l  Two t r i a l s w e r e p e r f o r m e d u s i n g  i n s o l e s and two t r i a l s Location  foot  of four  t h e non custom  used t h e custom molded  footbeds.  o f t h e n a v i c u l a r t u b e r c l e was d e t e r m i n e d a t b o t h  s t a r t and end p o s i t i o n s as o u t l i n e d i n t h e p r o c e d u r e s  section. The and  location of the navicular tubercle  on b o t h t h e x  y axes f o r t h e s t a r t and end p o s i t i o n s u s i n g  both the  non-custom i n s o l e s and t h e custom molded footbeds a r e summarized i n F i g u r e s  2-3.  The n o n - c u s t o m i n s o l e s a r e  r e f e r r e d t o as "boot" and t h e custom molded i n s o l e s a r e shown a s " f o o t b e d " on a l l c h a r t s . In t h e s t a r t p o s i t i o n f o r b o t h t h e r i g h t and l e f t there  was 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 d i f f e r e n c e between t h e  location of the navicular tubercle  i n b o t h t h e x and y  d i r e c t i o n when c o m p a r i n g t h e b o o t t o t h e f o o t b e d . n a v i c u l a r was p o s i t i o n e d b o t h h i g h e r when t h e s u b j e c t standing  was s t a n d i n g  The  and f a r t h e r backward  on t h e f o o t b e d a s c o m p a r e d t o  on t h e n o n - c u s t o m i n s o l e .  attributed to the thickness the  feet  This  difference  c a n be  o f t h e f o o t b e d as compared t o  non-custom i n s o l e as w e l l as t o t h e r e a l i g n m e n t o f t h e 28  10.0  cm  i  SB vs SF sig., p • 0.034  EB vs EF sig., p • 0.000  START • i  END BOOT  E3  FOOTBED  Figure 2a. Navicular start/end positions, x dir., right foot  10.0  cm  i  SB vs SF sig., p • 0.000  EB vs EF sig., p • 0.000  START H  END BOOT  EZ3 FOOTBED  Figure 2b. Navicular start/end positions, x dir., left foot  SB - S t a r t B o o t EB - E n d B o o t  SF - S t a r t F o o t b e d EF - E n d F o o t b e d  29  10.0  cm  i  SB vs SF sig., p • 0.000  EB vs EF sig., p - 0.000  —  START • i  •  END BOOT  EZ2 FOOTBED  Figure 3a. Navicular start/end positions, y dir., right foot  10.0  cm  SB vs SF sig., p • 0.000  EB vs EF sig., p • 0.000  8.0  2,0  0.0  START •I  END BOOT  ¥22 FOOTBED  Figure 3b. Navicular start/end positions* y dir., left foot SB - S t a r t B o o t EB - E n d B o o t  SF - S t a r t F o o t b e d EF - E n d F o o t b e d  30  f o o t by t h e f o o t b e d .  T h e r e was a s i m i l a r s i g n i f i c a n c e when  c o m p a r i n g e n d p o s i t i o n s o f t h e n a v i c u l a r t u b e r c l e . The n a v i c u l a r was s i t u a t e d h i g h e r  and f a r t h e r back i n t h e boot  when t h e s u b j e c t was s t a n d i n g  i n t h e e n d p o s i t i o n on t h e  custom footbed  t h a n i t was when s t a n d i n g  i n t h e end p o s i t i o n  on t h e i n s o l e . Figures  4-5 show t h e r a n g e t h r o u g h w h i c h t h e n a v i c u l a r  t u b e r c l e moves when t h e s u b j e c t end  position.  This  from t h e s t a r t t o t h e  r a n g e was d e t e r m i n e d b y c a l c u l a t i n g t h e  d i f f e r e n c e s between t h e s t a r t navicular.  shifts  and end p o s i t i o n s o f t h e  There i s a s t a t i s t i c a l l y  significant  i n t h e amount o f n a v i c u l a r m o t i o n e x p e r i e n c e d two  types  of insoles.  significantly  The c u s t o m f o o t b e d s  l e s s forward  non-custom i n s o l e s .  difference  when u s i n g t h e  allowed  a n d downward m o t i o n t h a n d i d t h e  These f i n d i n g s i n d i c a t e t h a t t h e custom  i n s o l e s changed t h e p o s i t i o n o f t h e f o o t and r e d u c e d t h e amount o f m o t i o n e x p e r i e n c e d specifically the  i n s i d e o f the boot,  that n a v i c u l a r motion which i s a s s o c i a t e d  f l a t t e n i n g of the arch during  with  pronation.  I t was n o t e d t h a t one s u b j e c t d i s p l a y e d a  slight  b a c k w a r d a n d downward m o t i o n o f t h e l e f t n a v i c u l a r t u b e r c l e w h i l e u s i n g t h e non-custom i n s o l e .  One s t u d y  c o n d u c t e d by a  b o o t m a n u f a c t u r e r h a s shown t h i s t o be a somewhat common phenomena w i t h t h e u s e o f o v e r l a p d e s i g n b o o t s due t o slippage at the heel  (Walkhoff  a n d Baumann,  s u b j e c t d i s p l a y e d t h e more t y p i c a l m o t i o n when u s i n g t h e c u s t o m m o l d e d 31  forward  1987).  The  a n d downward  footbed.  1.00  R vs L not sig.; B vs F sig., p • 0.000  cm  0.80 0.60 0.40 0.20 0.00  LEFT  RIGHT H  BOOT  ¥ZA FOOTBED  Figure 4. Navicular motion in the x direction.  R - Right B - Boot  Foot  L - L e f t Foot F - Footbed  32  0.60  0.40  cm  R vs L not sig.;  B vs F sig., p • 0.000  H  0.20  0.00  LEFT  RIGHT H  EZ3 FOOTBED  BOOT  Figure 5. Navicular motion in the y direction.  R - Right Foot B - Boot  L - L e f t Foot F - Footbed  33  T h e r e was no 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 n a v i c u l a r motions group.  o f t h e r i g h t and l e f t  T h e r e was no s i g n i f i c a n t  feet of the subject  i n t e r a c t i o n between type o f  i n s o l e and f e e t . R e a r f o o t A n g l e . The a n g l e c r e a t e d b y t h e m i d l i n e o f t h e l o w e r l e g a s i t moves away f r o m t h e p e r p e n d i c u l a r was t a k e n as t h e r e a r f o o t a n g l e i n t h i s of  the rearfoot  i n the start  study.  Photographs  i n degrees  r e s u l t s comparing of  taken  and end p o s i t i o n s u s i n g b o t h  non-custom i n s o l e s and custom f o o t b e d s . expressed  were  These a n g l e s ,  a r e d i s p l a y e d i n F i g u r e 6.  The g r o u p  the rearfoot angle at the s t a r t  position  t h e non-custom i n s o l e s t o t h a t a t t h e s t a r t p o s i t i o n o f  the custom footbeds f o r t h e r i g h t difference.  A statistically  f o u n d when c o m p a r i n g  f o o t showed a  significant  s i g n i f i c a n t d i f f e r e n c e was  also  t h e r e a r f o o t angles a t t h e end  p o s i t i o n s o f t h e two t y p e s o f i n s o l e s .  In both cases t h e  a n g l e o f t h e r e a r f o o t was d e c r e a s e d when u s i n g t h e c u s t o m f o o t b e d s a s c o m p a r e d t o t h e a n g l e e x h i b i t e d when u s i n g t h e insoles.  The r e s u l t s w e r e t h e same f o r t h e l e f t  difference  about by t h e custom molded  footbeds.  N e i t h e r t h e non-custom i n s o l e n o r t h e custom a l l o w e d any s i g n i f i c a n t  footbed  c h a n g e i n a n g l e when m o v i n g f r o m t h e  s t a r t t o t h e end p o s i t i o n w i t h e i t h e r t h e boot  This  i n a n g l e s c a n be a t t r i b u t e d t o t h e c h a n g e i n f o o t  alignment brought  of  foot.  foot.  The  integrity  a t t h e r e a r may i n f l u e n c e t h e amount o f m o t i o n  e x p e r i e n c e d by t h e r e a r f o o t .  The r e s u l t s  34  indicate that  SB vs SF sig., p • 0.000; EB vs EF sig., p • 0.000 SB vs EB not sig.; SF vs EF not sig. 7.0  i  BOOT  FOOTBED •  START  1ZZ2-END  Figure 6a. Rearfoot angles at start and end, right foot.  SB vs SF sig., p • 0.000; EB vs EF sig., p • 0.000 SB vs EB not sig.; SF vs EF not sig.  7.0 | 6.0 -  BOOT  FOOTBED • i  START  E22 END  Figure 6b. Rearfoot angles at start and end, left foot.  SB - S t a r t B o o t EB - E n d B o o t  SF - S t a r t F o o t b e d EF - E n d F o o t b e d  35  while  n e i t h e r type of i n s o l e allows  motion, the  any  custom footbeds m a i n t a i n  c l o s e r to the perpendicular  significant  the  both at the  leg  rearfoot  significantly  start  and  at the  end  position. T h e r e was start  and  of the  end  a s i g n i f i c a n t d i f f e r e n c e found i n both p o s i t i o n s when c o m p a r i n g t h e  r i g h t foot to the  left  foot.  rearfoot  Although the  measurements o f s u b t a l a r v a r u s t a k e n d u r i n g  initial  screening  significant  hip alignments could help  which d i d e x i s t . research  This  to amplify  any  Taunton, 1985).  differences  This  separately.  T h e r e was  the  t y p e o f i n s o l e and T i b i a l Rotation.  Tibial  one  one  to the  tibial  f l o o r and  tubercle  passing  T h i s v a r i a b l e was  This p o s i t i o n placed  the  measured  each subject  on  l e g at a time with weight e q u a l l y d i s t r i b u t e d across  foot.  The  significant the  m e a s u r e d by  (x d i r e c t i o n ) o f t h e  lying perpendicular  p o s i t i o n only.  i n t e r a c t i o n between  r o t a t i o n was  t h r o u g h t h e midseam o f t h e b o o t . in  foot  feet.  h o r i z o n t a l displacement from a l i n e  feet  finding  concept of c r e a t i n g footbeds f o r each significant  in  left  supports the  no  knee  other  b i o m e c h a n i c a l p a r a m e t e r s when c o m p a r i n g r i g h t and ( M c K e n z i e , C l e m e n t , and  and  differences  result i s consistent with  f i n d i n g s w h i c h have i n d i c a t e d t h e  the  difference  b e t w e e n f e e t , a d d e d f a c t o r s s u c h as w e i g h t b e a r i n g , and  angles  non-weight  bearing  p r o c e s s showed no  the  tibial  r e s u l t s are  shown i n F i g u r e  d i f f e r e n c e was  7.  A  statistically  found between the p o s i t i o n s  t u b e r o s i t y when c o m p a r i n g t h e 36  two  the  types  of  of  B vs F sig., p • 0.000; R vs L sig., p • 0.037  cm  0.0  RIGHT H  LEFT BOOT  E D FOOTBED  Figure 7. Tibial tubercle horizontal distance from midline.  RB - R i g h t B o o t LB - L e f t B o o t  RF - R i g h t F o o t b e d LF - L e f t F o o t b e d  37  insoles. midline  The t u b e r o s i t y when t h e s u b j e c t s  footbeds.  was s i g n i f i c a n t l y  closer to the  were u s i n g t h e custom molded  T h i s f i n d i n g was t r u e  f o r b o t h t h e r i g h t and l e f t  f e e t . T h i s r e s u l t was a t t r i b u t e d t o t h e c u s t o m m o l d e d footbed a l t e r i n g the p o s i t i o n of the foot which i n turn changed t h e alignment o f t h e lower limb. statistically the  significant difference  tuberosity  T h e r e was a  between t h e l o c a t i o n o f  f o r t h e r i g h t and l e f t  feet.  Separate  statistical  a n a l y s e s p e r f o r m e d on e a c h t y p e o f i n s o l e  showed t h a t  t h i s s i g n i f i c a n c e o c c u r r e d when u s i n g t h e n o n -  custom i n s o l e s .  The c u s t o m m o l d e d f o o t b e d s showed no  significant difference tuberosity indicated  between t h e p o s i t i o n  o f t h e r i g h t and l e f t that  alone  feet.  This  of the t i b i a l result  t h e custom molded footbeds b o t h d e c r e a s e d t h e  amount o f t i b i a l  r o t a t i o n and m i n i m i z e d t h e between l e g  differences. Summary. The c u s t o m m o l d e d f o o t b e d s m a i n t a i n e d t h e navicular  tubercle  i n a position  i n s i d e o f the s k i boot  w h i c h was b o t h h i g h e r a n d f a r t h e r b a c k a s c o m p a r e d t o t h e non-custom i n s o l e s  a t b o t h t h e s t a r t and end p o s i t i o n s .  T h i s was due t o t h e t h i c k n e s s the  change i n f o o t  Further,  o f t h e f o o t b e d as w e l l  as t o  p o s i t i o n b r o u g h t about by t h e f o o t b e d .  t h e custom footbeds a l l o w e d l e s s f o r w a r d and  downward m o t i o n o f t h e n a v i c u l a r  than d i d the i n s o l e s  when  moving from t h e s t a r t t o t h e end p o s i t i o n . The end  rearfoot  a n g l e was s m a l l e r  a t b o t h t h e s t a r t and  p o s i t i o n when u s i n g t h e c u s t o m f o o t b e d a s c o m p a r e d t o 38  the non-custom i n s o l e . footbed.  due  T h e r e was  to the  f o o t by  the  amount o f m o t i o n t h a t e i t h e r o f t h e t y p e s when m o v i n g f r o m t h e  The  d i f f e r e n c e between  maintained  of the  f o o t by  Skiing  Section  the  Again,  the  this  i s due  c o n t r o l , p a i n , and  a n a l o g u e s c a l e s w e r e u t i l i z e d by  fatigue while  Edge C o n t r o l . The  s u b j e c t s gave t h e  category  o f edge c o n t r o l .  s h o r t r a d i u s and  p a i n w i t h t h e use non  significant. an  The  the  the  long radius  The  slight  group  data  non-custom  T h i s was  true  slightly  f i g u r e s were  i n c r e a s e i n p a i n was  than  A d j u s t m e n t s s u c h as b u c k l e  t h i c k n e s s w i t h t h e use more t i m e t h a n was  o f any  new  available during t h i s  n o t e d t h a t most s u b j e c t s e x p e r i e n c e d  with  attributed to  t i g h t n e s s and  footbed  more  not  i n s u f f i c i e n t b r e a k - i n p e r i o d when u s i n g t h e new  footbeds.  for  turns.  custom molded footbeds  custom i n s o l e s , the  edge  custom molded  subjects experienced  of the  the  8-10.  s i g n i f i c a n t l y h i g h e r marks t h a n t h e  Pain. Although  t h e i r own  skiing.  with  s c a l e s are d i s p l a y e d i n F i g u r e s  i n s o l e s i n the  the  to the r e p o s i t i o n i n g  subjects i n order to rate t h e i r experiences  both the  tibial  footbed.  Horizontal visual  footbeds  position.  i n a p o s i t i o n c l o s e r to the m i d - l i n e than d i d  non-custom i n s o l e s .  from these  of i n s o l e s  s t a r t t o t h e end  custom molded footbeds  tuberosity  no  r e p o s i t i o n i n g of  the  allowed  the  T h i s was  custom sock  or s k i boot study.  It  take was  l e s s p a i n as t h e y  spent  more t i m e i n t h e c u s t o m f o o t b e d s  b u t were i n s t r u c t e d t o  c o m p l e t e t h e r a t i n g s s c a l e b a s e d on t h e i r o v e r a l l during the entire test Fatigue. significantly footbeds  period.  The s u b j e c t s  t h a n w i t h t h e non-custom  through a race  it  f e e t a n d l e g s t o be  insoles.  were t i m e d  course.  group were s i g n i f i c a n t l y footbeds  found t h e i r  l e s s f a t i g u e d a f t e r s k i i n g w i t h t h e custom  Timed Runs. S u b j e c t s trials  fora total  The a v e r a g e t i m e s  a s c o m p a r e d t o t h e non c u s t o m i n s o l e s .  when u s i n g t h e c u s t o m f o o t b e d s  custom i n s o l e s . Although course  a l l four times,  of four f o r the  f a s t e r when u s i n g t h e c u s t o m m o l d e d  was n o t e d t h a t a l l s u b j e c t s h a d e q u i v a l e n t  times  impression  In addition  or faster  a s c o m p a r e d t o t h e non  each s u b j e c t  s k i e d t h e same  race  t h e e f f e c t s o f l e a r n i n g were  c o n t r o l l e d by t h e d i v i s i o n  o f t h e group i n t o two s u b g r o u p s .  W h i l e h a l f o f t h e s u b j e c t s s k i e d t h e i r t h i r d and f o u r t h runs u s i n g t h e custom footbeds, their  first  Summary.  t h e other h a l f o f t h e group s k i e d  and second runs u s i n g t h e custom  footbeds.  The s u b j e c t g r o u p r a t e d t h e c u s t o m f o o t b e d s  as  s i g n i f i c a n t l y b e t t e r than t h e custom i n s o l e s i n p r o v i d i n g edge c o n t r o l f o r b o t h s h o r t a n d l o n g r a d i u s t u r n s . footbeds  were a l s o r a t e d as c a u s i n g  f a t i g u e t h a n non-custom i n s o l e s . f i n d any s t a t i s t i c a l l y of pain experienced  significant  significantly  less  The s u b j e c t g r o u p d i d n o t differences i n the level  while using e i t h e r type  40  The  of insoles.  B vs F sig., p • 0.000 100  i  100  B vs F sig.. p • 0.001  i  BOOT  ,  FOOTBED  Figure 8b. Edge control ratings for long radius turns.  B - Boot  F- F o o t b e d  41  B vs F not sig.  100  75  S C  o  R E  50  S.O. 17.886 S.D. 17.91  1 0 0  25  BOOT  FOOTBED  Figure 9a. Pain ratings.  B vs F sig., p - 0.005  100  75 S C O R E / 1 0 0  50  S.D. 18.27 S.D. 20.149  25  BOOT  FOOTBED  Figure 9b. Fatigue ratings.  B - Boot  F - Footbed  42  19.00  TIME (SEC)  B vs F sig., p • 0.000  18.50  18.00 17.76 • / - 1.15  17.50  17.00  BOOT  FOOTBED  Figure 10. Race results.  B - Boot  F - Footbed  43  Chapter 5 CONCLUSIONS AND RECOMMENDATIONS T h i s i n v e s t i g a t i o n was d e s i g n e d t o t e s t t h e h y p o t h e s i s t h a t custom molded s k i boot  footbeds could c o n t r o l t h e  e v e n t s a s s o c i a t e d w i t h p r o n a t i o n more e f f e c t i v e l y t h a n n o n custom i n s o l e s .  The c o n t r o l o f p r o n a t i o n was t e s t e d b y  a n a l y z i n g t h e r e l a t e d motions landmarks.  o f v a r i o u s f o o t and lower l e g  N a v i c u l a r d r o p was m o n i t o r e d a s i t r e f l e c t s t h e  c o l l a p s i n g o f t h e medial arch which  accompanies t h e  a b d u c t i o n and a n k l e e v e r s i o n a s s o c i a t e d w i t h p r o n a t i o n . R e a r f o o t a n g l e was c h o s e n and a n k l e e v e r s i o n .  as a n o t h e r i n d i c a t o r o f a b d u c t i o n  The l o c a t i o n o f t h e t i b i a l  monitored because t i b i a l accompany p r o n a t i o n .  t u b e r c l e was  r o t a t i o n h a s b e e n shown t o  The r e s u l t s o f t h e i n v e s t i g a t i o n  showed t h e c u s t o m f o o t b e d s t o c o n t r o l n a v i c u l a r d r o p a n d tibial  r o t a t i o n more e f f e c t i v e l y t h a n t h e n o n - c u s t o m  insoles.  The amount o f r e a r f o o t a n g l e a t b o t h t h e s t a r t a n d  e n d p o s i t i o n s was s i g n i f i c a n t l y custom f o o t b e d s even though It  o v e r a l l m o t i o n was n o t a f f e c t e d .  was h y p o t h e s i z e d t h a t c u s t o m f o o t b e d s c o u l d  edge c o n t r o l , to  changed w i t h t h e use o f  decrease p a i n and decrease  non-custom i n s o l e s .  f a t i g u e as compared  The r e s u l t s o f t h e i n v e s t i g a t i o n  i n d i c a t e d t h a t t h e t e s t group i n c r e a s e edge c o n t r o l  f e l t t h a t custom footbeds d i d  i n b o t h s h o r t and l o n g r a d i u s t u r n s ,  a n d d e c r e a s e d t h e amount o f f a t i g u e e x p e r i e n c e d . did  n o t r e p o r t any s i g n i f i c a n t  pain experienced.  improve  The g r o u p  differences i n the level of  These r e s u l t s were b a s e d  on p u r e l y  subjective analyses.  Timed r u n s t h r o u g h a r a c e  course  r e s u l t e d i n f a s t e r t i m e s f o r s k i e r s when u s i n g t h e c u s t o m f o o t b e d s as compared t o t h e non-custom i n s o l e s . I t was b e l i e v e d t h a t m a i n t a i n i n g  the subtalar  joint i n  a more n e u t r a l p o s i t i o n w o u l d r e s u l t i n a l l t h e s k i i n g improvements p r e v i o u s l y d i s c u s s e d .  From t h e d i f f e r e n c e s i n  l a n d m a r k p o s i t i o n s i n b o t h s t a r t a n d e n d p o s i t i o n s when c o m p a r i n g t h e two t y p e s o f i n s o l e s , i t a p p e a r s t h a t t h e custom f o o t b e d s e f f e c t i v e l y s k i boot. study,  realigned the foot within the  Because o f t h e molding t e c h n i q u e u t i l i z e d  i t i s assumed t h a t t h e f o o t b e d  does m a i n t a i n  i n a n e u t r a l p o s i t i o n during weight bearing. the  realignment o f the foot, the footbed  any  gaps under t h e f o o t and p r o v i d e  c o m p r e s s i b l e base o f support. factors likely during  this  responsible the  allows  to f i l l i n  minimally  The c o m b i n a t i o n o f t h e s e t w o  f o r the c o n t r o l of motion  investigation.  the foot  In addition t o  served  a solid,  i n this  witnessed  I t i s a l s o b e l i e v e d t o be  f o r an i m p r o v e d t r a n s m i s s i o n  of forces  between  s k i e r a n d t h e b o o t , r e s u l t i n g i n b e t t e r edge c o n t r o l a n d  decreased e f f o r t t o carve a turn. The three  subjects  i n this  s t u d y e x h i b i t e d more t h a n  d e g r e e s o f s u b t a l a r v a r u s when m e a s u r e d i n a n o n -  weight bearing in  utilized  position.  The e f f e c t i v e n e s s o f t h e f o o t b e d s  c o n t r o l l i n g t h e motion e x p e r i e n c e d by t h e s e  subjects  c o u l d be t h o u g h t t o i n d i c a t e a s i m i l a r e f f e c t i v e n e s s when f o o t b e d s a r e u s e d by s k i e r s w i t h  45  l e s s e r degrees o f  malalignment.  However, t h e  s k i e r s would not  use  o f t h i s p r o d u c t by  n e c e s s a r i l y be  such  indicated.  Conclusions B a s e d upon t h e conclusions 1. a)  r e s u l t s of t h i s  w e r e made w i t h  study, the  regards t o the  following  hypotheses:  Custom molded f o o t b e d s c o n t r o l l e d t h e  drop a s s o c i a t e d w i t h pronation  navicular  more e f f e c t i v e l y t h a n n o n -  custom i n s o l e s . b)  Custom f o o t b e d s r e a l i g n e d t h e  as t o d e c r e a s e t h e  r e a r f o o t a n g l e as c o m p a r e d t o  experienced w i t h the footbeds d i d not  subtalar  use  Custom  amount o f r e a r f o o t m o t i o n  compared t o t h a t e x p e r i e n c e d w i t h the  use  of  so  that  of non-custom i n s o l e s .  reduce the  joint  as  non-custom  insoles. c)  Custom molded f o o t b e d s r e a l i g n e d t h e  l o w e r l e g so as t o m a i n t a i n p o s i t i o n c l o s e r to center of the  tibial  and  tubercle in a  than that experienced w i t h the  use  non-custom i n s o l e .  2.  The  hypothesis  amount o f p a i n the  the  foot  experienced while  f i n d i n g s of t h i s 3.  The  use  decrease i n the g r o u p as  t h a t custom footbeds d e c r e a s e s k i i n g was  not  the  supported  by  study.  of custom footbeds r e s u l t e d i n a amount o f f a t i g u e r e p o r t e d  compared t o t h a t r e p o r t e d  custom i n s o l e s .  46  w i t h the  by  the  use  subjective subject  of the  non-  4.  The  use  of custom footbeds  r e s u l t e d i n an  i m p r o v e m e n t i n t h e amount o f edge c o n t r o l r e p o r t e d by test  the  group. 5.  The  race times  use  of custom footbeds  r e s u l t e d i n improved  f o r the s u b j e c t group.  Recommendations The  ability  o f custom molded s k i boot footbeds  c o n t r o l s u b t a l a r m o t i o n and supported use  by t h i s  o f one  study.  to  enhance t h e s k i i n g e x p e r i e n c e  T h e s e f i n d i n g s w e r e b a s e d on  s t y l e of footbed.  At the p r e s e n t  the  time there  are  o t h e r s t y l e s o f custom f o o t b e d b e i n g marketed t o  skiers.  S k i e r s s h o u l d be  available  aware t h a t some o f t h e  do n o t p r o v i d e a s o l i d b o t t o m and may compressible, forward weight  transfer.  t h e method o f m o l d i n g  the  c o n t r o l they provide.  In a d d i t i o n ,  The  footbeds  from t h e use  t h e use  different  as w e l l  as  a l t e r t h e amount o f  c o n s u m e r s h o u l d be  aware o f  i n order to  of a custom molded  directions  of  footbeds,  can  d i f f e r e n c e s i n the a v a i l a b l e products  Future  t h e r e f o r e be h i g h l y  a l l o w i n g more m o t i o n a t t h e n a v i c u l a r w i t h  m a t e r i a l s i n the c o n s t r u c t i o n of the  benefit  footbeds  is  the  fully  footbed.  f o r research i n t h i s area  should  i n c l u d e l a b o r a t o r y t e s t i n g i n c o r p o r a t i n g the p r o t o c o l utilized  in this  study  of s k i boot footbeds.  f o r the analyses  of d i f f e r e n t  F i e l d r e s e a r c h s h o u l d be  types  performed  d o c u m e n t i n g i n j u r y r a t e s among s k i e r s u s i n g c u s t o m m o l d e d footbeds.  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(Ed.), B i o m e c h a n i c s o f R u n n i n g Shoes, 117-137. Human K i n e t i c s , Champaign, I l l i n o i s . S u b o t n i c k , S . I . (1982). Foot orthoses i n s k i boots. The P h y s i c i a n a n d S p o r t s M e d i c i n e , 10, 61-68. S u p e r f e e t Inshoe  System.  T e c h n i c a l Manual.  (1983).  W a l k h o f f , K., a n d Baumann, C.W. ( 1 9 8 7 ) . A l p i n e s k i b o o t hysteresis characteristics interpreted f o rskier target groups w i t h i n t h e c u r r e n t standards. I n Mote J r . , C D . and J o h n s o n , R . J . ( E d s . ) , S k i i n g Trauma a n d S a f e t y 6 t h I n t e r n a t i o n a l Symposium, 127-144. ASTM, P h i l a d e l p h i a , Pennsylvania.  49  APPENDIX A DETERMINATION OF  LOWER LIMB ALIGNMENT.  Leg - h e e l a l i g n m e n t ( s u b t a l a r v a r u s ) - s u b j e c t i n prone p o s i t i o n w i t h f e e t extended c l e a r of the examining t a b l e - mark m i d l i n e o f t h e c a l c a n e u s a t i n t e r s e c t i o n o f A c h i l l e s t e n d o n and a t a p o i n t 1.5cm distal - p l a c e two a d d i t i o n a l m a r k s on t h e m i d l i n e o f t h e d i s t a l 1/3 o f t h e l e g t o r e p r e s e n t t h e l o n g i t u d i n a l a x i s of the t i b i a - place the s u b t a l a r j o i n t i n n e u t r a l p o s i t i o n : s t a b i l i z e t h e f o r e f o o t by a p p l y i n g p r e s s u r e u n d e r t h e f o u r t h and f i f t h m e t a t a r s a l h e a d s and d o r s i f l e x u n t i l the point of r e s i s t a n c e , then i n v e r t / e v e r t the foot through the arc of motion u n t i l the balance point i s i d e n t i f i e d - measure t h e angle between the l o n g i t u d i n a l a x i s of t h e l e g and h e e l u s i n g a g o n i o m e t e r James(1979) Forefoot - heel alignment (forefoot varus) - p l a c e s u b j e c t i n prone p o s i t i o n w i t h f e e t extended c l e a r of the examining t a b l e - m a r k s on c a l c a n e u s f r o m t h e p r e v i o u s m e a s u r e m e n t a r e u s e d as r e f e r e n c e s f o r t h e h e e l , t h e p l a n e o f t h e m e t a t a r s a l heads i s u s e d i n r e f e r e n c e t o t h e s e marks - v a r u s a l i g n m e n t i s s a i d t o be p r e s e n t i f t h e p l a n e of the f o r e f o o t at the m e t a t a r s a l head l e v e l i s such t h a t t h e m e d i a l s i d e o f t h e f o o t r i s e s above a perpendicular plane James(1979) Functional Hypermobility - s u b j e c t i s w e i g h t b e a r i n g , s t a n d i n g on t h e f l o o r - o b s e r v e t h e movement o f t h e g r e a t t o e , t h e f l a t t e n i n g o f t h e a r c h / n a v i c u l a r d r o p , and t i b i a l r o t a t i o n / k n e e valgus w i t h weight bearing  50  APPENDIX B FOOTBED MOLDING PROCEDURE. 1. R e a r / M i d f o o t M o l d i n g - s u b j e c t i s s e a t e d c o m f o r t a b l y , shoes and socks o f f - p o s i t i o n t h e " 3 / 4 t h o t i c s " on t h e h e a t i n g p a d d l e s , a n d i n s i d e t h e o v e n (160 ^C) f o r a p p r o x . l O m i n . ; p o s i t i o n t h e b l a n k s a b o v e t h e o v e n t o p i c k up a m b i e n t h e a t - w h i l e p o s i t i o n i n g t h e 3 / 4 t h o t i c on t h e m o l d i n g c a p , i n s e r t t h e r e a r p a r t o f t h e b l a n k i n t o t h e o v e n t o warm s l i g h t l y b e f o r e p o s i t i o n i n g t h e b l a n k on t h e 3 / 4 t h o t i c (max. t i m e i n o v e n i s 20 s e c , t h i s e n s u r e s p r o p e r b o n d i n g o f t h e b l a n k a n d the 3/4thotic) - remove 3 / 4 t h o t i c f r o m s p a t u l a b y t a p p i n g a g a i n s t t h e b e n c h - c e n t e r t h e 3 / 4 t h o t i c and blank f l a n g e s f l u s h w i t h t h e f l a n g e s o f t h e molding cap - t a c k a l l edges t o g e t h e r - c e n t e r t h e p a r t s a g a i n s t t h e bottom o f t h e f o o t and g e n t l y s l i d e t h e h e e l o f t h e f o o t i n t o t h e h e e l cup - fasten the retaining strap - check t h a t t h e h e e l i s i n t h e back o f t h e s k i t h o t i c , t h e l o n g a x i s o f t h e f o o t and t h e s k i t h o t i c a r e i n a l i g n m e n t w i t h t h e c a p , and t h e s k i t h o t i c and t h e cap a r e perpendicular t o the long axis of the l e g - s l i p on t h e p l a s t i c s o c k , p u l l up f r o m h e e l , a n d s e c u r e w i t h a n k l e c i n c h band - t u r n on vacuum pump. - a s a i r e v a c u a t e s , g e n t l y h o l d down t h e f i r s t m e t a t a r s a l head - p o s i t i o n t h e f o o t i n a l o c k e d , n e u t r a l p o s i t i o n (as d e s c r i b e d i n James 197 9 - s e e A p p e n d i x A) - h a v e s u b j e c t s t e p down on t h e o t h e r f o o t a n d s l o w l y p u t t h e down t h e ' o r t h o t i c ' f o o t j u s t t o t h e p o i n t o f c o n t a c t w i t h t h e g r o u n d - no w e i g h t - t u r n o f f t h e vacuum - s u b j e c t f l e x e s b o t h knees forward s l i g h t l y , g e n t l y t r a n s f e r s weight t o both feet e q u a l l y - maintain n e u t r a l , locked p o s i t i o n - t u r n vacuum b a c k o n , h a v e t h e s u b j e c t l i f t t h e f o o t a g a i n and s i t down f o r 30 s e c o n d s - a l l o w p a r t s t o c o o l f o r 2 min b e f o r e s e p a r a t i n g t h e f o o t b e d from t h e molding cap 2. F o r e f o o t M o l d i n g - p o s i t i o n f o o t b e d s a b o u t h a l f way i n t o t h e o v e n f o r 3 m i n - do n o t h e a t more t h a n 3-4cm b e y o n d t h e l e a d i n g edge o f t h e 3 / 4 t h o t i c so as n o t t o s o f t e n t h e m e d i a l a r c h o r c u b o i d areas - p o s i t i o n t h e s k i t h o t i c a n d m o l d i n g c a p s q u a r e l y on t h e f o o t w i t h an i n s u l a t i o n p a d p l a c e d between t h e f o o t and footbed - h a v e s u b j e c t s t e p down on t h e o t h e r f o o t a n d b r i n g f o o t b e d f o o t down t o t h e p o i n t o f c o n t a c t i n g t h e g r o u n d - no w e i g h t 51  - check t h a t h e e l i s i n p o s i t i o n , b a l l o f f o o t and m e d i a l edges o f f o o t b e d and molding cap a r e a l l f l u s h - g a t h e r t o e s t o g e t h e r as t h e y w o u l d be i n a s k i b o o t - h o l d t o e s a n d f o r e f o o t down, g e n t l y l i f t t h e h e e l w i t h t h e o t h e r hand - have s u b j e c t t r a n s f e r a l l t h e weight t o t h e f o o t b e d and h o l d f o r 5 seconds - t r a n s f e r weight back t o t h e o t h e r f o o t and lower t h e h e e l s l o w l y w i t h o u t w e i g h t - g u i d e t h e h e e l u n t i l c o n t a c t i s made - g e n t l y p u s h t o e s down w i t h t h e p a l m o f y o u r h a n d t o p h e l p increase d e f i n i t i o n - p u s h down on t h e f i r s t m e t a t a r s a l h e a d w h i l e t h e r e a r f o o t remains n e u t r a l - without weight 3. F i n i s h i n g t h e F o o t b e d s - use s k i b o o t ' s s t a n d a r d i n s o l e t o t r a c e l e n g t h and shape onto f o o t b e d - t r i m back, l e a v i n g f o o t b e d s l i g h t l y l o n g e r t h a n t h e i n s o l e ( l e a v e even l o n g e r f o r r e a r e n t r y boots) - use a w i r e - b r u s h wheel t o g r i n d o f f excess cork i n t h e arch area - u s e t h e edge o f a s t o n e w h e e l t o c u t b a c k a n y o t h e r e x c e s s and t o l e a v e a s m o o t h f i n i s h - k e e p t h e f l a n g e edge t h i n , b u t no l e s s t h a n 1mm - keep t h e h e e l cup as v e r t i c a l as p o s s i b l e - f i t t h e footbed i n t o t h e boot, t r i m i f necessary Superfeet  T e c h n i c a l Manual(1983)  52  APPENDIX C GENERAL D E S C R I P T I V E DATA FOR A L L SUBJECTS Table C - l General D e s c r i p t i v e Data f o r a l l Subjects Age(yrs) 28 24 21 23 27 24 18 23 36 23 23 25 28 28 26 25.13 3.96  Height(cm) 170 170 177.5 162.5 175 177.5 180 175 177.5 167.5 172.5 162.5 167 .5 170 162.5  Weight(kg) 70.4 76.4 81.8 61.4 77.3 65.9 70.4 80.4 79.5 61.4 68.2 56.8 65. 9 70 . 45 70. 9  171.17 5.69  70.48 7.25  SV - S u b t a l a r V a r u s  (Right/Left)  53  Skiing(yrs) 20 16 12 13 15 18 12 10 21 14 17 16 15 20 13 15.47 3.16  SV R L 6 5 7 8 4 4 5 4 5 6 9 4 6 4 5 4 8 6 4 6 7 5 4 3 5 4 5 6 4 5 5.6/4 .9 1.5/1 .2  APPENDIX D COMPLETE NAVICULAR DATA. Table D - l Right Foot  SBX EBX SBY EBY  - L o c a t i o n o f N a v i c u l a r ( c m ) , Average o f 2 T r i a l s  SBX 9 .595 9 .225 7 .335 8 .4 65 8 .225 8 .81 7 . 695 8 .03 8 .565 7 .8 8 .46 8 .01 8 .36  SFX 9. 6 9. 29 8. 125 8. 575 10 .71 9. 635 7. 855 8. 1 8. 595 7. 84 9. 52 8. 06 8. 74  EBX 9 .035 8 .0 6 .56 7 .855 7 .275 8 .165 7 .405 7 .08 7 . 66 6 .84 7 .675 7 .07 7 .575  8 .352 0 .619  8. 819 0. 837  7 .553 8. 622 0 . 642 0. 801  -  S t a r t , boot, End, boot, x S t a r t , boot, End, boot, y  x axis axis y axis axis  EFX 9. 28 9. 135 7 .975 8 .42 10 .39 9. 26 7 .83 7 .965 8. 42 7. 715 9. 33 7. 865 8. 495  SBY 7. 38 6. 39 6. 385 6. 21 6. 455 6. 325 7. 51 6. 89 6. 625 5. 62 5. 515 6. 36 6. 51  SFY 7 .79 7 .125 7 .79 6 .70 7 .16 6 .84 7 . 935 7 .48 7 .385 6 .765 7 .75 7 .325 7 .03  EBY 6. 825 5. 715 5. 91 5. 485 6. 075 6. 16 7. 06 6. 415 6. 105 5. 21 5. 09 5. 825 6. 17  EFY 6. 825 7 .11 7. 73 6. 595 7. 045 6. 83 7 .64 7. 45 7. 34 6. 745 7 .545 7 .26 6. 925  6. 475 0. 567  7 .313 0 .419  6. 003 0. 569  7. 157 0. 367  SFX EFX SFY EFY  54  -  Start, footbed, End, f o o t b e d , x S t a r t , footbed, End, f o o t b e d , y  x axis axis y axis axis  T a b l e D-2 L e f t F o o t - L o c a t i o n o f N a v i c u l a r ( c m ) , A v e r a g e o f Two  SBX EBX SBY EBY  -  Trials  SBX SFX 8 .385 8 .78 8 .43 8 . 61 8 .35 8 .11 8 .765 9 .22 9 .075 9 .57 9 .535 10 .435 8 .895 8 .96 7 .23 7 .51 8 .26 8 .41 7 .59 6 .665 7 .55 7. 6 7 .28 7 . 625 7 . 675 8 .03  EBX EFX 7.475 8.51 7.91 8.37 7.50 8.04 8.24 9.06 8.475 9.495 8.64 10.245 8.06 8.865 6.41 7.38 7.415 8.245 7.205 7.475 6.695 7.36 6.485 7.565 7.515 7.68  SBY 6. 89 5. 93 6. 255 6. 105 7. 145 7 .085 7. 225 7. 125 6. 735 5. 79 6. 695 6. 845 5. 615  SFY 7. 535 6. 83 6. 995 6. 62 7. 67 7. 77 7. 86 7. 79 7. 665 6. 845 6. 69 7. 56 6. 54  EBY 6.59 5.295 5.54 5.68 6.77 6.915 7.005 6.56 6.235 5.45 5.99 6.3 5.345  EFY 7.51 6.77 6.935 6.425 7.56 7.74 7.75 7.62 7.56 6.80 6.62 7.41 6.495  8 .143 0 .829  7.540 0.720  6. 572 0. 563  7. 259 0. 507  6.129 0.617  7.169 0.501  8 .515 0 .882  S t a r t , boot, End, boot, x S t a r t , boot, End, boot, y  x axis axis y axis axis  8.253 1.000  SFX EFX SFY EFY  55  -  Start, footbed, x axis End, f o o t b e d , x a x i s Start, footbed, y axis End, f o o t b e d , y a x i s  T a b l e D-3 N a v i c u l a r Range o f M o t i o n , A v e r a g e  Mean SD  RIGHT Boot (x .56 1.225 .77 .71 .95 .645 .29 .95 .905 .91 .785 .94 .785 .802 .227  y) .55 .675 .475 .725 .38 .165 .45 .475 .52 .41 .425 .535 .34  Footbed (x .32 .155 .15 .155 .32 .375 .025 .135 .175 .125 .19 .15 .245  .472 .143  .194 .096  o f Two  Trials  y) .085 .015 .06 .105 .115 .01 .295 .03 .045 .02 .205 .065 .105  LEFT Boot (x .91 .52 .61 .525 .6 .895 .835 .82 .845 .54 .855 .795 .655  y) .3 .635 .715 .425 .375 .17 .22 .565 .5 .34 .705 .545 .27  Footbed (x y) .27 .025 .24 .12 .31 .06 .16 .195 .075 .11 .19 .03 .095 .11 .13 .17 .165 .105 .115 .045 .24 .07 .06 .15 .35 .045  .089 .082  .723 .150  .443 .182  .185 .092  56  .095 .055  T a b l e D-4 A n a l y s i s o f Variance - Right Foot, L o c a t i o n o f N a v i c u l a r Source  Sums o f Squares  Mean Squares  DF  F Ratio  SBX v s SFX Error  1.417 2.983  1.417 0.249  1 12  5.701  0.034  EBX v s EFX Error  7.415 3.133  7.415 0.261  1 12  28.400  0.000  SBY v s SFY Error  4.570 3.133  4.570 0.261  1 12  34.710  0.000  EBY v s EFY Error  8.648 2.265  8.648 0.189  1 12  45.822  0.000  SBX EBX SBY EBY  -  S t a r t , boot, End, boot, x S t a r t , boot, End, b o o t , y  x axis axis y axis axis  SFX EFX SFY EFY  57  -  Start, footbed, End, f o o t b e d , x Start, footbed, End, f o o t b e d , y  P  x axis axis' y axis axis  T a b l e D-5 A n a l y s i s of Variance - L e f t Foot, L o c a t i o n o f N a v i c u l a r Source  Sums o f Squares  Mean Squares  DF  F Ratio  SBX v s SFX Error  0.899 0.459  0 .899 0.038 .  1 12  23.503  0.000  EBX v s EFX Error  3.302 1.043  3.302 0.087  1 12  37.972  0.000  SBY v s SFY Error  3.067 0.420  3.067 0.035  1 12  87.660  0.000  EBY v s EFY Error  7.030 0.488  7.030 0.041  1 12  173.012  0.000  SBX EBX SBY EBY  -  S t a r t , boot, End, boot, x S t a r t , boot, End, b o o t , y  SFX EFX SFY EFY  x axis axis y axis axis  58  -  Start, footbed, End, f o o t b e d , x Start, footbed, End, f o o t b e d , y  x axis axis y axis axis  T a b l e D-6 A n a l y s i s o f V a r i a n c e - Range o f M o t i o n , X D i r e c t i o n , B o o t v s Footbed Source  Sums o f Squares  Mean Squares  DF  F Ratio  Within Subjects R vs L 0.025 Error 0.345  0.025 0.029  1 12  0.877  0.368  B vs F Error  4.278 0.176  4.278 0.015  1 12  292.314  0.000  Interaction Error  0.016 0.374  0.016 0.031  1 12  0.506  0.491  59  P  T a b l e D-7 A n a l y s i s o f V a r i a n c e - Range o f M o t i o n , Y D i r e c t i o n , B o o t v s Footbed " ' " Source  Sums o f Squares  Mean Squares  DF  F Ratio  Within Subjects R vs L 0.002 Error 0.119  0.002 0.010  1 12  0.158  0.698  B vs F Error  1.737 0.229  1.737 0. 019  1 12  91.227  0.000  Interaction Error  0.004 0.113  0.004 0.009  1 12  0.405  0.537  60  APPENDIX E COMPLETE REARFOOT DATA. Table E - l Rearfoot Angle, RBS 6.75 5.5 5.75 4.25 8.5 7.5 6.5 3.0 6.25 7.0 5.0 5.75 4.25 Mean 5.846 SD 1.488  RBS RBE LBS LBE  -  A v e r a g e o f Two T r i a l s  RBE 6.0 5.25 5.5 3.5 8.75 7.5 5.75 4.5 4.5 5.5 4.25 6.0 3.5  RFS 3.5 4.25 3.0 3.5 4.5 3.5 3.0 2.75 3.5 4.25 3.25 3.25 2.0  RFE 3.0 4.25 2.75 2.25 4 .75 3.0 2.25 4.0 3.75 3.5 3.0 2.75 1.25  LBS 4.0 2.5 3.75 5.75 4.25 3.0 5.5 5.75 4.0 4.0 3.75 5.25 4.25  LBE 3.5 2.0 3.5 5.5 4.0 2.75 5.25 4 .25 3.25 2.75 3.25 5.0 4.0  LFS 1.25 1.5 2.0 3.0 1.5 1.75 2.0 1.0 1.625 1.5 1.5 1.5 1.0  LFE 1.0 1.25 2.0 3.5 1.75 2.0 1.5 0.5 1.25 1.5 1.25 1.0 1.0  5.423 1.491  3.404 0.673  3.115 0.939  4.288 1.015  3.769 1.038  1.625 0.515  1.500 0.736  R i g h t , boot, s t a r t R i g h t , boot, end L e f t , boot, s t a r t L e f t , boot, end  RFS RFE LFS LFE  61  -  Right, Right, Left, Left,  footbed, s t a r t footbed, end footbed, s t a r t footbed, end  T a b l e E-2 A n a l y s i s of Variance - Rearfoot Angle, vs Footbed Source  Mean Squares  DF  F Ratio  Within Subjects R vs L 36.181 Error 20.089  36.181 1.674  1 12  21.612  0.001  B vs F Error  84.724 5.421  84.724 0.452  1 12  187.557  0.000  0.159 9.704  0.159 0.809  1 12  0.197  0.665  Interaction Error  Sums o f Squares  S t a r t P o s i t i o n , Boot  62  P  T a b l e E-3 A n a l y s i s of Variance - Rearfoot Angle, Footbed " ~ Source  Sum o f Squares  End P o s i t i o n , Boot v s ' "  Mean Squares  DF  F Ratio  Within Subjects R vs L 34.736 Error 24.764  34.736 2.064  1 12  16.832  0.001  B vs F Error  68.082 8.918  68.082 0.743  1 12  91.608  0.000  0.005 8.495  0.005 0.708  1 12  0.007  0.936  Interaction Error  63  P  APPENDIX F COMPLETE T I B I A L  TUBEROSITY DATA.  Table F - l D i s p l a c e m e n t o f t h e T i b i a l T u b e r o s i t y From C e n t e r , o f Two T r i a l s  Mean SD  RBX 2.33 1.405 1.53 2.46 2.235 2.305 2.67 1.835 2.97 2.625 2.06 1.38 3.13  RFX 1.315 0.98 1.285 1.185 1.345 2.025 1.72 1.355 1.215 1.545 2.355 0.815 1.035  LBX 1 .85 0 . 95 1 .22 2 .065 1 .205 1 .25 2 . 605 2 . 185 2 .29 1 .74 1 . 97 1 .8 3 .05  LFX 0 .38 0 . 645 0 .88 2 .39 0 .8 0 .3 1 .72 1 . 61 0 .78 0 . 935 1 . 69 0 .95 1 .095  2.226 0.567  1.398 0.427  1 .860 0 . 604  1 .090 0 .599  RBX - R i g h t , b o o t , x d i r . LBX - L e f t , b o o t , x d i r .  Average  RFX - R i g h t , f o o t b e d , x d i r . LFX - L e f t , f o o t b e d , x d i r .  64  T a b l e F-2 A n a l y s i s o f Variance - T i b i a l Rotation, Displacement i n the X D i r e c t i o n , Boot vs Footbed Source  Sum o f Squares  Mean Squares  DF  F Ratio  P  Within R vs L Error  Subjects 1.474 3.208  1.474 0.267  1 12  5.513  0.037  B vs F Error  8.292 3.768  8.292 0.314  1 12  26.405  0.000  Interaction Error  0.011 1.003  0.011 0.084  1 12  0.131  0.724  RBX - R i g h t , b o o t , x d i r . LBX - L e f t , b o o t , x d i r .  RFX - R i g h t , f o o t b e d , x d i r . LFX - L e f t , f o o t b e d , x d i r .  65  APPENDIX G COMPLETE RATINGS DATA. Table G - l S u b j e c t i v e R a t i n g s Out o f 100 f o r Edge C o n t r o l , P a i n , a n d Fatigue LRF 76 66 53 72 72 83 58 73 62 83 73 48 90 85 85 71.9 12.5  LRF SRF PF FF  -  LRB 40 32 21 39 42 27 84 44 41 68 46 65 59 56 65  SRF 81 70 53 66 81 98 79 79 62 89 69 66 74 78 74  SRB 31 39 23 31 44 30 77 41 35 62 57 65 64 46 61  PF 11 59 62 58 40 75 46 53 18 33 33 41 43 24 60  PB 31 44 43 50 30 75 3 37 40 27 42 59 66 22 33  FF 10 31 25 55 28 63 2 24 24 61 34 70 24 29 53  48.6 17.2  74 . 6 11.1  47.1 16.2  43.7 17.9  40.13 17.9  35.5 20.1  LRB SRB PB FB  Long r a d i u s , f o o t b e d Short r a d i u s , footbed Pain, footbed Fatigue, footbed  66  -  Long r a d i u s , b o o t Short r a d i u s , boot P a i n , boot F a t i g u e , boot  FB 40 43 44 64 40 84 11 70 58 62 49 56 27 31 52 48.7 18.3  T a b l e G-2 A n a l y s i s o f V a r i a n c e - R a t i n g s f o r Edge C o n t r o l , F a t i g u e , Boot v s . Footbed Source  and  Mean Squares  DF  F Ratio  Within Subjects LRF v s LRB 4 0 8 3 . 333 Error 2918. 667  4083.333 208.476  1 14  19 .587  0.001  SRF v s SRB Error  5 6 8 5 . 633 2 2 7 5 . 867  5685.633 162.562  1 14  34 . 975  0.000  PF v s PB Error  97. 200 2 6 2 3 . 800  97.200 187.414  1 14  0 .519  0.483  FF v s FB Error  1306. 800 1623. 200  1306.800 115.943  1 14  11 .271  0.005  LRF SRF PF FF  -  Sum o f Squares  Pain,  Long r a d i u s , f o o t b e d Short radius, footbed Pain, footbed Fatigue, footbed  LRB SRB PB FB  67  -  Long r a d i u s , boot Short r a d i u s , boot Pain, boot Fatigue, boot  APPENDIX H COMPLETE RACE DATA. Table H-l R a c e R e s u l t s , A v e r a g e o f Two Runs  Mean SD  Footbed 17.145 17.19 16.115 17.5 17.685 18.585 20.235 19.55 18.315 17.32 16.4 16.365 18.435 17.39 18.21  Boot 17.45 17.47 16.735 17.785 17.99 18.585 20.535 19.78 18.7 17.45 16.905 16.65 18.73 17.645 18.485  17.763 1.327  18.060 1.202  T a b l e H-2 A n a l y s i s o f V a r i a n c e - Race R e s u l t s , Source Within B vs F Error  Sum o f Squares  Boot v s  Mean Squares  DF  F Ratio  p  0.662 0.010  1 14  66.420  0.000  Subjects 0.662 0.139  69  

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