"Education, Faculty of"@en . "Curriculum and Pedagogy (EDCP), Department of"@en . "DSpace"@en . "UBCV"@en . "MacIntyre, Donna Lee"@en . "2010-07-12T00:33:51Z"@en . "1986"@en . "Master of Education - MEd"@en . "University of British Columbia"@en . "The aim of this study was to determine if there was a difference in the surface EMG patterns of three of the quadriceps muscles (vastus medial is, vastus lateralis and rectus femoris) in female runners diagnosed with patellofemoral pain syndrome (PFPS) compared to the quadriceps activity of female runners free of knee pain and with normal lower extremity alignment.\r\nLinear envelope EMGs from vastus medial is, vastus lateralis and rectus femoris, together with a footswitch signal, were digitally recorded as each subject ran on a treadmill at 12 km/h. Each stride period was normalized to 100%, and then the linear envelopes for ten trials from each muscle were ensemble averaged to achieve a mean ensemble for each muscle from each subject. Subsequently, the grand mean ensemble of each muscle for all of the subjects in each group was computed.\r\nIt was also the objective of this study to determine if there was a difference in the peak concentric and eccentric torques of the quadriceps and the hamstrings between the experimental group and the control group. The subjects were tested on an isokinetic dynamometer (KINCOM) through a range of 90\u00B0 at an angular velocity of 200\u00B0/s.\r\nThe results showed no statistically significant differences between the groups for the peak EMG amplitudes. In fact when comparing the EMG patterns of activity between the two groups, the grand ensemble average of the experimental group remained within \u00B1 one standard deviation of the control group's mean EMG pattern. However, when individual subjects with PFPS were compared to the control group, there were periods in the gait cycle when the EMG amplitude was outside of \u00B1 one standard deviation of the control group's mean.\r\nWhen comparing the two groups for the peak concentric and eccentric torques of each muscle group, again the results were not statistically significant. The peak torques were also compared between groups as hamstrings/quadriceps ratios but found to be not significantly different. However, the mean concentric hamstrings/quadriceps ratio of the group with PFPS was found to be 1.02, which is outside of the range of values reported in the literature."@en . "https://circle.library.ubc.ca/rest/handle/2429/26353?expand=metadata"@en . "QUADRICEPS MUSCLE ACTIVITY IN FEMALE RUNNERS WITH PATELLOFEMORAL PAIN SYNDROME by DONNA LEE MACINTYRE B.S.R., The University of British Columbia, 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION in THE FACULTY OF GRADUATE STUDIES School of Physical Education and Recreation He accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA July 1986 \u00C2\u00AE Donna Lee Maclntyre, 1986 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of pHi^icAu \u00C2\u00A3DnCA)'0O The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date (Dot E-6 (3/81) ABSTRACT The a im o f t h i s s t u d y was t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n t h e s u r f a c e EMG p a t t e r n s o f t h r e e o f t h e q u a d r i c e p s m u s c l e s ( v a s t u s med i a l i s , v a s t u s l a t e r a l i s and r e c t u s f e m o r i s ) i n f e m a l e r u n n e r s d i a g n o s e d w i t h p a t e l l o f e m o r a l p a i n syndrome (PFPS) compared t o t h e q u a d r i c e p s a c t i v i t y o f f e m a l e r u n n e r s f r e e o f knee p a i n and w i t h norma l l o w e r e x t r e m i t y a l i g n m e n t . L i n e a r e n v e l o p e EMGs f r om v a s t u s m e d i a l i s , v a s t u s l a t e r a l i s and r e c t u s f e m o r i s , t o g e t h e r w i t h a f o o t s w i t c h s i g n a l , were d i g i t a l l y r e c o r d e d as each s u b j e c t r an on a t r e a d m i l l a t 12 km/h . Each s t r i d e p e r i o d was n o r m a l i z e d t o 100%, and t hen t h e l i n e a r e n v e l o p e s f o r t e n t r i a l s f r om each mus c l e were ensemb le a v e r aged t o a c h i e v e a mean ensemb le f o r each mus c l e f r om each s u b j e c t . S u b s e q u e n t l y , t h e g r and mean ensemb le o f each mus c l e f o r a l l o f t h e s u b j e c t s i n each g roup was computed . I t was a l s o t h e o b j e c t i v e o f t h i s s t u d y t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n t h e peak c o n c e n t r i c and e c c e n t r i c t o r q u e s o f t h e q u a d r i c e p s and t h e h a m s t r i n g s between t h e e x p e r i m e n t a l g roup and t h e c o n t r o l g r o u p . The s u b j e c t s were t e s t e d on an i s o k i n e t i c dynamometer (KINCOM) t h r o u g h a range o f 90\u00C2\u00B0 a t an a n g u l a r v e l o c i t y o f 200\u00C2\u00B0/s. The r e s u l t s showed no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e s between t h e g roups f o r t h e peak EMG a m p l i t u d e s . In f a c t when c ompa r i n g t h e EMG p a t t e r n s o f a c t i v i t y between t h e two g r o u p s , t h e g r and ensemb le a ve r age o f i n the experimental group remained within + one standard deviation of the control group's mean EMG pattern. However, when individual subjects with PFPS were compared to the control group, there were periods 1n the gait cycle when the EMG amplitude was outside of + one standard deviation of the control group's mean. When comparing the two groups for the peak concentric and eccentric torques of each muscle group, again the results were not s t a t i s t i c a l l y significant. The peak torques were also compared between groups as hamstrings/quadriceps ratios but found to be not significantly different. However, the mean concentric hamstrings/quadriceps ratio of the group with PFPS was found to be 1.02, which is outside of the range of values reported 1n the literature. TABLE OF CONTENTS A b s t r a c t i i L i s t o f T a b l e s v i L i s t o f F i g u r e s v i i Acknowl edgements v i i i I n t r o d u c t i o n 1 Pu r po s e 3 Me thodo l ogy 4 S u b j e c t s 4 E x p e r i m e n t a l P r o c e d u r e 5 T e s t i n g o f M u s c l e S t r e n g t h 5 EMG Measurement 7 S t a t i s t i c a l A n a l y s i s 8 R e s u l t s 10 D i s c u s s i o n 21 Group Mean M u s c l e A c t i v a t i o n P a t t e r n s 21 Peak C o n c e n t r i c and E c c e n t r i c To rque V a l u e s 24 C o n c l u s i o n s 31 Recommendat ions 33 V R e f e r e n c e s 34 Append i x 1 C h a r a c t e r i s t i c s o f t h e C o n t r o l Group S u b j e c t s and T h e i r I n d i v i d u a l Ensemb le A v e r a g e s 39 Append i x 2 I n d i v i d u a l Peak To rque V a l u e s and H a m s t r i n g s / Q u a d r i c e p s R a t i o s 53 Append i x 3 I n d i v i d u a l M u s c l e A c t i v a t i o n P a t t e r n s 55 Append i x 4 Rev iew o f t h e L i t e r a t u r e 81 P a t e l l o f e m o r a l P a i n Syndrome 82 I n t r o d u c t i o n 82 Anatomy o f t h e P a t e l l o f e m o r a l J o i n t 82 B i o m e c h a n i c s o f t h e P a t e l l o f e m o r a l J o i n t 85 C l i n i c a l F e a t u r e s 86 E t i o l o g y o f P a t e l l o f e m o r a l P a i n 90 E l e c t r o m y o g r a p h y 95 B i o m e c h a n i c a l S t u d i e s o f Runn i ng 98 I s o k i n e t i c Dynamometry 101 B i b l i o g r a p h y v i LIST OF TABLES I . D e s c r i p t i v e C h a r a c t e r i s t i c s o f t h e S u b j e c t s 10 I I . Summary o f Manova 14 EMG Peak A m p l i t u d e f o r V a s t u s M e d i a l i s , V a s t u s L a t e r a l i s and R e c t u s F e m o r i s I I I . Summary o f T - T e s t 15 IV . Mean Peak To rque V a l u e s a t 200\u00C2\u00B0/s 16 f o r t h e R i g h t Q u a d r i c e p s and H a m s t r i n g s V . Summary o f Manova 17 Peak To rque V a l u e s - Group by M u s c l e by C o n t r a c t i o n V I . Summary o f T - T e s t 18 Peak To rque - A n a l y s i s by R a t i o s V I I . D e v i a t i o n s o f t h e EMG A m p l i t u d e s Compared t o t h e 20 C o n t r o l G r o u p ' s G rand Ensemb le Ave r age V I I I . C l i n i c a l C h a r a c t e r i s t i c s o f t h e C o n t r o l Group S u b j e c t s 39 I X . I n d i v i d u a l Peak To rque V a l u e s f o r t h e R i g h t Leg a t 200\u00C2\u00B0/s. .53 X . I n d i v i d u a l C o n c e n t r i c and E c c e n t r i c H a m s t r i n g s / 54 Q u a d r i c e p s R a t i o s f o r t h e R i g h t Leg X I . C l i n i c a l C h a r a c t e r i s t i c s and Dynamic S t r e n g t h o f 55 Those S u b j e c t s W i t h R i g h t P a t e l l o f e m o r a l P a i n Syndrome v i i LIST OF FIGURES 1. Grand Ensemb le Ave r age s o f t h e C o n t r o l Group 11 2 . Grand Ensemble A v e r a g e s o f t h e E x p e r i m e n t a l Group 12 3 . G rand Ensemble Ave r age s o f t h e E x p e r i m e n t a l Group 13 Compared t o t h e C o n t r o l Group 4 . S u b j e c t CR 41 5 . S u b j e c t CS 42 6 . S u b j e c t GG 43 7 . S u b j e c t J F 44 8 . S u b j e c t LS 45 9 . S u b j e c t MR 46 1 0 . S u b j e c t PB 47 1 1 . S u b j e c t PW 48 1 2 . S u b j e c t SL 49 1 3 . S u b j e c t SO 50 1 4 . S u b j e c t SP 51 1 5 . S u b j e c t VA 52 1 6 . S u b j e c t SC 58 1 7 . S u b j e c t HB 61 1 8 . S u b j e c t EC 64 1 9 . S u b j e c t TR 67 2 0 . S u b j e c t RW 69 2 1 . S u b j e c t SS 71 2 2 . S u b j e c t JH 75 2 3 . S u b j e c t JG 77 v i i i ACKNOWLEDGEMENTS I wou l d l i k e t o e x p r e s s my a p p r e c i a t i o n t o D r . D. Gordon E. R o b e r t s o n f o r h i s g u i d a n c e , p a t i e n c e and encou ragement t h r o u g h o u t t h e c o u r s e o f my t h e s i s w o r k . I am a l s o g r a t e f u l t o D r . ' s Don M c K e n z i e , J a c k Taun ton and J e a n Wesse l f o r t h e i r s u p p o r t and a s s i s t a n c e w i t h o u t w h i c h I wou l d n o t have been a b l e t o c o m p l e t e t h i s s t u d y . F i n a l l y , I w i s h t o thank my f a m i l y and f r i e n d s who i n d i r e c t l y and o f t e n u n k n o w i n g l y have p r o v i d e d me w i t h u n d e r s t a n d i n g and t h e i n c e n t i v e t o c o m p l e t e what somet imes seemed l i k e an i m p o s s i b l e t a s k ! - 1 -INTRODUCTION The d r a m a t i c i n c r e a s e i n t h e p o p u l a r i t y o f e x e r c i s e , and i n p a r t i c u l a r r u n n i n g , i n t h e p a s t few decades has p r odu ced a need t o u n d e r s t a n d t h e b i o m e c h a n i c s o f r u n n i n g so t h a t e l i t e a t h l e t e s can improve t h e i r p e r f o r m -ances and c l i n i c i a n s can t r e a t and pe rhaps p r e v e n t r u n n i n g i n j u r i e s . T h i s need i s c o m p l i c a t e d by t h e f a c t t h a t t h e r e may be more v a r i a b i l i t y i n t h e mechan i c s o f r u n n i n g t h a n i n w a l k i n g . Mann (1982) s u g g e s t s t h a t speed i s one o b v i o u s v a r i a b l e w h i c h a f f e c t s r ange o f m o t i o n , m u s c l e a c t i v i t y and j o i n t f o r c e s i n t h e l o w e r e x t r e m i t y . However , i f t h e r u n n i n g speed c an be h e l d c o n s t a n t by a t r e a d m i l l , t h en a f a c t o r such as p h a s i c mus c l e a c t i v i t y can be s t u d i e d and compared between g r oups o f s u b j e c t s . Our s o c i e t y ' s i n c r e a s e d p a r t i c p a t i o n i n p h y s i c a l a c t i v i t y has a l s o r e s u l t e d i n an a s s o c i a t e d r i s e i n o v e r u s e i n j u r i e s . Ma lek and Mang ine (1981) and C l emen t e t a l . (1981) have f ound f r om t h e i r r e v i e w o f c l i n i c a l r e c o r d s t h a t t h e most common s i t e o f i n j u r y i s t h e knee and t h e most common c l i n i c a l f i n d i n g i s p a t e l l o f e m o r a l p a i n syndrome ( P F P S ) . P a t e l l o f e m o r a l p a i n syndrome has been d e s c r i b e d as a d i f f u s e , p o o r l y l o c a t e d p a i n a r ound t h e p a t e l l a w h i c h a r i s e s f r om abnormal t r a c k i n g o f t h e p a t e l l a (G rana e t a l . 1 9 8 4 ) . A n a t o m i c a l f a c t o r s w h i c h have been i d e n t i f i e d as h a v i n g some i n f l u e n c e on t h e a l i g n m e n t o f t h e p a t e l l a a r e genu v a l g um , genu r e c u r v a t u m , p a t e l l a a l t a , a h y p e r m o b i l e p a t e l l a , f emo r a l neck a n t e v e r s i o n , p r o n a t e d f e e t , i n e f f i c i e n c y o f t h e v a s t u s m e d i a l i s mus c l e a n d / o r h y p e r t r o p h y o f t h e v a s t u s l a t e r a l i s ( R e y n o l d s e t a l . 1 9 8 3 ) . - 2 -The e l e c t r o m y o g r a p h i c a c t i v i t y o f t h e m u s c l e s of t h e k n e e , i n p a r t i c u l a r t h e q u a d r i c e p s have been s t u d i e d i n i s o m e t r i c c o n t r a c t i o n s ( H a l l e n and L i n d a h l , 1967; L i e b and P e r r y , 1 9 7 1 ) , i n a c t i v e and r e s i s t e d mus c l e work ( P o c o c k , 1963; E l o r a n t a and K o m i , 1 9 8 1 ) , d u r i n g e c c e n t r i c and c o n c e n t r i c work ( K o m i , 1 9 7 3 ) , and d u r i n g t h e l a s t 30\u00C2\u00B0 o f e x t e n s i o n w h i l e w e i g h t - b e a r i n g ( R e y n o l d s e t a l , 1 9 8 3 ) . The n e x t l o g i c a l p r o g e s s i o n of musc l e a n a l y s i s p a r t i c u l a r t o r u n n i n g has been t o a n a l y z e t h e mus c l e a c t i v i t y d u r i n g a c t u a l r u n n i n g u s i n g EMG ( E l l i o t t and B l a n k s b y , 1979; Schwab e t a l . 1983; M a c l n t y r e and R o b e r t s o n , i n p r e s s ) . Improvements i n e l e c t r i c a l t e c h n o l o g y i n t h e p a s t few decades have made p o s s i b l e advancements i n e l e c t r o m y o g r a p h i c a n a l y s i s of g a i t . Th rough EMG s t u d i e s o f w a l k i n g , a b a s e l i n e of normal moto r p a t t e r n s has been e s t a b l i s h e d and s p e c i f i c a b n o r m a l i t i e s can be d e t e c t e d when compared t o t h e norm ( W i n t e r , 1 9 8 4 ) . U t i l i z i n g t h e s e same t e c h n i q u e s , i t i s a l s o p o s s i b l e t o s t u d y t h e p a t t e r n s of m u s c l e a c t i v i t y i n r u n n i n g and t o d e t e r m i n e i f t h e r e a r e o b s e r v a b l e a b n o r m a l i t i e s i n c e r t a i n c l i n i c a l c o n d i t i o n s . Re cen t advancements i n mus c l e t e s t i n g t e c h n i q u e s , i n p a r t i c u l a r t h e deve l opmen t of an i s o k i n e t i c dynamometer wh i c h can a s s e s s c o n c e n t r i c and e c c e n t r i c m u s c l e s t r e n g t h , have made i t p o s s i b l e t o r e l a t e m u s c l e s t r e n g t h r e s u l t s w i t h f u n c t i o n a l a c t i v i t y . I t has been shown by W i n t e r (1983) t h a t o v e r one r u n n i n g s t r i d e t h e knee m u s c l e s a b s o r b a p p r o x i m a t e l y t h r e e and a h a l f t i m e s more ene rgy t h a n t h e y g e n e r a t e , w i t h t h e l a r g e s t amount of e c c e n t r i c a c t i v i t y i n t h e q u a d r i c e p s d u r i n g s t a n c e p h a s e . The i m p o r t a n c e of h i s f i n d i n g s d u r i n g r u n n i n g r e l a t e s t o t h e use of t h e i s o k i n e t i c - 3 -dynamometer and t he need t o be a b l e t o t e s t and t r a i n m u s c l e s d u r i n g c o n c e n t r i c and e c c e n t r i c c o n t r a c t i o n s . Purpose The pu rpo se o f t h i s s t u dy was t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e i n t h e EMG p a t t e r n s o f t h e q u a d r i c e p s i n f e m a l e r u n n e r s w i t h p a t e l l o -f emo ra l p a i n syndrome compared t o a g roup o f f e m a l e r u n n e r s f r e e o f knee p a i n and w i t h normal l o w e r e x t r e m i t y a l i g n m e n t . S e c o n d a r i l y , t h i s s t u d y compared t h e peak c o n c e n t r i c and e c c e n t r i c t o r q u e o f t h e q u a d r i c e p s and h a m s t r i n g s a t an a n g u l a r v e l o c i t y o f 200\u00C2\u00B0/s t o see i f t h e r e was a s i g n i f i c a n t d i f f e r e n c e between t h o s e g roups o f s u b j e c t s w i t h and w i t h o u t p a t e l l o f e m o r a l p a i n syndrome. - 4 -METHODOLOGY SUBJECTS Twenty f e m a l e r e c r e a t i o n a l r u n n e r s , aged 15-36 y e a r s , v o l u n t e e r e d t o t a k e p a r t i n t h i s s t u d y . Twe l ve o f t h e s u b j e c t s were p l a c e d i n t h e c o n t r o l g roup as t h e y had no c o m p l a i n t s o f knee p a i n , no p r e v i o u s l o w e r e x t r e m i t y s u r g e r y o r known m u s c u l o s k e l e t a l a b n o r m a l i t i e s , and ' n o r m a l ' l o w e r e x t r e m i t y a l i g n m e n t . They were e v a l u a t e d by t h e p h y s i c i a n s a t U . B . C . S p o r t s M e d i c i n e C l i n i c f o r Q -ang l e (S chambe rge r , 1 9 8 3 ) , r e a r f o o t and f o r e f o o t a l i g n m e n t ( J ames , 1 9 7 9 ) , t h e deg ree o f p r o n a t i o n (James e t a l . 1 9 7 8 ) , l e g l e n g t h , and a l i g n m e n t a t t h e knee (Lehmkuhl and S m i t h , 1 9 8 3 ) . Normal v a l u e s were c o n s i d e r e d t o be : Q -ang l e 15\u00C2\u00B0 o r l e s s , r e a r f o o t and f o r e f o o t v a r u s 4\u00C2\u00B0 o r l e s s , no o v e r p r o n a t i o n , l e g l e n g t h d i s c r e p a n c y l e s s t h a n one c e n t i m e t e r and no genu r e c u r v a t u m . These s u b j e c t s were r u n n i n g a t l e a s t 16 km/week (10 m i l e s / w e e k ) . The e x p e r i m e n t a l g roup c o n s i s t e d o f e i g h t s u b j e c t s who had been d i a g n o s e d as h a v i n g p a t e l l o f e m o r a l p a i n syndrome by t h e p h y s i c i a n s a t UBC S p o r t s M e d i c i n e C l i n i c . They c o m p l a i n e d o f r i g h t knee p a i n a r ound t h e p a t e l l a , and had t h e f o l l o w i n g l o w e r e x t r e m i t y m a l a l i g n m e n t f e a t u r e s : Q - ang l e 15\u00C2\u00B0 o r more , r e a r f o o t and f o r e f o o t a l i g n m e n t measures more t h a n 4\u00C2\u00B0 and o v e r p r o n a t i o n o f t h e r i g h t f o o t when w e i g h t - b e a r i n g . F u r t h e r m o r e t h e i r l e g l e n g t h and a l i g n m e n t a t t h e knee were a s s e s s e d . These s u b j e c t s were a l s o r u n n i n g p r i o r t o t h e o n s e t o f p a i n . - 5 -EXPERIMENTAL PROCEDURE Testing of Peak Torque The s u b j e c t s were t e s t e d on an i s o k i n e t i c dynamometer (KINCOM) t o d e t e r m i n e t h e peak t o r q u e o f t h e i r r i g h t q u a d r i c e p s and h a m s t r i n g s , d u r i n g f o u r c o n c e n t r i c and e c c e n t r i c c o n t r a c t i o n s . I l l u s t r a t i o n o f a s u b j e c t b e i n g t e s t e d f o r q u a d r i c e p s s t r e n g t h on t h e KINCOM. Each s u b j e c t was i n s t r u c t e d t o s i t w i t h h e r back a g a i n s t t h e back s u p p o r t o f t h e c h a i r , t h e p e l v i s was s t a b i l i z e d by s t r a p p i n g , and t he p o s t e r i o r a s p e c t o f t h e knee was p o s i t i o n e d a t t h e f r o n t o f t h e c h a i r . - 6 -P o s i t i o n i n g o f t h e s u b j e c t ' s l o w e r l e g a g a i n s t t h e f o r c e arm o f t h e mach ine f o l l o w e d t h e d i r e c t i o n o f G o s l i n and C h a r t e r i s ( 1 9 7 9 ) . S u b j e c t s were i n s t r u c t e d t o g r i p t h e s i d e s o f t h e s e a t f o r s u p p o r t d u r i n g t h e t e s t i n g . D u r i n g h a m s t r i n g s t e s t i n g a d d i t i o n a l s t a b i l i z a t i o n was p r o v i d e d by s t r a p p i n g t h e t h i g h t o t h e t a b l e . The s u b j e c t s were g i v e n s t a n d a r d i z e d i n s t r u c t i o n s and t hen f o u r submaximal t r i a l s were p e r f o rmed b e f o r e t h e maximal t e s t . The range o f m o t i o n f o r t h e knee movement was t h r o u g h an a r c o f 90\u00C2\u00B0 (5\u00C2\u00B0 - 95\u00C2\u00B0) a t a v e l o c i t y o f 200\u00C2\u00B0/s, n o n - g r a v i t y c o r r e c t e d . Each t e s t c o n s i s t e d o f a c o n c e n t r i c c o n t r a c t i o n and an e c c e n t r i c c o n t r a c t i o n , t h u s , t h e s u b j e c t had t o c o n c e n t r a t e on two c o n s e c u t i v e c o n t r a c t i o n s f o r each r e p e t i t i o n . Each s u b j e c t p e r f o rmed f o u r max imal r e p e t i t i o n s f o r each mus c l e g roup ( q u a d r i c e p s and h a m s t r i n g s ) w i t h v e r b a l en cou ragemen t . EMG Measurement The s u b j e c t s r a n on a t r e a d m i l l , f i r s t a t a speed t h a t was 80% o f t h e i r normal r u n n i n g pace and t h e n f o r a s e cond t r i a l a t 12 km/h ( 7 . 5 MPH) u n t i l 10 s t r i d e s were c o l l e c t e d by t h e c ompu t e r . The f i r s t t r i a l was used as a warm-up f o r t h e se cond r un a t 12 km/h . L i n e a r e n v e l o p e EMG s i g n a l s f r om t h e r i g h t v a s t u s m e d i a l i s , v a s t u s l a t e r a l i s and r e c t u s f e m o r i s , t o g e t h e r w i t h a f o o t s w i t c h s i g n a l , were d i g i t a l l y r e c o r d e d a t 100 Hz e a c h . S u r f a c e e l e c t r o d e s were p l a c e d o v e r t h e mo to r p o i n t s o f each o f t h e m u s c l e s ( D e l a g i e t a l . 1 9 7 5 ) , w i t h an i n t e r e l e c t r o d e s p a c i n g o f one c e n t i m e t e r . P r e p a r a t i o n o f t h e s k i n was a c c o r d i n g t o t h e methods d e s c r i b e d by B a s m a j i a n ( 1 9 7 9 ) . - 7 -I l l u s t r a t i o n o f a s u b j e c t r u n n i n g on t h e t r e a d m i l l w i t h s u r f a c e e l e c t r o d e s i n p l a c e . The b i o a m p l i f i e r (custom-made) had a f r e q u e n c y r ange o f 20-1000 H z , t h e g a i n was 1000, t h e i n p u t impedance was 10 megaohms and t h e common mode r e j e c t i o n r a t i o (CMRR) was g r e a t e r t h an 100 dB . The a m p l i f i e r u t i l i z e d a se cond o r d e r band -pa s s f i l t e r ( W i n t e r , p e r s o n a l c o m m u n i c a t i o n ) . Each s t r i d e p e r i o d was n o r m a l i z e d t o 100% and t hen ensemb le a v e r a g e d o v e r t h e 10 t r i a l s f o r each mus c l e and f o r each s u b j e c t by c o m p u t e r . - 8 -S t a n d a r d d e v i a t i o n s f o r each i n t e r v a l were a l s o c a l c u l a t e d . S u b s e q u e n t l y g r and ensemb le a v e r a g e s f o r each mus c l e and f o r a l l o f t h e s u b j e c t s i n each g roup were compu ted . Statistical Analysis A m u l t i v a r i a t e a n a l y s i s (MANOVA) was done t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e between g r oups f o r t h e peak EMG a m p l i t u d e f r om each mus c l e ( v a s t u s m e d i a l i s , v a s t u s l a t e r a l i s and r e c t u s f e m o r i s ) d u r i n g s t a n c e . A s e cond MANOVA a n a l y s i s was p e r f o rmed t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e between g roups f o r mus c l e s t r e n g t h (peak t o r q u e s ) i n t h e q u a d r i c e p s and h a m s t r i n g s , bo th c o n c e n t r i c a l l y and e c c e n t r i c a l l y . An a n a l y s i s o f t h e s t r e n g t h r e l a t i o n s h i p s between t h e q u a d r i c e p s and h a m s t r i n g s , as e x p r e s s e d as a r a t i o , was done by a t - t e s t t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e between g r o u p s . The l e v e l f o r s i g n i f i c a n c e o f ea ch a n a l y s i s was s e t a t p < 0 . 0 5 . A v i s u a l a n a l y s i s o f t h e EMG d a t a was a l s o i n c l u d e d t o d e t e r m i n e i f t h e r e was a d i f f e r e n c e o f more t h a n _+ one s t a n d a r d d e v i a t i o n i n t h e p h a s i c p a t t e r n s o f t h e mus c l e a c t i v i t y when t h e e x p e r i m e n t a l g roup was compared t o t h e c o n t r o l g r o u p . F u r t h e r m o r e , each i n d i v i d u a l ' s EMG p r o f i l e was s upe r impo sed on t h e c o n t r o l g r o u p ' s g r and ensemb le a v e r age t o d e t e r m i n e i f t h e r e were d i f f e r e n c e s o f more t han + one s t a n d a r d d e v i a t i o n , i n t h e i r EMG p a t t e r n s . - 9 -RESULTS T a b l e I i s a summary o f t h e c h a r a c t e r i s t i c s and c l i n i c a l f i n d i n g s o f t h e s u b j e c t s i n each g r o u p . TABLE I D e s c r i p t i v e C h a r a c t e r i s t i c s o f t h e S u b j e c t s AGE ( r a n g e ) HEIGHT ( r a n g e ) WEIGHT ( r a n g e ) KM/WEEK ( r ange ) KNEE PAIN Q-ANGLE REARFOOT & FOREFOOT ALIGNMENT OVERPRONATION (n) C o n t r o l Group 12 20 - 32 y e a r s 155 cm - 175 cm 5 3 . 2 - 6 3 . 6 kg 19 - 56 No 15\u00C2\u00B0 o r l e s s 4\u00C2\u00B0 o r l e s s 4 m i l d E x p e r i m e n t a l Group 8 15 - 36 y e a r s 152 .5 cm - 167 . 5 cm 50 kg - 6 3 . 6 kg 8 - 4 0 Yes 15\u00C2\u00B0 o r more 4\u00C2\u00B0 o r more - 10 -F i g u r e 1 shows t h e g r and ensemb le a v e r a g e s o f each m u s c l e ' s EMG a c t i v i t y ( V . M . - v a s t u s m e d i a l i s , R . F . - r e c t u s f e m o r i s , V . L . - v a s t u s l a t e r a l i s ) f r om t h e 12 s u b j e c t s i n t h e c o n t r o l g r o u p . The s o l i d l i n e r e p r e s e n t s t h e g r and ensemb le a v e r age w h i l e t h e d o t t e d l i n e s a r e + one s t a n d a r d d e v i a t i o n . One hund red p e r c e n t o f t h e g a i t c y c l e i s f r om h e e l -s t r i k e t o i p s i l a t e r a l hee l s t r i k e . T o e - o f f o c c u r r e d between 29 and 45% o f t h e c y c l e . The a m p l i t u d e o f t h e c u r v e s i s measured i n m i l l i v o l t s . The g r and ensemb le a v e r a g e s o f v a s t u s m e d i a l i s and r e c t u s f e m o r i s r e p r e s e n t 11 EMG p r o f i l e s . The re were t e n EMG r e c o r d i n g s o b t a i n e d f o r t h e g r and ensemb le a v e r a g e o f v a s t u s l a t e r a l i s . F i g u r e 2 r e p r e s e n t s t h e g r and ensemb le a v e r a g e s o f each m u s c l e f o r t h e e i g h t s u b j e c t s i n t h e e x p e r i m e n t a l g r o u p . T o e - o f f o c c u r r e d between 30 and 50% o f t h e g a i t c y c l e . In t h e e x p e r i m e n t a l g r o u p , t h e r e were a t o t a l o f e i g h t EMG p r o f i l e s each f o r v a s t u s m e d i a l i s and v a s t u s l a t e r a l i s , w h i l e t h e number o f r e c o r d i n g s f o r r e c t u s f e m o r i s was s e v e n . F i g u r e 3 shows t h e g r and ensemb le a v e r age o f each m u s c l e f r om t h e e x p e r i m e n t a l g roup s upe r imposed on t h e r e s u l t s o f t h e c o n t r o l g r o u p . The s o l i d l i n e i s t h e g r and ensemb le a ve r age o f t h e c o n t r o l g r o u p , t h e d o t t e d l i n e s r e p r e s e n t ^ one s t a n d a r d d e v i a t i o n o f t h e c o n t r o l g r o u p ' s mean, and t h e c r o s s e d l i n e i s t h e g r and ensemb le a v e r age o f t h e e x p e r i m e n t a l g r o u p . 0 . 6 0 . 5 > \u00C2\u00A3 0 . 4 0 . 3 _ J 0 . 2 > 0 . 1 0 . 0 0 6 0 5 > \u00C2\u00A3 0 4 0 3 0 2 cn 0 . 1 0 . 0 0 . 6 0 . 5 > \u00C2\u00A3 0 . 4 0 . 3 0 . 2 > 0 . 1 0 . 0 FIGURE 1 GRAND ENSEMBLE AVERAGES OF THE CONTROL GROUP \"1 1 1 ' I I \u00E2\u0080\u00A2I I \"1 1 2 0 3 0 4 0 5 0 6 0 % C Y C L E - 1 1 1^ 1 7 0 8 0 9 0 1 0 0 FIGURE 2 GRAND ENSEMBLE AVERAGES OF THE EXPERIMENTAL GROUP 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 % C Y C L E 0 . 6 _ FIGURE 3 GRAND ENSEMBLE AVERAGES OF THE EXPERIMENTAL GROUP COMPARED TO THE CONTROL GROUP 4 0 5 0 6 0 % C Y C L E C O I 1 0 0 - 14 -A m u l t i v a r i a t e a n a l y s i s (MANOVA) o f t h e peak EMG a m p l i t u d e s o f each mus c l e d u r i n g s t a n c e showed no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e between g r o u p s , and no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e when t h e v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s were compa red . However , t h e a n a l y s i s d i d r e v e a l a 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 peak a m p l i t u d e s o f r e c t u s f e m o r i s and t h e v a s t u s l a t e r a l i s and a s i g n i f i c a n t d i f f e r e n c e between r e c t u s f e m o r i s and t h e v a s t u s m e d i a l i s (p < 0 . 0 5 ) . TABLE II Summary o f Manova EMG Peak A m p l i t u d e f o r V a s t u s M e d i a l i s , V a s t u s L a t e r a l i s and R e c t u s F e m o r i s C o n t r o l Group v s E x p e r i m e n t a l Group d f 1,13 Between Groups N .S . (p = .114) Between M u s c l e s V a s t u s L a t e r a l i s / R e c t u s F e m o r i s p = .008 V a s t u s M e d i a l i s ^Rec tus F e m o r i s p = .007 V a s t u s M e d i a l i s ^Vas tu s L a t e r a l i s N. S . (p = .347) - 15 -S u b s e q u e n t l y , a t - t e s t was p e r f o r m e d f o r each mus c l e t o d e t e r m i n e i f t h e r e wou l d have been a s i g n f i c a n t d i f f e r e n c e between t h e c o n t r o l g roup and t h e e x p e r i m e n t a l g roup peak EMG a m p l i t u d e s i f o n l y one mus c l e had been t e s t e d i n t h e e x p e r i m e n t . TABLE III Summary o f T - t e s t V a s t u s M e d i a l i s C o n t r o l Group \"x = 309 .18 d f = 17 t = 1.241 N .S . E x p e r i m e n t a l Group 7 = 238 .87 V a s t u s L a t e r a l i s C o n t r o l Group x = 457 . 40 d f = 16 t = 2 .196 p < .025 E x p e r i m e n t a l Group \"x = 289 .87 R e c t u s F e m o r i s C o n t r o l Group x = 142 .82 d f = 16 t = 0 .244 N .S . E x p e r i m e n t a l Group \"x = 137 I f v a s t u s l a t e r a l i s had been t h e o n l y mus c l e t e s t e d t h e r e wou l d have been a 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 peak EMG a m p l i t u d e s o f t h e two g roups (p < 0 . 0 5 ) . - 16 -In T a b l e IV t h e r e s u l t s o f t h e m u s c l e s t r e n g t h t e s t s on t h e i s o k i n e t i c dynamometer a r e s ummar i z ed . TABLE IV Mean Peak To rque V a l u e s (+ one s t a n d a r d d e v i a t i o n ) a t 200\u00C2\u00B0/s f o r t h e R i g h t Q u a d r i c e p s and H a m s t r i n g s C o n t r o l Group (n=12) E x p e r i m e n t a l Group (n=8) Q u a d r i c e p s E c c e n t r i c C o n c e n t r i c 170 N.m 112 .6 N.m (+50 .33) (+22 .27 ) 139 .4 N.m 9 5 . 1 N.m (+47 .06) (+21 .36) H a m s t r i n g s E c c e n t r i c C o n c e n t r i c 116 .25 N.m 9 8 . 5 N.m (+26 .53 ) (+21 .85) 111 .4 N.m (+27 .25) 93.6- N.m (+17 .94) - 17 -T a b l e V i s a summary o f t h e m u l t i v a r i a t e a n a l y s i s o f t h e mean peak t o r q u e s when compared by g r o u p s , by m u s c l e s ( q u a d r i c e p s and h a m s t r i n g s ) and by c o n t r a c t i o n ( e c c e n t r i c and c o n c e n t r i c ) . TABLE Y Summary o f Manova Peak To rque V a l u e s - Group by M u s c l e by C o n t r a c t i o n d f 1, 18 Between Groups N .S . (p = .230) Between M u s c l e s p = .001 Between C o n t r a c t i o n s p < .001 Peak t o r q u e v a l u e s were d e f i n e d as t h e h i g h e s t r e c o r d e d v a l u e on any one o f f o u r r e p e t i t i o n s o f t h e mus c l e t e s t , r e g a r d l e s s o f i t s p o s i t i o n i n t h e range o f m o t i o n . The re was no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e between t h e g r oups f o r t h e peak t o r q u e v a l u e s , a l t h o u g h t h e r e was a 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 peak t o r q u e s o f t h e h a m s t r i n g s and t h e q u a d r i c e p s when t hey were g r ouped by m u s c l e . The r e was a l s o 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 peak t o r q u e s o f c o n c e n t r i c and e c c e n t r i c c o n t r a c t i o n s . - 18 -H a m s t r i n g s / q u a d r i c e p s (H/Q) r a t i o s were c a l c u l a t e d f r om t h e peak t o r q u e v a l u e s o f b o t h t h e e c c e n t r i c and c o n c e n t r i c c o n t r a c t i o n s . T a b l e VI i s a summary o f t h e t - t e s t t o compare g r oups f o r each o f t h e r a t i o s . TABLE VI Summary o f T - t e s t Peak To rque - A n a l y s i s By R a t i o s H/Q RATIO CONCENTRIC CONTROL GROUP x = .88 d f = 18 t = - 1 . 6 0 N .S . (p = .127) EXPERIMENTAL GROUP x = 1.02 H/Q RATIO ECCENTRIC CONTROL GROUP x = .73 d f = 18 t = - 1 . 0 6 N .S . (p = .304) EXPERIMENTAL GROUP x = .87 The re was no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e between t h e g r oups f o r e i t h e r t h e c o n c e n t r i c o r e c c e n t r i c H/Q r a t i o s . - 19 -T a b l e V I I i s a summary o f t h e number o f d e v i a t i o n s o f t h e ensemb le a v e r a g e s o u t s i d e o f + one s t a n d a r d d e v i a t i o n o f t h e c o n t r o l g r o u p ' s mean, f o r t h e e x p e r i m e n t a l g roup and t h e c o n t r o l g r o u p . In a normal ( G a u s s i a n ) d i s t r i b u t i o n 68.26% o f t h e s u b j e c t s ' EMG p r o f i l e s w o u l d l i e w i t h i n + one s t a n d a r d d e v i a t i o n and 15.87% wou l d be above one s t a n d a r d d e v i a t i o n w h i l e 15.87% wou l d be l e s s t h an one s t a n d a r d d e v i a t i o n . To d e t e r m i n e i f t h e r e s u l t s o f t h e c o n t r o l g roup f o l l o w e d a normal d i s t r i b u t i o n , t h e EMG peak a m p l i t u d e s d u r i n g s t a n c e phase f o r a l l t h r e e m u s c l e s and sw i ng phase f o r r e c t u s f e m o r i s f r om each s u b j e c t i n t h e c o n t r o l g roup were compared t o t h e mean EMG p a t t e r n +_ one s t a n d a r d d e v i a t i o n . S u b s e q u e n t l y t h e same EMG a m p l i t u d e s f r om each s u b j e c t i n t h e e x p e r i m e n t a l g roup were compared t o t h e c o n t r o l g r o u p ' s g r and ensemb le a v e r age +_ one s t a n d a r d d e v i a t i o n t o d e t e r m i n e i f t h e r e were more d e v i a t i o n s ( o u t s i d e + one s t a n d a r d d e v i a t i o n ) i n t h e EMG p r o f i l e s o f t h e g roup o f s u b j e c t s w i t h p a t e l l o f e m o r a l p a i n syndrome t han one wou l d e x p e c t i n a normal d i s t r i b u t i o n . - 20 -TABLE VII Deviations of the EMG Peak Amplitudes Compared to the Control Group's Grand Ensemble Average V a s t u s m e d i a l i s ( s t a n c e phase) w i t h i n +_ 1 S . D . above 1 S . D . be low 1 S . D . C o n t r o l Group 6/11 * 3/11 2/11 E x p e r i m e n t a l Group 6/8 2/8 R e c t u s f e m o r i s ( s t a n c e phase) w i t h i n + 1 S . D . above 1 S . D . be low 1 S . D . 5/11 4 /11 2/11 4/7 2/7 1/7 ( sw i ng phase) w i t h i n + 1 S .D . above 1 S .D . be l ow 1 S .D . 6/11 3/11 2/11 2/7 5/7 V a s t u s l a t e r a l i s ( s t a n c e phase) w i t h i n + 1 S .D . above 1 S .D . be l ow 1 S .D . 6/10 2/10 2/10 4/8 4/8 S i x s u b j e c t s o u t o f 11 r ema i ned w i t h i n + one s t a n d a r d d e v i a t i o n ( S . D . ) - 21 -DISCUSSION Group Mean Muscle Activation Patterns The r e s u l t s o f t h e c o m p a r i s o n o f t h e g r a n d ensemb le a v e r a g e s o f t h e q u a d r i c e p s m u s c l e s ( t h e v a s t u s m e d i a l i s , r e c t u s f e m o r i s and t h e v a s t u s l a t e r a l i s ) o f s u b j e c t s w i t h p a t e l l o f e m o r a l p a i n syndrome t o t h o s e s u b j e c t s w i t h normal l o w e r e x t r e m i t y a l i g n m e n t and no knee p a i n , showed t h a t t h e two g r oups had t h e same a ve r age p a t t e r n s o f m u s c l e a c t i v i t y w h i l e r u n n i n g on a t r e a d m i l l , v a r y i n g o n l y i n r e g a r d t o a m p l i t u d e ( F i g u r e 3 ) . The peak a m p l i t u d e d i f f e r e n c e was n o t s t a t i s t i c a l l y s i g n i f i c a n t ( T a b l e I I ) as t h e mean mus c l e p a t t e r n s o f t h e e x p e r i m e n t a l g roup r ema i ned w i t h i n _+ one s t a n d a r d d e v i a t i o n o f t h e c o n t r o l g r o u p ' s mean. The mean m u s c l e p a t t e r n s r e v e a l e d t h a t t h e l a r g e s t amount o f q u a d r i c e p s a c t i v i t y o c c u r r e d i n e a r l y s t a n c e i n b o t h t h e c o n t r o l g roup and t he e x p e r i m e n t a l g r o u p . T h i s b u r s t o f a c t i v i t y c o i n c i d e s w i t h an ene rgy a b s o r b i n g phase by t h e knee e x t e n s o r s as t h e y a r e c o n t r a c t i n g e c c e n t r i c a l l y t o c o n t r o l knee f l e x i o n ( W i n t e r , 1983; R o b e r t s o n and T a u n t o n , 1982; R o b e r t s o n , i n p r e s s ) . W i n t e r (1983) and R o b e r t s o n ( i n p r e s s ) have a l s o r e p o r t e d f r om t h e i r power a n a l y s e s o f j o g g i n g and r u n n i n g , t h a t f r om m i d - s t a n c e u n t i l l a t e - s t a n c e t h e q u a d r i c e p s c o n t i n u e t o be a c t i v e b u t t h e y a r e c o n t r a c t i n g c o n c e n t r i c a l l y t o e x t e n d t h e k n e e . From t h e EMG r e s u l t s o f t h i s s t u d y i t wou l d appea r t h a t t h e v a s t u s med i a l i s and v a s t u s l a t e r a l i s c o n t r i b u t e most t o t h e a c t i v i t y o f t h e q u a d r i c e p s d u r i n g e a r l y s t a n c e , s i n c e r e c t u s f e m o r i s showed l e s s mus c l e a c t i v i t y a t t h i s t i m e i n t h e g a i t c y c l e . In t h e i r EMG s t u d y o f t h e l e g m u s c l e s d u r i n g t r e a d m i l l r u n n i n g , E l l i o t t and B l a n k s b y (1979) a l s o - 22 -r e p o r t e d t h e v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s t o have l a r g e r a m p l i t u d e s d u r i n g s t a n c e phase t h a n r e c t u s f e m o r i s , howeve r , t h e i r r e s u l t s d i f f e r e d f r om t h i s s t u d y i n t h a t t h e y r e p o r t e d t h e v a s t u s m e d i a l i s t o have t h e g r e a t e s t peak a m p l i t u d e w h i l e t h i s s t u d y f o u n d t h e v a s t u s l a t e r a l i s t o have t h e most EMG a c t i v i t y . I t i s n o t known why t h e r e may be t h e d i f f e r e n c e i n t h e a m p l i t u d e s o f t h e two m u s c l e s between t h e two s t u d i e s , as E l l i o t t and B l a n k s b y a l s o had t h e i r f e m a l e s u b j e c t s ( aged 20 -28 y e a r s ) r un on a t r e a d m i l l a t a p p r o x i m a t e l y 12 km/h . The m a j o r d i f f e r e n c e between t h e s t u d i e s i s t h a t E l l i o t t and B l a n k s b y u sed a v e r a g e d i n t e g r a t e d EMG as a f o rm o f p r o c e s s i n g w h i l e t h i s s t u d y u t i l i z e d l i n e a r e n v e l o p e p r o c e s s i n g . D u r i n g sw i ng p h a s e , t h e r e was a s e cond b u r s t o f a c t i v i t y i n r e c t u s f e m o r i s b u t no f u r t h e r a c t i v i t y i n t h e v a s t u s m e d i a l i s o r t h e v a s t u s l a t e r a l i s . E l l i o t t and B l a n k s b y (1979) a l s o r e p o r t e d t h i s s e cond c u r v e w h i c h t h e y s u g g e s t e d i s t h e m u s c l e ' s c o n t r i b u t i o n t o h i p f l e x i o n . The d i f f e r e n t m u s c l e a c t i v a t i o n p a t t e r n o f r e c t u s f e m o r i s - h a v i n g two b u r s t s o f a c t i v i t y d u r i n g t h e g a i t c y c l e , w h i l e t h e v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s have o n l y one - i s because i t i s a t w o - j o i n t m u s c l e . Schwab e t a l . (1983) have r e p o r t e d t h a t s u r f a c e e l e c t r o d e s a r e n o t s e n s i t i v e enough t o d e p i c t t h e EMG p a t t e r n o f s p e c i f i c m u s c l e s b u t r a t h e r a r e r e p r e s e n t a t i v e o f t h e a c t i v i t y o f a mus c l e g r o u p . However , t h e EMG p r o f i l e s f r om t h i s s t u d y i n d i c a t e t h a t t h e r e was a d i f f e r e n c e i n t h e a c t i v i t y p a t t e r n o f r e c t u s f e m o r i s d u r i n g r u n n i n g g a i t compared t o t h e v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s . F u r t h e r m o r e , t h e r e 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 peak EMG a m p l i t u d e s o f - 23 -r e c t u s f e m o r i s and t h e v a s t u s l a t e r a l i s (p = 0 . 008 ) and r e c t u s f e m o r i s and t h e v a s t u s m e d i a l i s (p = 0 . 007 ) d u r i n g s t a n c e phase ( T a b l e I I ) . In summary, a c o m p a r i s o n o f t h e a v e r age EMG p a t t e r n s o f t h e e x p e r i -men ta l g roup t o t h e c o n t r o l g roup r e v e a l e d t h e p h a s i n g o f t h e p a t t e r n s t o be s i m i l a r . D i f f e r e n c e s i n t h e a m p l i t u d e o f t h e c u r v e s o f t h e two g r oups were f o u n d ; i n p a r t i c u l a r t h e a m p l i t u d e s o f t h e m u s c l e a c t i v i t y p a t t e r n s o f t h e e x p e r i m e n t a l g roup were o b s e r v e d t o be l e s s t h an t h a t o f t h e c o n t r o l g r o u p . However , t h e s e d i f f e r e n c e s were n o t f o u n d t o be s t a t i s t i c a l l y s i g n i f i c a n t . T h i s l a c k o f a s t a t i s t i c a l d i f f e r e n c e may have r e s u l t e d f o r d i f f e r e n t r e a s o n s . I t may be t h a t t h e d i f f e r e n c e s i n t h e mus c l e a c t i v a t i o n p a t t e r n s between a ' n o r m a l ' g roup o f r u n n e r s and a g roup o f r u n n e r s w i t h PFPS a r e t o o s u b t l e f o r t h e EMG t o r e c o r d even though t h e l i t e r a t u r e has s u g g e s t e d t h a t t h e r e may be q u a d r i c e p s weakness a s s o c i a t e d w i t h P FPS , and more s p e c i f i c a l l y weakness o f v a s t u s m e d i a l i s (LeVeau & R o g e r s , 1980; F o x , 1 9 7 5 ) . R i c h a r d s e t a l . (1985) have s u g g e s t e d t h a t t h e a l t e r e d g a i t o f a s e v e r e l y d i s a b l e d p e r s o n w i l l r e s u l t i n changes i n t h e t i m i n g o f t h e EMG p a t t e r n s , however , t h e g a i t o f p a t i e n t s w i t h PFPS i s n o t u s u a l l y s e v e r e l y a f f e c t e d by t h e i r c o n d i t i o n , and i n t h e c a s e o f t h e s u b j e c t s i n t h i s s t u d y many were s t i l l r u n n i n g . I t may a l s o be t h a t a v e r a g i n g t h e EMG p a t t e r n s o f i n d i v i d u a l s w i t h a c l i n i c a l c o n d i t i o n o n l y a v e r a g e s t h e d i f f e r e n c e s o f each o f t h o s e s u b j e c t s . C l i n i c a l l y i t wou l d be more b e n e f i c i a l t o a n a l y z e each i n d i v i d u a l ' s r e s u l t s compared t o a ' n o rm ' t o d e t e r m i n e how o r i f t h e p a t i e n t d i f f e r s , and t h e n t r e a t m e n t c o u l d be d i r e c t e d t o c o r r e c t i n g t h e p r o b l e m . - 24 -Peak Concentric and Eccentric Torque Values of the Knee Extensor and F1exor Muscles The r e s u l t s show t h a t t h e r e was no s t a t i s t i c a l l y 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 s u b j e c t s w i t h PFPS and t h e g roup o f s u b j e c t s f r e e o f knee p a i n and w i t h normal a l i g n m e n t when t h e mean peak c o n c e n t r i c and e c c e n t r i c t o r q u e v a l u e s were compared , f o r b o t h t h e r i g h t q u a d r i c e p s and h a m s t r i n g s . To d a t e t h e r e have been few s t u d i e s o f t h e q u a d r i c e p s and h a m s t r i n g s t o r q u e s a t c e r t a i n v e l o c i t i e s i n young women, and o f t h e s e few t h e y have o n l y i n v e s t i g a t e d c o n c e n t r i c m u s c l e a c t i v i t y . Wya t t & Edwards (1981) s t u d i e d 50 n o n - a t h l e t i c f e m a l e s u b j e c t s aged 25 - 34 y e a r s , a t t h r e e a n g u l a r v e l o c i t i e s . They f ound a t 180\u00C2\u00B0/s t h a t t h e g r o u p ' s mean peak t o r q u e s were 57 f t - l b s . (77 N.m) f o r t h e q u a d r i c e p s and 45 f t - l b (61 N.m) f o r t h e h a m s t r i n g s . D i b r e z z o e t a l . (1985) s t u d i e d 241 n o n - a t h l e t i c f e m a l e s aged 18 - 28 y e a r s b u t o n l y a t 60\u00C2\u00B0/s . B e r g e t a l . (1985) s t u d i e d 13 f e m a l e c o l l e g e b a s k e t b a l l p l a y e r s and f ound t h e i r mean peak t o r q u e s t o be 78 .7 f t - l b ( 107 N.m) f o r t h e r i g h t knee e x t e n s o r s and 5 6 . 3 f t - l b ( 76 N.m) f o r t h e r i g h t knee f l e x o r s a t 180\u00C2\u00B0/s. R i c h a r d s (1981) s t u d i e d 19 f e m a l e s whose ages r anged f r om 21 - 60 y e a r s whose a c t i v i t y l e v e l s were no t s t a t e d , and she r e p o r t e d t h e i r mean peak t o r q u e f o r t h e q u a d r i c e p s t o be 8 0 . 9 N.m and f o r t h e h a m s t r i n g s t o be 4 8 . 1 N.m, a t 180\u00C2\u00B0/s. A l l o f t h e s e s t u d i e s used t h e Cybex I I i s o k i n e t i c dynamometer , and i n each c a s e t h e s u b j e c t s were t e s t e d i n s i t t i n g w i t h a back s u p p o r t . Each g roup o f i n v e s t i g a t o r s a l s o p r e s e n t e d t h e i r r e s u l t s as a h a m s t r i n g s / q u a d r i c e p s r a t i o (H/Q r a t i o ) - t h a t i s t h e peak t o r q u e o f - 25 -c o n c e n t r i c knee f l e x i o n d i v i d e d by t h e peak t o r q u e o f c o n c e n t r i c knee e x t e n s i o n . In t h i s c a s e a t an a n g u l a r v e l o c i t y o f 180\u00C2\u00B0/s Wya t t & Edwards r e p o r t e d a r a t i o o f . 7 9 , B e r g e t a l . r e p o r t e d .72 and R i c h a r d s f o und a r a t i o o f . 6 0 . The d i f f e r e n c e i n t h e r a t i o ' s may be due t o t h e d i f f e r e n t a c t i v i t y l e v e l s and t h e d i f f e r e n t age g roups o f t h e s u b j e c t s i n each s t u d y . The t e s t i n g f o r t h i s s t u d y was p e r f o r m e d on a KINCOM a t an a n g u l a r v e l o c i t y o f 200\u00C2\u00B0/s w i t h t h e s u b j e c t s s e a t e d and s u p p o r t e d by a b a c k r e s t . The g r a v i t y c o r r e c t i o n o p t i o n was n o t used so t h a t c o m p a r i s o n s c o u l d be made t o o t h e r s t u d i e s . Those f e m a l e s who were r u n n i n g a minimum o f 16 km week (10 m i l e s / w e e k ) and who were f r e e o f l o w e r e x t r e m i t y a b n o r m a l i t i e s and p a i n had a c o n c e n t r i c mean peak t o r q u e o f 112 .6 N.m f o r t h e r i g h t q u a d r i c e p s and 9 8 . 5 N.m f o r t h e r i g h t h a m s t r i n g s . The mean H/Q r a t i o o f t h i s g roup was . 8 8 . Nosse (1982) r e v i e w e d 50 r e p o r t s o f h a m s t r i n g s / q u a d r i c e p s r a t i o s and f ound t h a t t h e r a t i o s v a r i e d f r om .43 - . 9 0 , unde r a v a r i e t y o f c o n d i t i o n s . He s u g g e s t e d t h a t i t i s n e c e s s a r y t o c o n s i d e r t h e a n g u l a r v e l o c i t y o f t h e t e s t , t h e t e s t i n g p o s i t i o n , t h e equ i pmen t u sed and t h e p o p u l a t i o n b e i n g i n v e s t i g a t e d b e f o r e c ompa r i n g o r g e n e r a l i z i n g f r om one s t u d y t o a n o t h e r . Appen & Duncan (1986) e l a b o r a t e f u r t h e r on s u b j e c t c h a r a c t e r i s t i c s , s u g g e s t i n g t h a t s e x , age , a c t i v i t y l e v e l and t y p e o f a c t i v i t y a l s o i n f l u e n c e t h e t o r q u e v a l u e s . They have f o u n d i n t h e i r r e s e a r c h t h a t a t h i g h c o n c e n t r i c v e l o c i t i e s (300\u00C2\u00B0/s) , t h e r e was a s i g n i f i c a n t d i f f e r e n c e between t y p e s o f c o m p e t i t o r s , w h i c h may i n d i c a t e t h a t f i b r e t y p e c o m p o s i t i o n o r f i b r e s i z e i s a f a c t o r i n peak t o r q u e - 26 -v a l u e s . F u r t h e r m o r e , t h e y n o t e d t h a t g r a v i t y a f f e c t s t h e measured t o r q u e s . A t each o f f o u r a n g u l a r v e l o c i t i e s (60\u00C2\u00B0/s, 180\u00C2\u00B0/s, 240\u00C2\u00B0/s and 300\u00C2\u00B0/s) t h e g r a v i t y c o r r e c t e d peak e x t e n s o r t o r q u e s were i n c r e a s e d compared t o t h e n o n g r a v i t y c o r r e c t e d t o r q u e s , w h i l e t h e g r a v i t y c o r r e c t e d f l e x o r peak t o r q u e s d e c r e a s e d . These d i f f e r e n c e s r e s u l t e d i n a 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 H/Q r a t i o s c o r r e c t e d and n o t c o r r e c t e d f o r g r a v i t y , w i t h t h e g r a v i t y c o r r e c t e d t o r q u e s l o w e r . As more s t u d i e s a r e p u b l i s h e d i t becomes a p p a r e n t t h a t t h e r e i s a need f o r b a s e l i n e o r normal d a t a f r om w e l l d e l i n e a t e d p o p u l a t i o n s w i t h w e l l d e f i n e d t e s t i n g p r o t o c o l s , so t h a t c o m p a r i s o n s can be made. Compar ing t h e r e s u l t s o f t h i s s t u d y ' s g roup o f f e m a l e r u n n e r s ( w i t h o u t PFPS) t o t h e non-a t h l e t i c f e m a l e s i n Wya t t & E d w a r d ' s s t u d y , t h e peak t o r q u e v a l u e s f o r t h e r u n n e r s were h i g h e r f o r b o t h t h e q u a d r i c e p s and h a m s t r i n g s , as wou l d be e x p e c t e d c o m p a r i n g a c t i v e and n o n - a c t i v e p o p u l a t i o n s . , In B e r g & c o w o r k e r s ' s t u dy t h e f e m a l e b a s k e t b a l l p l a y e r s had a mean H/Q r a t i o l e s s t h an t h e r e c r e a t i o n a l r u n n e r s f r om t h i s s t u d y , w h i c h was d e m o n s t r a t e d by t h e f a c t t h a t t h e mean peak e x t e n s o r t o r q u e s were n e a r l y t h e same (107 N.m compared t o 112 .6 N.m r e s p e c t i v e l y ) b u t t h e mean peak f l e x o r t o r q u e s had a g r e a t e r s p r e a d between them. The mean peak f l e x o r t o r q u e o f t h e b a s k e t b a l l p l a y e r s was l e s s t h a n t h a t o f t h e r u n n e r s (76 N.m compared t o 9 8 . 5 N .m) . T h i s c o m p a r i s o n i s i n d i c a t i v e o f d i f f e r e n c e s i n t y p e s o f a c t i v i t y and a c t i v i t y l e v e l s . However , one can n o t r u l e o u t t h a t t y p e s o f equ i pmen t ( i . e . , - Cybex v s K incom) may a l s o be c o n t r i b u t i n g t o t h e d i f f e r e n c e s . - 27 -A n o t h e r pu r po se o f e s t a b l i s h i n g n o r m a t i v e d a t a i s so t h a t c o m p a r i s o n s can be made t o c l i n i c a l f i n d i n g s . Campbe l l and G l e n n (1982) s t u d i e d t h e r e s u l t s o f r e h a b i l i t a t i o n i n ma le and f e m a l e p a t i e n t s w i t h c h o n d r o m a l a c i a , and o t h e r knee p r o b l e m s , and r e p o r t e d t h e mean peak t o r q u e s o f t h e knee m u s c l e s o f t h e i n v o l v e d l e g b e f o r e t r e a t m e n t t o be l e s s t h a n t h e same m u s c l e s o f t h e n o n - i n v o l v e d l i m b . R i c h a r d s e t a l . (1985) compared t h e mean peak knee e x t e n s o r and f l e x o r t o r q u e s o f r h e u m a t o i d a r t h r i t i c p a t i e n t s ( f u n c t i o n a l c l a s s I I ) t o a ' n o r m a l ' g r o u p , and f ound s i g n i f i c a n t d i f f e r e n c e s between t h e two g r o u p s . The r e s u l t s o f t h i s s t u d y have shown t h e c o n c e n t r i c mean peak t o r q u e s o f t h e q u a d r i c e p s and h a m s t r i n g s i n t h o s e p a t i e n t s w i t h PFPS ( T a b l e IV) n o t t o be s i g n i f i c a n t l y d i f f e r e n t f r om t h e c o n t r o l g roup ( T a b l e V ) . The r e s u l t s o f t h e s e s t u d i e s i n d i c a t e t h a t t h e c au se o f p a i n and t h e a c t i v i t y l e v e l a l l o w e d by a d i s a b i l i t y o r d y s f u n c t i o n o f t h e m u s c u l o s k e l e t a l s y s t em a r e i m p o r t a n t c o n s i d e r a t i o n s i n a n a l y z i n g t e s t r e s u l t s . One wou l d e x p e c t p a t i e n t s w i t h t h e d i s a b l i n g d i s e a s e o f r h e u m a t o i d a r t h r i t i s t o have s i g n i f i c a n t l y l e s s mus c l e s t r e n g t h compared t o a c o n t r o l g r o u p , w h i l e t h o s e p a t i e n t s w i t h PFPS a r e s t i l l r e l a t i v e l y a c t i v e a l t h o u g h t h e y may n o t be r u n n i n g as a f o rm o f e x e r c i s e . T h i s b r i n g s f o r t h t h e need t o d e t e r m i n e what i s c l i n i c a l l y s i g n i f i c a n t f o r each c o n d i t i o n . G o s l i n and C h a r t e r i s (1979) b e l i e v e t h a t t h e H/Q r a t i o c o u l d be an i n d i c a t o r o f c l i n i c a l a b n o r m a l i t y a t t h e knee o r an i n d i c a t o r o f t h e p o t e n t i a l f o r i n j u r y . T h i s r a t i o i s s p e e d - s p e c i f i c , as t h e a n g u l a r v e l o c i t y i n c r e a s e s t h e d i f f e r e n c e s between t h e c o n c e n t r i c peak t o r q u e s o f t h e q u a d r i c e p s and h a m s t r i n g s d e c r e a s e s (Wya t t and Edwa rds , 1 9 8 1 ) . The - 28 -c o n c e n t r i c H/Q r a t i o f r om t h i s s t u d y o f .88 f o r t h e c o n t r o l g roup a t an a n g u l a r v e l o c i t y o f 200\u00C2\u00B0/s, s u g g e s t s t h a t t h e peak t o r q u e d i f f e r e n c e s between t h e two mus c l e g r oups i s n o t g r e a t . The c o n c e n t r i c H/Q r a t i o f r om t h o s e s u b j e c t s w i t h PFPS was 1.02 ( T a b l e V I ) w h i c h was no t s t a t i s t i c a l l y d i f f e r e n t f r om t h e c o n t r o l g roup b u t w h i c h i s o u t s i d e o f t h e range r e p o r t e d by Nosse ( 1 9 8 2 ) . T h i s H/Q r a t i o s u g g e s t s t h a t on t h e a v e r age t h e s u b j e c t s w i t h PFPS had s i m i l a r s t r e n g t h i n t h e h a m s t r i n g s as i n t h e q u a d r i c e p s . The o n l y e c c e n t r i c i n v e s t i g a t i o n o f i s o k i n e t i c m u s c l e a c t v i t y f o und i n t h e l i t e r a t u r e i s t h a t by Komi (1973) d u r i n g w h i c h he s t u d i e d t h e e l bow f l e x o r s . He f ound t h a t as v e l o c i t y o f c o n t r a c t i o n i n c r e a s e d , t h e c o n c e n t r i c f o r c e d e c r e a s e d and t h e e c c e n t r i c f o r c e i n c r e a s e d . From t h e r e s u l t s o f t h i s s t u d y , a t 200\u00C2\u00B0/s, t h e e c c e n t r i c mean peak t o r q u e s f o r b o t h t h e c o n t r o l g roup and t h e e x p e r i m e n t a l g roup were h i g h e r t h a n t h e c o n c e n t r i c mean peak t o r q u e s f o r t h e same m u s c l e s ( T a b l e I V ) . The r e s u l t s s u g g e s t t h a t f u r t h e r s t u d y i s n e c e s s a r y t o d e t e r m i n e i f a s i m i l a r f o r c e -v e l o c i t y r e l a t i o n s h i p e x i s t s i n c l i n i c a l c o n d i t i o n s ( s u c h as PFPS) as w e l l as i n t h e m u s c l e s o f normal h e a l t h y s u b j e c t s . A l t h o u g h t h e r e a r e no o t h e r s t u d i e s w h i c h have r e p o r t e d e c c e n t r i c peak t o r q u e s o f t h e q u a d r i c e p s and h a m s t r i n g s w i t h w h i c h t o compare , i t i s v a l u a b l e t o no t e t h e f i n d i n g s f r om t h i s s t u d y f o r t h e c o n t r o l g roup and t h e e x p e r i m e n t a l g r oup ( T a b l e IV) so t h a t f u t u r e c o m p a r i s o n s c an be made. S i m i l a r l y t h e r e has been no l i t e r a t u r e on t h e e c c e n t r i c H/Q r a t i o . The re was n o t a s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e between t h e two g roups when c ompa r i n g e c c e n t r i c H/Q r a t i o s i n t h i s s t u d y , however , as - 29 -p r e v i o u s l y s t a t e d i t i s u s e f u l t o n o t e t h e r a t i o s ( T a b l e V I ) f o r f u t u r e c o m p a r i s o n s . I t i s i n t e r e s t i n g t o no t e f r om t h e r e s u l t s t h a t t h e c o n c e n t r i c and e c c e n t r i c mean peak t o r q u e v a l u e s o f t h e h a m s t r i n g s f o r b o t h s u b j e c t g roups a r e c l o s e r t o g e t h e r w h i l e t h e mean peak t o r q u e s o f each g roup f o r t h e q u a d r i c e p s a r e much f a r t h e r a p a r t ( T a b l e I V ) . In summary, t h e r e s u l t s o f o u r i s o k i n e t i c t e s t i n g have r e v e a l e d t h a t -i ) t h e mean c o n c e n t r i c H/Q r a t i o ( 1 . 0 2 ) o f t h o s e s u b j e c t s w i t h PFPS was above t h e r ange t h a t has been r e p o r t e d i n t h e l i t e r a t u r e . T h i s a b n o r m a l l y h i g h r a t i o s u g g e s t e d t h a t t h e mean peak t o r q u e o f t h e h a m s t r i n g s was n e a r l y t h e same as t h e mean peak t o r q u e o f t h e q u a d r i c e p s . i i ) a t an a n g u l a r v e l o c i t y o f 200\u00C2\u00B0/s t h e c o n c e n t r i c and e c c e n t r i c H/Q r a t i o s were d i f f e r e n t , due t o t h e f a c t t h a t t h e c o n c e n t r i c and e c c e n t r i c mean peak t o r q u e s o f t h e h a m s t r i n g s were c l o s e r t o g e t h e r w h i l e t h e c o n c e n t r i c and e c c e n t r i c mean peak t o r q u e s o f t h e q u a d r i c e p s had a g r e a t e r s p r e a d between them. - 30 -i i i ) when c o n s i d e r i n g c l i n i c a l f i n d i n g s compared t o no rms , i t a ppea r s t h a t c l i n i c a l s i g n i f i c a n c e d i f f e r s f r om s t a t i s t i c a l s i g n i f i c a n c e , and t h a t each c o n d i t i o n may have a d i f f e r e n t l e v e l o f s i g n i f i -c an ce d epend i ng upon p a i n , m u s c u l o s k e l e t a l i n v o l v e m e n t and deg ree o f d i s a b i l i t y . - 31 -CONCLUSIONS The r e s u l t s o f t h i s s t u dy have shown t h a t : 1. From a v i s u a l a n a l y s i s o f t h e mean EMG p r o f i l e s o f t h e e x p e r i m e n t a l g roup s upe r imposed on t h e c o n t r o l g r o u p ' s mean EMG p a t t e r n + one s t a n d a r d d e v i a t i o n , t h e mean mus c l e a c t i v i t y o f t h e v a s t u s m e d i a l i s , r e c t u s f e m o r i s and t h e v a s t u s l a t e r a l i s was s i m i l a r ( w i t h i n +^ one s t a n d a r d d e v i a t i o n ) f o r s u b j e c t s w i t h p a t e l l o f e m o r a l p a i n syndrome compared t o s u b j e c t s f r e e o f knee p a i n and w i t h normal l o w e r e x t r e m i t y a l i g n m e n t , d u r i n g t r e a d m i l l r u n n i n g . A d d i t i o n a l l y , a m u l t i v a r i a t e a n a l y s i s (MANOVA), o f t h e peak EMG a m p l i t u d e s r e v e a l e d t h a t t h e r e was n o t a s i g n i f i c a n t d i f f e r e n c e between t h e two g r o u p s . 2 . The mean EMG p a t t e r n f o r r e c t u s f e m o r i s f r om bo t h g roups was d i f f e r e n t f r om t h e v a s t u s m e d i a l i s and t h e v a s t u s l a t e r a l i s , i n t h a t r e c t u s f e m o r i s had a b u r s t o f a c t i v i t y d u r i n g s t a n c e phase and a second b u r s t o f a c t i v i t y d u r i n g s w i n g , w h i l e t h e v a s t u s med i a l i s and t h e v a s t u s l a t e r a l i s had o n l y one b u r s t o f a c t i v i t y d u r i n g s t a n c e p h a s e . F u r t h e r m o r e , t h e r e 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 i n t h e peak EMG a m p l i t u d e s o f r e c t u s f e m o r i s compared t o t h e v a s t u s m e d i a l i s and r e c t u s f e m o r i s compared t o t h e v a s t u s l a t e r a l i s d u r i n g s t a n c e p h a s e . 3 . The r e was no s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e between t h e s u b j e c t s w i t h and w i t h o u t p a t e l l o f e m o r a l p a i n syndrome when t h e i r - 32 -mean peak c o n c e n t r i c and e c c e n t r i c t o r q u e v a l u e s were compared f o r t h e r i g h t h a m s t r i n g s and q u a d r i c e p s . S i m i l a r l y a t - t e s t o f t h e peak t o r q u e v a l u e s e x p r e s s e d as a h a m s t r i n g s / q u a d r i c e p s r a t i o showed t h a t t h e r e was no t a 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 g r o u p s . However , t h e mean c o n c e n t r i c H/Q r a t i o f r om t h e s u b j e c t s w i t h PFPS was 1.02 wh i c h i s o u t s i d e o f t h e normal r ange wh i c h has been r e p o r t e d i n t h e l i t e r a t u r e . - 3 3 -RECOMMENDATIONS Based on t h e u n d e r s t a n d i n g g a i n e d as a r e s u l t o f t h i s s t u d y , t h e f o l l o w i n g recommenda t i ons a r e s u g g e s t e d f o r f u t u r e i n v e s t i g a t i o n s . 1. The s i z e o f t h e c o n t r o l g roup must be g r e a t e r so t h a t t h e mean EMG p r o f i l e + one s t a n d a r d d e v i a t i o n f r om each mus c l e wou l d have l e s s v a r i a b i l i t y and b e t t e r r e p r e s e n t a normal d i s t r i b u t i o n . 2. A c t i v i t i e s su ch a s a s c e n d i n g o r d e s c e n d i n g s t a i r s o r s q u a t t i n g may r e v e a l g r e a t e r d i f f e r e n c e s i n t h e EMG p r o f i l e s o f t h o s e s u b j e c t s w i t h p a t e l l o f e m o r a l p a i n syndrome compared t o a c o n t r o l g r o u p , as t h e j o i n t r e a c t i o n f o r c e s t h r o u g h t h e p a t e l l o f e m o r a l j o i n t a r e known t o be h i g h d u r i n g t h o s e a c t i v i t i e s and p a t i e n t s o f t e n c o m p l a i n o f p a i n d u r i n g t h o s e a c t i v i t i e s . 3 . By r e c o r d i n g t h e EMG a c t i v i t y o f t h e m u s c l e s s i m u l t a n e o u s l y w i t h t h e mus c l e t e s t i n g and t h en r e c o r d i n g t h e m u s c l e a c t i v i t y d u r i n g a f u n c t i o n a l a c t i v i t y w i t h o u t r emov ing t h e e l e c t r o d e s , t h e i n v e s t i g a t o r wou l d be a b l e t o d e t e r m i n e t h e p e r c e n t a g e o f mus c l e a c t i v i t y d u r i n g a c t i v i t y compared t o a max imal s t r e n g t h t e s t . 4. F u r t h e r s t u d y may i n v o l v e p r e - t r e a t m e n t and p o s t - t r e a t m e n t EMG and mus c l e s t r e n g t h e v a l u a t i o n o f p a t i e n t s w i t h p a t e l l o f e m o r a l p a i n syndrome. - 34 -REFERENCES A n d e r s o n , J . E . , e d . G r a n t ' s A t l a s o f Ana tomy. V I I I E d i t i o n . W i l l i a m s and W i l k i n s C o . , B a l t i m o r e . 1983 . Appen , E . L . , Duncan , P.W. 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Q u a n t i t a t i v e r e l a t i o n s h i p between s u r f a c e EMG and i n t r a m u s c u l a r e l e c t r o m y o g r a p h i c a c i t i v t y i n v o l u n t a r y movement. Ame r i c an J o u r n a l o f P h y s i c a l M e d i c i n e . 5 1 : 2 8 5 - 2 9 5 . 1972 . C a i l l i e t , R. Knee P a i n and D i s a b i l i t y . F . A . D a v i s & C o . , P h i l a d e l p h i a . 1974 . C a m p b e l l , D . E . , G l e n n , W. R e h a b i l i t a t i o n o f knee f l e x o r and knee e x t e n s o r mus c l e s t r e n g t h i n p a t i e n t s w i t h m e n i s e c t o m i e s , l i g a m e n t o u s r e p a i r s , and c h o n d r o m a l a c i a . P h y s i c a l T h e r a p y . 6 2 : 1 0 - 1 5 . 1982 . C l e m e n t , D . B . , T a u n t o n , J . E . , S m a r t , G.W., M c N i c o l , K . L . A s u r v e y o f o v e r u s e r u n n i n g i n j u r i e s . The P h y s i c i a n and S p o r t s M e d i c i n e . 9 : 4 7 - 5 8 . 1 9 8 1 . D e l a g i , E . 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APPENDIX 1 TABLE VIII C l i n i c a l C h a r a c t e r i s t i c s o f t h e C o n t r o l Group S u b j e c t s CS CR GG J F LS MR PB PW SL SO SP VA Age (years) He ight (cm) Weight (kg) Km/wk runn ing 20 155 60.9 19 22 155 54.5 24 20 167.5 58.1 56 21 160 54.5 16 27 165 60 56 32 170 53.6 24 25 172.5 56.4 32 21 160 53.2 24 29 165 63.6 40 23 175 63.6 40 25 170 54 19 26 167.5 53.2 48 Knee pa in no no no no no no no no no no no no Knee a l ignment va lgus va lgus va lgus varus varus varus varus varus varus va lgus varus va lgus Q-angle 12\u00C2\u00B0 12\u00C2\u00B0 10\u00C2\u00B0 12\u00C2\u00B0 12\u00C2\u00B0 15\u00C2\u00B0 15\u00C2\u00B0 14\u00C2\u00B0 12\u00C2\u00B0 13\u00C2\u00B0 12\u00C2\u00B0 10\u00C2\u00B0 Rear foot varus a l ignment < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 3\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4 \u00C2\u00B0 Fo re foo t varus a l i gnment < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 3\u00C2\u00B0 <4\u00C2\u00B0 < 4\u00C2\u00B0 < 4\u00C2\u00B0 < 2\u00C2\u00B0 < 3\u00C2\u00B0 < 3\u00C2\u00B0 < 4 0 Overpronat ion no m i l d no m i l d m i l d no no m i l d no no no no Leg-1ength equal equal equal R 0.4 J e ^ 0 . 3 . \u00E2\u0080\u00A2 0.2 \u00E2\u0080\u00A2 0 . 1 J ^\u00E2\u0080\u00A2 in i i-iMMiiHU . j \\\&WA 10 20 30 40 50 60 % C Y C L E 70 80 90 100 SUBJECT CS. FIGURE 6 3 0 4 0 5 0 6 0 % C Y C L E 7 0 8 0 9 0 1 0 0 SUBJECT GG FIGURE 7 a . 6 r\ 0 . 5 _ > 0 . 4 _ ^ 0 . 3 _ % C Y C L E SUBJECT JF FIGURE 8 0 . 6 r\ 0 . 5 _ > 0 . 4 _ \u00C2\u00A3 3 _ 2 _ > 0 1 _ 0 0 _ 0 6 _ ^ 0 . 5 _ > 0 . 4 _ ^ 0 . 3 _ 2 _ C 0 - 1 0 0 0 6 _ 0 5 _ > 0 4 _ \u00C2\u00A3 0 3 _ 0 2 _ 0 . 1 _ > 0 . 0 0 5 0 6 0 % C Y C L E 7 0 T 8 0 T 9 0 4^ in 1 0 0 SUBJECT LS FIGURE 9 T 4 0 5 0 6 0 % C Y C L E 1 0 0 SUBJECT MR FIGURE 10 r\ 0 . 5 _ > 0 . 4 _ ^ 0 . 3 _ \u00E2\u0080\u00A2 0 . 2 a. 0 . 1 J 0 . 0 0 1 0 2 0 3 0 4 0 5 0 6 0 % C Y C L E \"1 1 \" \u00E2\u0080\u00A2 \" I I 7 0 8 0 9 0 1 0 0 SUBJECT PB FIGURE 11 0.0 0.6 ^ 0.5 _ > 0 . 4 _ \u00C2\u00A3 ^ 0 . 3 \u00E2\u0080\u00A2 0 . 2 J 0 . 1 J ^ 0.5 J > 0. 4 ^ 0.3 _ ^ \u00E2\u0080\u00A2 0 . 2 . > 0 . 1 J 0.0 0 ! ! 1 ^ * H J * * * ^ t i K j i i i i i i i i i | i i \u00C2\u00AB i j . i - M : i . : | i m r H\u00C2\u00AB*p 40 50 % CYCLE l i i l ; i i i | i i n i i i i i | i i 60 70 80 90 100 SUBJECT PW FIGURE 12 SUB.JECT SL FIGURE 13 0.6 r\ 0 . 5 _ > 0 . 4 _ E ^ 0 .3 _ ^ 0 . 5 _ > 0 . 4 _ % CYCLE SUBJECT SO FIGURE 14 0.6 ^ 0.5 J > 0 . 4 _ ^ 0 .3 _ ^ 0.5 _ > 0 . 4 _ ^ 0 .3 _ rx 0.5 _ > 0 . 4 _ ^ 0.3 _ 10 20 30 40 50 60 70 80 90 100 % CYCLE SUBJECT SP FIGURE 15 0*6 . ' 1 1 1 n 1 1 ' ~ ~ T 1 1 % C Y C L E SUBJECT VA - 53 -APPENDIX 2 TABLE IX I n d i v i d u a l Peak To rque V a l u e s f o r t h e R i g h t Leg a t 200\u00C2\u00B0/s Q u a d r i c e p s H a m s t r i n g s SUBJECTS C o n t r o l Group C o n c e n t r i c E c c e n t r i c C o n c e n t r i c E c c e n t r i c CR 100 166 77 99 CS 98 197 104 132 GG 90 72 88 97 J F 137 172 139 154 LS 109 104 92 110 MR 122 198 103 125 PB 114 202 127 150 PW 90 169 74 92 SL 116 124 73 63 SO 129 193 115 135 SP 164 276 118 142 VA 82 168 72 96 imenta l Group SC 87 144 107 138 HB 128 84 111 120 EC 76 80 89 91 TR 78 110 66 66 RW 90 168 122 158 SS 114 233 96 121 JH 121 164 85 105 JG 67 132 73 92 - 54 -TABLE X I n d i v i d u a l C o n c e n t r i c and E c c e n t r i c H a m s t r i n g s / Q u a d r i c e p s R a t i o s F o r The R i g h t Leg SUBJECTS C o n t r o l Group C o n c e n t r i c E c c e n t r i c CR .77 .60 CS 1.06 .67 GG .98 1.35 J F 1.01 .90 LS .84 1.06 MR .84 .63 PB 1.11 .74 PW .82 .54 SL .63 .51 SO .89 .70 SP .72 .51 VA .88 .57 E x p e r i m e n t a l Group SC 1.23 .95 HB .87 1.43 EC 1.17 1.14 TR .85 .60 RW 1.36 .94 SS .84 .52 JH .70 .64 JG 1.09 .70 - 55 -APPENDIX 3 Individual Muscle Activation Patterns The c l i n i c a l e x a m i n a t i o n o f t h e e i g h t s u b j e c t s w i t h p a t e l l o f e m o r a l p a i n , p l u s t h e r e s u l t s o f t h e i r dynamic s t r e n g t h t e s t i n g i s summar i zed i n T a b l e X I . TABLE XI C l i n i c a l C h a r a c t e r i s t i c s and Dynamic S t r e n g t h o f t h o s e S u b j e c t s W i t h R i g h t P a t e l l o f e m o r a l P a i n Syndrome Age (years) He ight (cm) Weight (kg) Km/week runn ing Pa in - l o c a t i o n - du ra t i on - w i t h runni Knee a l ignment SC HB EC TR RW SS 23 24 22 15 35 20 165 167.5 160 155 167.5 160 56.8 63.6 53.6 54.5 59.1 61.4 24 19 40 8 19 24 JH JG 22 36 167.5 152.5 61.4 50 24 16 medial medial medial i n f r a - media l r e t r o - r e t r o - p a t e l l a r r e t r o -pa te ! 1 a r medial medial i n f r a p a t e l l a r l a t e r a l p a t e l l a r p a t e l l a r 6-7 y r s 5 y r s 3 mo 2 y r s 2-3 y r s 6 y r s ng yes yes yes yes yes yes va lgus va lgus va lgus r e c u r - varus varus vatum va lgus 2 y r s yes varus 6 mo yes va lgus Q-angle 15\u00C2\u00B0 20\u00C2\u00B0 20\u00C2\u00B0 18\u00C2\u00B0 20\u00C2\u00B0 17\u00C2\u00B0 20\u00C2\u00B0 19\u00C2\u00B0 Rear foot varus a l ignment 3\u00C2\u00B0 8\u00C2\u00B0 8\u00C2\u00B0 10\u00C2\u00B0 6\u00C2\u00B0 10\u00C2\u00B0 4\u00C2\u00B0 5\u00C2\u00B0 Fo r e f oo t varus a l ignment 10\u00C2\u00B0 6\u00C2\u00B0 10\u00C2\u00B0 6\u00C2\u00B0 4\u00C2\u00B0 2\u00C2\u00B0 4\u00C2\u00B0 4\u00C2\u00B0 Overpronat ion y e s yes yes yes yes y e s yes yes Leg- length equal equal L "Thesis/Dissertation"@en . "10.14288/1.0096930"@en . "eng"@en . "Physical Education"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "Quadriceps muscle activity in female runners with patellofemoral pain syndrome"@en . "Text"@en . "http://hdl.handle.net/2429/26353"@en .