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A comparison of torque characteristics produced by the knee flexors and extensors during continuous concentric… Perkins, Christopher David 1992

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A COMPARISON OF TORQUE CHARACTERISTICS PRODUCED BY THE KNEE FLEXORS AND EXTENSORS DURING CONTINUOUS CONCENTRIC AND ECCENTRIC LOADING IN POWER ATHLETES AND AEROBICALLY TRAINED RUNNERS by CHRISTOPHER  DAVID PERKINS  B.P.E., U n i v e r s i t y o f New Brunswick, F r e d e r i c t o n , Brunswick 198 9 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF PHYSICAL EDUCATION in THE FACULTY OF GRADUATE STUDIES (Department o f P h y s i c a l Education)  We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA September 1992 © Christopher  David P e r k i n s ,  1992  New  In  presenting  degree freely  this  at the  thesis  in  partial  fulfilment  University  of  British  Columbia,  available for  copying  of  department publication  this or of  reference  thesis by  this  for  his thesis  and study. scholarly  or for  her  of  Physical  The University of British Vancouver, Canada  DE-6 (2/88)  Education  Columbia  requirements  gain shall  that  agree  may  representatives.  financial  the  I agree  I further  purposes  permission.  Department  of  It not  be is  that  the  an  advanced  Library shall make  permission for  granted  by  understood be  for  allowed  the that  without  it  extensive  head  of  my  copying  or  my  written  ABSTRACT  I t was t h e purpose o f t h i s i n v e s t i g a t i o n t o e v a l u a t e continuous concentric extensors  and e c c e n t r i c i s o k i n e t i c l o a d i n g  (KE) and f l e x o r s  i n power a t h l e t e s  (PA),  (KF) at 90, 135, and 180 deg/sec-1  a e r o b i c a l l y t r a i n e d runners  a c o n t r o l group o f moderately a c t i v e i n d i v i d u a l s of s i x t y h e a l t h y s u b j e c t s  o f the knee  (ATR), and  (MA). A t o t a l  (N= 20/group), aged 18-35 years, were  a s s i g n e d t o one o f the t h r e e groups a f t e r p h y s i o l o g i c a l ment c o n s i s t i n g o f v e r t i c a l (VO2 max) was performed.  assess-  jump and maximal oxygen consumption  Gravity  corrected  c o n c e n t r i c and  e c c e n t r i c average i s o k i n e t i c torque was measured from 75-30° o f knee f l e x i o n and knee f l e x i o n - e x t e n s i o n  ratios  (KF-E r a t i o s )  were c a l c u l a t e d . A three-way ANOVA w i t h two repeated measures  (angular  v e l o c i t y and muscle group) was c a l c u l a t e d f o r each measured contraction  type  (concentric  and e c c e n t r i c ) .  ANOVA w i t h two repeated measures  A t h i r d three-way  (angular v e l o c i t y and c o n t r a c -  t i o n type) was computed f o r t h e a n a l y s i s o f KF-E r a t i o s . nificant hoc  f i n d i n g s were f u r t h e r analyzed u s i n g  comparisons.  produce c o n c e n t r i c VO2  max, v e r t i c a l  Sig-  Scheffé's post  F i n a l l y c o r r e l a t i o n s between t h e a b i l i t y t o and e c c e n t r i c torque f o r t h e KE and KF and jumping a b i l i t y ,  and s k e l e t a l muscle mass  (SMM) were examined u s i n g Person Product Moment C o r r e l a t i o n s . I t was found that the power group produced s i g n i f i c a n t l y greater  average c o n c e n t r i c  e i t h e r t h e endurance  and e c c e n t r i c i s o k i n e t i c torque than  (concentric  and e c c e n t r i c at p< 0.01) or  sedentary  ( c o n c e n t r i c at p<  groups f o r both the significantly  KE  differ  and  (p>  0.05 KF  and  w h i l e the  0.05).  For  torque produced both e c c e n t r i c a l l y was KF  significantly  g r e a t e r at p<  at each angular v e l o c i t y  r a t i o s were s i g n i f i c a n t l y produced c o n c e n t r i c a l l y angular  (p<  As  isokinetic by  the  KE the  well, eccentric  KF-E  0.001) than those  ratios  (p<  significantly 0.01)  t h r e e groups f o r a l l  C o n c e n t r i c KF-E  ratios  angular v e l o c i t i e s 0.02)  d i d not  significantly  f o r both the  endurance  differ  the  i n any  sedentary groups  significantly of the  t h e r e were s i g n i f i c a n t  knee extensors and  jumping a b i l i t y w h i l e VO2 with v e r t i c a l  jumping  nor  t h r e e groups  and  and  significantly  important when d e s i g n i n g  rehabilitation  eccen-  vertical correlated  individualized  programs f o r a t h l e t e s who  f o r a c t i v i t i e s which r e q u i r e d i f f e r e n t  muscular c o n t r a c t i o n .  of  c o r r e l a t i o n s between  knee f l e x o r s SMM  change  ability.  These f i n d i n g s are c o n d i t i o n i n g and  max  or  significantly.  a b i l i t y to generate torque both c o n c e n t r i c a l l y  t r i c a l l y by  and  increased with i n c r e a s i n g  d i d not  with i n c r e a s i n g angular v e l o c i t y Finally,  the  endurance and  while e c c e n t r i c r a t i o s  subjects.  greater concentric  than e i t h e r  sedentary groups of s u b j e c t s who  training  not  than t h a t produced by  examined.  greater  groups d i d  concentrically  f o r each of the  power groups had  e c c e n t r i c KF-E  the  a l l groups  and  0.001  l a s t two  0.01)  velocities.  The  (p<  e c c e n t r i c at p<  velocities  are of  CONTENTS  Page(s) ABSTRACT  i i- i i i  CONTENTS  iv- vi  LIST OF TABLES  v i i  LIST OF FIGURES  viii  ACKNOWLEDGEMENT  ix  CHAPTER 1  1 - 10  I  II  III  Introduction  1-4  A  2-4  Imbalance vs Asymmetry  Statement o f the problem  5 - 8  A  Definitions  5-6  B  Delimitations  C  Limitations  D  Assumptions  7  E  Hypotheses  8  6 6-7  S i g n i f i c a n c e o f the study  9 - 10  CHAPTER 2 I  11 - 28 Literature A  Review  Methods o f examining muscle and f u n c t i o n i  Isometric  strength 11 - 14  / isotonic  11 - 12  Page(s) ii  Isokinetic  12 - 14  B  A n a l y s i s o f the running  C  Torque p r o d u c t i o n  motion  and muscle  14 - 16  fibre  composition  16 - 19  D  Knee f l e x i o n - e x t e n s i o n assessment  19 - 21  E  F a u l t s with p r e v i o u s  22 - 28  i  research  E x c l u s i v e measurement o f concentric contractions  ii  iii iv  Hip angle and s u b j e c t p o s i t i o n i n g during t e s t i n g  23 - 24  Lack o f g r a v i t y c o r r e c t i o n  24 - 25  Time t o reach p r e - s e t  angular  velocity V  22 - 23  25 - 27  I n c l u s i o n o f f a t mass when torque c o r r e c t e d f o r body weight... 27 - 28  CHAPTER 3 I  II  29 -34 Procedures A  Methodology  B  T e s t i n g Procedures  Design and C h a r a c t e r i s t i c s o f the data  CHAPTER 4 I  29 - 32 29 29 - 32  33 - 34  35 - 88 Results  35 - 62  vi Page(s)  II  A  Physical Characteristics  35 - 37  B  Physiological Characteristics  38 - 39  C  Anthropometric C h a r a c t e r i s t i c s  40 - 41  D  C o r r e c t e d C o n c e n t r i c Torque  42 - 48  E  C o r r e c t e d E c c e n t r i c Torque  49 - 53  F  Knee F-E R a t i o s  54 - 60  G  Correlations  61 - 62  Discussion  63 - 88  A  Group D i f f e r e n c e s  64 - 67  B  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 . . .  67 - 74  C  Knee Extensor and F l e x o r  74 - 79  D  KF-E R a t i o s  80 - 84  E  S i g n i f i c a n c e o f KF-E Asymmetry  84 - 86  F  Goal o f R e h a b i l i t a t i o n  86 - 87  CHAPTER 5  I  II  III  REFERENCES  Torque  8 9 - 92  Summary  89-90  Conclusions  90 - 91  Recommendations  91 - 92  93-99  TABLES  Tables  Page  4.1  Physical  characteristics  4.2  Physiological  4.3  Anthropometric  4.4  Corrected concentric  4.5  Corrected eccentric  4.6  KF-E r a t i o s  4.7  Correlation  characteristics characteristics torque torque  36 38 40 45 51 57  Matrix  62  FIGURES  Figures  Page  4.1  Group p h y s i c a l c h a r a c t e r i s t i c s  37  4.2  Group p h y s i o l o g i c a l  39  4.3  Anthropometric c h a r a c t e r i s t i c s  41  4.4  C o r r e c t e d c o n c e n t r i c torque  46  4.5  Muscle Group X Angular v e l o c i t y  4.6  Muscle Group X A t h l e t i c Group i n t e r a c t i o n .  4.7  C o r r e c t e d e c c e n t r i c torque  52  4.8  Muscle Group X A t h l e t i c Group i n t e r a c t i o n . . . .  53  4.9  KF-E r a t i o s  58  4.10  C o n t r a c t i o n type X A t h l e t i c Group interaction  59  4.11  C o n t r a c t i o n type X Angular interaction  60  characteristics  interaction..  velocity  47  .. 48  AKNOWLEDGEMENT  The  author would l i k e t o thank t h e committee chairman:  Dr  J.E. Taunton and committee members Dr. D.B. Clement and Dr. E.C.  Rhodes f o r t h e i r support  the p h y s i o l o g i c a l  and guidance.  Assistance during  t e s t i n g was p r o v i d e d by Mr. Dusan  Benicky.  A thank you i s not enough when e x p r e s s i n g my g r a t i t u d e toward my parents years.  f o r t h e i r support  F i n a l l y this thesis  waited p a t i e n t l y  d u r i n g these past few  i s d e d i c a t e d t o my fiancée who has  d u r i n g t h e past t h r e e years while I have  attempted t o achieve a dream.  Chapter 1 INTRODUCTION  Past  i s o k i n e t i c assessment of the knee j o i n t has  been  performed to i n v e s t i g a t e s e v e r a l d i f f e r e n t areas of i n t e r e s t t o both the  f i e l d s of r e s e a r c h  and  r e h a b i l i t a t i o n which i n c l u d e :  m o n i t o r i n g p r o g r e s s f o l l o w i n g the r e p a i r or r e c o n s t r u c t i o n knee l i g a m e n t ( s ) ,  the examination o f hamstring and  of  quadricep  torque curves a f t e r e i t h e r knee j o i n t or t h i g h muscle i n j u r y , the r e l a t i o n s h i p between muscle s t r e n g t h and muscle composition, and l a s t area,  the  knee f l e x i o n - e x t e n s i o n r a t i o s .  focus  (KF-E) imbalance.  abnormal KF-E  r a t i o may  (Holmes & A l d e r i n k Heiser  It i s t h i s  of many s t u d i e s , which examines the  r e l a t i o n s h i p between hamstring muscle s t r a i n and extensor  fibre  1984,  knee f l e x o r -  Although i t i s b e l i e v e d t h a t  an  have some a s s o c i a t i o n w i t h such i n j u r y B a i l e y & B r e m i l l e r 1981,  et a l . 1984), d e f i n i t e p r o o f has  yet t o be  Burkett  1970,  established  (Nosse 1982). Muscle s t r a i n i n j u r i e s  (MSI)  have a h i g h r a t e of  incidence  i n those s p o r t s which r e q u i r e some degree o f s p r i n t i n g , jumping, and/or r a p i d a c c e l e r a t i o n Stanton & Purdam 1989). Arge  (Arge 1985,  Brubaker & James  (1985), found t h a t i n runners, 33%  the MSI  v a r i e t y ; a 50%  r a t e of i n c i d e n c e  Garrett  1983,  (1974) as r e p o r t e d  of a l l i n j u r i e s were of i n those a t h l e t e s  p a r t i c i p a t i n g i n s p r i n t events. One  by  i d e a which has been o f f e r e d t o e x p l a i n the  frequency of these i n j u r i e s i s muscle imbalance.  abnormal  The  term  muscle imbalance  (MI) r e f e r s t o an asymmetrical d i f f e r e n c e  which e x i s t s between e x t r e m i t i e s o r between the a g o n i s t and a n t a g o n i s t o f t h e same e x t r e m i t y which may i n c l u d e s t r e n g t h , power, power-endurance, or other v a l u e when examining the same subject  (Grace 1985).  This imbalance i s c u r r e n t l y measured by  e v a l u a t i n g average and/or peak i s o k i n e t i c torque o f a g o n i s t and a n t a g o n i s t , d i v i d i n g the two measures with the r e s u l t b e i n g the ratio.  T h i s balance,  or l a c k t h e r e o f , i s deemed as b e i n g  i p s i l a t e r a l or c o n t r a l a t e r a l al.  ( G i l l i a m et a l . 1979, H e i s e r e t  1984) .  IMBALANCE VS ASYMMETRY P r e v i o u s s t u d i e s have examined KF-E r a t i o s u s i n g many d i f f e r e n t t e s t i n g procedures  and groups o f s u b j e c t s .  aspect which has been common t o a l l ,  One  however, i s the use o f the  term MI.  To date, r e s e a r c h examining t h i s r e l a t i o n s h i p has  suggested  t h a t MI between the KF and KE i s "unhealthy",  s i b l y c o n t r i b u t i n g t o the occurrence 1970, 1984).  o f hamstring  pos-  MSI (Burkett  B u r k e t t 1976, Cooper & F a i r 1978, S t a f f o r d & Granna The use o f t h i s term i n such a manner i s i n c o r r e c t .  One should c o n s i d e r t h a t because t h e KE and KF a r e two separate and d i s t i n c t groups o f muscle w i t h d i f f e r e n t a c t i o n s , i n n e r v a t i o n s , and are composed o f d i f f e r e n t percentages muscle f i b r e s  o f Type II  (Garrett 1983, P o l g a r 1973), imbalances  e x i s t between these two groups of muscle.  should  C o n s i d e r i n g the  s t r u c t u r a l d i f f e r e n c e s between the KE and KF perhaps a more a p p r o p r i a t e term t o d e s c r i b e an "unhealthy"  differencei n  torque p r o d u c t i o n i s asymmetry. There are two and s t r u c t u r a l .  d i f f e r e n t types of asymmetry:  functional  S t r u c t u r a l asymmetry measures d i f f e r e n c e s  which can be a s s o c i a t e d w i t h p h y s i c a l c h a r a c t e r i s t i c s such d i f f e r e n c e s i n muscle s i z e ,  innervation(s), origin(s)  i n s e r t i o n ( s ) , and muscle f i b r e composition.  However, gross s t r u c t u r a l asymmetrical  and  Therefore,  t u r a l asymmetry between the KE and KF should be  as  struc-  expected.  d i f f e r e n c e s between  l e g s , such as s i g n i f i c a n t l y d i f f e r e n t t h i g h c i r c u m f e r e n c e s ,  can  be p a t h o l o g i c a l i n nature. The nature.  second  form of asymmetry i s t h a t of a f u n c t i o n a l  F u n c t i o n a l asymmetry examines the d i f f e r e n t aspects of  muscle f u n c t i o n measured i n a v a r i e t y of ways r e g a r d l e s s of s t r u c t u r a l s t a t u s which i n c l u d e the c o o r d i n a t i o n of muscular c o n t r a c t i o n , speed of movement/joint angular v e l o c i t y , strength.  and  F u n c t i o n a l asymmetry e i t h e r between the KE and  and/or between the l e f t  KF  and r i g h t l e g can be c o n s i d e r e d as p r e -  d i s p o s i n g one t o i n j u r y . P r e v i o u s s t u d i e s have i n d i c a t e d t h a t peak and  average  torque i s g r e a t e r f o r the quadriceps than which the  hamstrings  are capable of producing at a l l angular v e l o c i t i e s p r e s e n t l y available for testing 1991,  (Baltzopolous & B r o d i e 1989,  Sanderson et a l . 1984).  Thus, i f the KE are  l y s t r o n g e r than the i p s i l a t e r a l KF, two muscle groups may  result  significant-  any c o c o n t r a c t i o n of these  r e s u l t i n the knee f l e x o r s b e i n g over-  powered by the f o r c e produced occurrence may  Ghena et a l .  by the knee e x t e n s o r s .  i n hamstring MSI  (Sutton 1984).  Such an  The l i t e r a t u r e addresses the measurement  of i s o k i n e t i c  knee f l e x i o n and e x t e n s i o n torque from many d i f f e r e n t tives.  In recent years t h e r e have been s e v e r a l advances i n the  c a p a b i l i t i e s o f i s o k i n e t i c dynamometers ized this entire  area o f r e s e a r c h .  which have  eccentric  characteristics  By i n v e s t i g a t i n g  revolution-  S t u d i e s were once  to i s o k i n e t i c c o n c e n t r i c e v a l u a t i o n o f muscle, now can a l s o be examined.  KF-E torque e c c e n t r i c a l l y ,  possible relationship  limited  isokinetic  we can  advance our knowledge concerning KF-E torques, t h e i r and  perspec-  to eccentric  hamstring MSI.  further  ratios,  STATEMENT OF THE PROBLEM  The purpose of t h i s study was  two-fold:  1) t o examine the  r e l a t i o n s h i p between c o n c e n t r i c and e c c e n t r i c torque as produced by the knee f l e x o r s and extensors and t h e i r KF-E  ratios  i n a manner which best s i m u l a t e d the l e n g t h - t e n s i o n r e l a t i o n s h i p s found d u r i n g running and 2) t o examine the d i f f e r e n c e s i n the a b i l i t y t o produce torque between power a t h l e t e s (PA), a e r o b i c a l l y t r a i n e d runners active individuals  (ATR), and a group of  moderately  (MA).  DEFINITIONS For the purpose of c l a r i f i c a t i o n ,  the f o l l o w i n g d e f i n i -  t i o n s are c o n s i d e r e d a p p l i c a b l e throughout  1) Torque —  the  study.  a t u r n i n g or r o t a r y f o r c e ; the product o f a f o r c e  and the p e r p e n d i c u l a r d i s t a n c e from the l i n e of a c t i o n o f the f o r c e to the a x i s of r o t a t i o n 2) Average Torque — a trial  the average recorded v a l u e measured d u r i n g  r e g a r d l e s s of i t s p o s i t i o n i n the range o f motion  3) Power Subject —  any s u b j e c t who  performs a v e r t i c a l  jump  of 65 cm or g r e a t e r and does not achieve a value of 60 ml/kg/min on the VO2 max  test  4) A e r o b i c a l l y T r a i n e d Subject —  any  s u b j e c t who  performs a  «  VO2  max  t e s t of g r e a t e r than or equal t o 60 ml/kg/min and  does not achieve a value of 65 cm on the v e r t i c a l test  jump  5) Moderately A c t i v e Subject a vertical  —  any s u b j e c t who cannot perform  jump of 65 cm nor can achieve a v a l u e  of 60  ml/kg/min on the VO2 max t e s t 6) C o n c e n t r i c  —  muscle c o n t r a c t i o n which occurs when the  i n v o l v e d muscle shortens w h i l e 7) E c c e n t r i c —  contracting  muscle c o n t r a c t i o n which occurs when t h e  i n v o l v e d muscle lengthens w h i l e  contracting  DELIMITATIONS The  r e s u l t s o f the study were d e l i m i t e d by:  1) Sample s i z e , 2) A b i l i t y  sex, age, l e v e l o f a t h l e t i c  status  of the t e s t e r t o ensure t h a t c o r r e c t procedures and  techniques were employed i n the measurement o f p h y s i o l o g i c a l t e s t s , anthropometry, and torque  evaluation  3) The s p e c i f i c angles i n the ROM which torque measurements were examined  LIMITATIONS The  r e s u l t s of t h i s study were l i m i t e d by:  1) E r r o r s o f data c o l l e c t i o n by t h e Beckman M e t a b o l i c ment C a r t . before  Measure-  T h i s was minimized by c a l i b r a t i n g t h e Beckman  each a e r o b i c endurance t e s t and by s t a n d a r d i z i n g the  t e s t i n g procedures and i n s t r u c t i o n s f o r a l l s u b j e c t s . 2) E r r o r s o f data c o l l e c t i o n by the Kin-Com i s o k i n e t i c dynamometer as w e l l as e r r o r s t h a t can occur i n the accuracy o f reading  values  o f f the r e c o r d i n g c h a r t .  These were m i n i -  mized by c a l i b r a t i n g t h e Kin-Corn b e f o r e each t e s t i n g s e s s i o n and through t h e s t a n d a r d i z a t i o n o f t e s t i n g  proced-  ures and i n s t r u c t i o n s , 3) A l t e r a t i o n i n s u b j e c t body p o s i t i o n d u r i n g t e s t i n g which was minimized through t h e use o f s t a b i l i z a t i o n s t r a p s . 4) The s u b j e c t r e p o r t i n g a c c u r a t e l y t h a t no p r e v i o u s extremity 5) A b i l i t y  lower  i n j u r y had o c c u r r e d .  o f t h e s u b j e c t s t o perform  c o r r e c t l y on t h e K i n -  Com. 6) Any r e f e r e n c e between running angular v e l o c i t i e s and those a v a i l a b l e f o r t e s t i n g on t h e Kin-Com remembering t h a t t h e speed o f running has been estimated t o occur at 800 deg/ sec"-^ and t h e maximal speed a v a i l a b l e f o r t e s t i n g on t h e Kin-Com i s 210 deg/sec"^.  ASSUMPTIONS The c o n s t r u c t o f t h i s study  included the f o l l o w i n g  assumptions : 1) That t h e r e s u l t s o f t h e i s o k i n e t i c torque  t e s t s were depend-  ant upon the e f f o r t and c o o p e r a t i o n o f each s u b j e c t 2) That t h e measurements recorded were only as a c c u r a t e as instrumentation  allowed  HYPOTHESES I t was h y p o t h e s i z e d t h a t : 1)  Torque produced 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  extensors w i l l be s i g n i f i c a n t l y by 2)  the knee f l e x o r s  g r e a t e r than t h a t produced  f o r a l l groups at a l l v e l o c i t i e s .  PA w i l l produce s i g n i f i c a n t l y g r e a t e r c o n c e n t r i c and eccent r i c torque f o r both the knee f l e x o r s either  3)  by the knee  and extensors than  the ATR or MA groups at a l l v e l o c i t i e s .  PA w i l l have s i g n i f i c a n t l y g r e a t e r c o n c e n t r i c and e c c e n t r i c KF-E  ratios  than the MA and ATR groups f o r each v e l o c i t y o f  contraction. 4a)  F o r a l l groups at each angular v e l o c i t y , ratios  w i l l be s i g n i f i c a n t l y  e c c e n t r i c KF-E  g r e a t e r than c o n c e n t r i c  ratios. 4b)  As angular v e l o c i t y  increases concentric r a t i o s  increase while e c c e n t r i c r a t i o s  will  will  remain unchanged f o r  a l l t h r e e groups. 5) V e r t i c a l  jumping a b i l i t y w i l l  significantly  torque p r o d u c t i o n while V02max and s k e l e t a l w i l l not s i g n i f i c a n t l y  correlate.  c o r r e l a t e with muscle mass  SIGNIFICANCE OF THE Hamstring  MSI  STUDY  are n o t o r i o u s f o r t h e i r slow r a t e o f h e a l i n g  and h i g h i n c i d e n c e of r e c u r r e n c e , thus they can be s e v e r e l y debilitating.  Knowledge of h e a l t h y a t h l e t e ' s KF-E  measured both 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 may a s s i s t a n c e t o s e v e r a l d i f f e r e n t people who ing  assist  ratios, be of i n the  train-  of a t h l e t e s . T h i s i n f o r m a t i o n c o u l d be used as a measuring  t o o l t o determine  i f t h e i r a t h l e t e s are capable of producing  and w i t h s t a n d i n g the f o r c e s p r e s e n t a s s o c i a t e d w i t h t h e i r particular  event.  As w e l l , t h i s knowledge may r e h a b i l i t a t i o n of a t h l e t e s who or  be u s e f u l d u r i n g the  have experienced hamstring  MSI  other i n j u r y such as damage t o knee ligament(s) where the  t h i g h musculature  plays a s i g n i f i c a n t role i n r e h a b i l i t a t i o n .  T h i s knowledge, c o l l e c t e d on i n d i v i d u a l s who o u s l y e x p e r i e n c e d hamstring  have not p r e v i -  i n j u r y , c o u l d be used as a guide-  l i n e which a i d s the p h y s i o t h e r a p i s t i n d e t e r m i n i n g i f the i n j u r e d a t h l e t e i s ready t o r e t u r n t o c o m p e t i t i o n without r i s k i n g further  injury.  R o t h s t e i n e t a l . (1987) have s t a t e d t h a t p r e v i o u s s t u d i e s performed  i n t h i s f i e l d have been f i l l e d w i t h e r r o r s which are  d i s c o v e r e d as more r e s e a r c h i s performed,  e v a l u a t i o n methods  are r e f i n e d and t e s t equipment i s improved.  Due  to previous  e r r o r s f u r t h e r i n v e s t i g a t i o n i n t h i s area u s i n g s t r i c t procedures  so  test  ' s p r i n t - l i k e ' torques can be measured remembering  the l i m i t a t i o n s o f the i s o k i n e t i c d e v i c e s such as the Kin-Com must be  performed.  Therefore, t h i s study was  designed t o f u r t h e r examine con-  c e n t r i c and e c c e n t r i c torques of the knee f l e x o r s and and KF-E  r a t i o s i n power a t h l e t e s ,  and moderately  Of f u r t h e r  interest to t h i s inves-  the r e l a t i o n s h i p between whole body s k e l e t a l  muscle mass, v e r t i c a l production.  runners,  a c t i v e i n d i v i d u a l s over t h r e e d i f f e r e n t v e l o c i -  t i e s of muscle c o n t r a c t i o n . t i g a t i o n was  aerobically trained  extensors  jumping a b i l i t y ,  and VO2 max  t o torque  Chapter 2 LITERATURE REVIEW  T h i s p a r t o f t h e paper i s d i v i d e d i n t o f i v e s e c t i o n s : p r e v i o u s methods o f examining muscle s t r e n g t h and f u n c t i o n , a n a l y s i s o f the running motion, torque p r o d u c t i o n and muscle f i b r e composition,  knee f l e x i o n - e x t e n s i o n assessment, and  f a u l t s with previous r e l a t e d research.  METHODS OF EXAMINING MUSCLE STRENGTH AND FUNCTION Past r e s e a r c h has i d e n t i f i e d two separate methods o f measuring muscle asymmetry:  i s o m e t r i c a l l y / i s o t o n i c a l l y and  isokinetically.  Isometrically / Isotonically Knee f l e x i o n and e x t e n s i o n scores as w e l l as KF-E r a t i o s were i n i t i a l l y performed i s o m e t r i c a l l y u s i n g a c a b l e t e n s i ometer b e f o r e i s o k i n e t i c dynamometers became popular, r e s u l t s measured i n 'pounds o f f o r c e ' .  As a r e s u l t ,  their force f o r  t h a t p a r t i c u l a r group o f muscles b e i n g examined c o u l d be measured at only one s p e c i f i c j o i n t angle.  Subjects would  e x e r t maximum e f f o r t at a f i x e d p o s i t i o n w i t h i n t h e range o f motion, and thus s t a t i c s t r e n g t h c o u l d be determined p a r t i c u l a r j o i n t angle  (Gleim 1978).  f o r that  Force measurements would  be taken at other j o i n t angles throughout  t h e range o f motion  (ROM) i n a s i m i l a r manner, but the s t r e n g t h o f t h e muscle group throughout  i t s ROM c o u l d only be p r o p e r l y c a l c u l a t e d by c o r r e l -  a t i n g t h e s t r e n g t h measurement t o the p r e c i s e j o i n t angle at which t h e measurement was taken The  (Sutton  1984) .  use o f i s o t o n i c t e s t i n g t o measure t h e s t r e n g t h o f a  muscle group has a l s o been employed i n t h e p a s t . of s t r e n g t h t e s t i n g r e q u i r e s t h e s u b j e c t t o l i f t  T h i s method a predeter-  mined weight, u s u a l l y a c e r t a i n percentage o f t h e i n d i v i d u a l ' s body weight.  The t e s t would continue  with  incremental  pro-  g r e s s i o n u n t i l t h e subject c o u l d no longer perform a complete ROM  (Anderson e t a l . 1991).  The primary l i m i t a t i o n o f t h i s  method o f t e s t i n g i s t h a t t h e maximum i s o t o n i c s t r e n g t h o f a muscle group i s o n l y as strong as t h e f o r c e t h a t i t can produce at t h e weakest p o i n t i n i t s ROM.  Both t h e i s o m e t r i c and i s o -  t o n i c methods o f e v a l u a t i n g muscle s t r e n g t h a r e s i m i l a r i n t h a t they measured f o r c e only at one s p e c i f i c j o i n t angle  (Sutton  1984).  Isokinetically With the development o f an e l e c t r o m e c h a n i c a l kept limb motion at a constant  device  which  predetermined v e l o c i t y , an  a l t e r n a t i v e method o f e v a l u a t i n g muscular s t r e n g t h was made a v a i l a b l e i n mid 1960's:  isokinetics.  Since  i t s conception,  i s o k i n e t i c measurement has proved t o be a s u p e r i o r a l t e r n a t i v e to p r e v i o u s 1969).  methods o f muscle assessment  (Moffroid et a l .  By a p p l y i n g accommodating r e s i s t a n c e t o match t h e  s t r e n g t h output o f a p a r t i c u l a r muscle group b e i n g t e s t e d , t h e i s o k i n e t i c system can o b j e c t i v e l y evaluate  and r e c o r d t h e  magnitude and p a t t e r n o f torque generated by a muscle group  across a s p e c i f i c j o i n t  (Gleim 1978).  In so doing,  i t also  allows an a c c u r a t e and complete d e t e r m i n a t i o n of muscle funct i o n between the i p s i l a t e r a l and c o n t r a l a t e r a l e x t r e m i t i e s and the a g o n i s t and a n t a g o n i s t muscle groups w i t h i n the same extremity  (Grace et a l . 1984).  A second b e n e f i t of i s o k i n e t i c  measurement i s t h a t i t allows the v e l o c i t y of c o n t r a c t i o n (angular v e l o c i t y of the j o i n t b e i n g measured) to be mined, thus e v a l u a t i n g muscle f u n c t i o n at d i f f e r e n t velocities The  predeterangular  (Sutton 1984).  e a r l y years of i s o k i n e t i c t e s t i n g made use o f the  CYBEX and then the CYBEX II i s o k i n e t i c dynamometers.  These  machines are capable of measuring peak torque and the angle at which i t occurs d u r i n g the ROM,  torque produced at  specific  angles, t o t a l work performed d u r i n g a c o n t r a c t i o n , the average power of a c o n t r a c t i o n , and torque a c c e l e r a t i o n energy.  All  measurements can be examined at angular v e l o c i t i e s ranging from 0 t o 300  deg/sec"^  (Burdett & VanSwearingen 1987).  Both,  however, are capable o f only e v a l u a t i n g i s o k i n e t i c muscular contractions  concentrically.  During the past decade t h e r e has been f u r t h e r advancement i n the a b i l i t y t o perform  f u n c t i o n a l muscle t e s t i n g .  Isokinetic  machines which are capable of e v a l u a t i n g a muscle e c c e n t r i c a l l y i n a d d i t i o n to c o n c e n t r i c examination k i n e t i c communicator  (Kin-Com), one  have been developed.  such instrument,  h y d r a u l i c a l l y driven, microcomputer-controlled  device  The  is a designed  t o measure torque and work 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 i s o k i n e t i c loading.  The  d e v i c e ' s c o n t r o l l e d modes o f e x e r c i s e  include i s o k i n e t i c ,  i s o t o n i c , and p a s s i v e j o i n t movement.  When  a s u b j e c t performs a movement on t h e Kin-Com, t h e dynamometer p r o v i d e s r e s i s t a n c e v i a a r o t a t i n g t r a n s d u c e r arm. and i t s o n - l i n e microsystem  The Kin-Com  computer are capable o f r e c o r d i n g  c o n c e n t r i c and e c c e n t r i c torque and work a t v e l o c i t i e s o f movement from 0 t o 210 deg/sec"-^  (Kin-Com, Med-Ex D i a g n o s t i c s  of Canada, Inc., 51 Leeder Ave.,  Coquitlam, B.C., V3K 3V5).  ANALYSIS OF THE RUNNING MOTION As mentioned  e a r l i e r , hamstring muscle s t r a i n has been  found t o be a common i n j u r y o c c u r r i n g t o s p r i n t e r s .  Before we  can a s s o c i a t e any cause o f such i n j u r y t o t h e frequency, we must f i r s t  d i s c u s s the running motion.  In r e v i e w i n g the r o l e o f t h e KF and KE i n the running motion,  t h e i r f u n c t i o n i s t o a l t e r n a t e l y a c t as both a prime  mover and a s t a b i l i z e r  (Burkett 1976) .  The primary r o l e o f t h e  KF i s t o c o n t r a c t e c c e n t r i c a l l y d u r i n g t h e l a t t e r p o s i t i o n o f the swing phase, d e c e l e r a t i n g t h e lower l e g and t h i g h u n t i l t h e l e g swing i s h a l t e d at a p o i n t approximately 30° from t e r m i n a l extension  (Stanton & Purdam 1989, Sutton  1984).  It i s d u r i n g t h i s l a t e swing phase, w h i l e t h e KF a r e e c c e n t r i c a l l y c o n t r a c t i n g , t h a t Sutton  (1984) suggests as one  of the p o i n t s d u r i n g running t h a t hamstring MSI i s l i k e l y t o occur.  Stanton & Purdam  (1989) quote Wood as r e p o r t i n g peak  torque v a l u e s o f 150 Nm at t h e knee and 250 Nm a t t h e h i p d u r i n g t h i s phase o f running.  Torques  such as these a r e known  t o l i m i t how l a t e i n recovery t h a t t h e KF can d e c e l e r a t e t h e  l e g , making them prone t o s t r a i n  (Stanton  & Purdam 1989).  Ghena et a l . (1991) and K l o p f e r & G r e i j (1988) have s t a t e d t h a t the KF are, on average, weaker than the KE. cocontraction  Because t h i s  has opposing f o r c e s the weaker muscle(s) must  'give'; thus r e s u l t i n g i n MSI i f s u f f i c i e n t asymmetry between these two groups o f muscles e x i s t s .  A further c h a r a c t e r i s t i c  o f the knee f l e x o r s i s t h a t , l i k e most b i a r t i c u l a r muscles, they have no i n t r i n s i c mechanism t o l o c a l i z e t h e i r t o only one j o i n t .  contraction  I t i s t h e r e f o r e p o s s i b l e f o r them t o exceed  t h e i r c a p a c i t y t o s t r e t c h ; the r e s u l t being MSI. Other s t u d i e s have a l s o r e p o r t e d the consequence(s) o f such an asymmetry e x i s t i n g between the KF and KE (Arge 1985, Sanderson e t a l 1984, Sutton 1984). the s t r e n g t h  Arge  (1985) s t a t e d t h a t i f  o f the KF i s low i n comparison t o the KE, t h e  f o r c e o f c o n t r a c t i o n may be i n s u f f i c i e n t t o counteract t h e f o r c e o f knee e x t e n s i o n  i n the swing phase o f g a i t or t o p r o -  v i d e adequate h i p e x t e n s i o n  i n the stance phase.  T h i s would  r e s u l t i n an o v e r s t r e t c h i n j u r y or MSI t o the hamstring u n i t . Burkett  (1970) suggested t h a t asymmetry between these two  groups o f muscles, the KE and KF, was a c a u s a t i v e hamstring MSI.  factor i n  He a l s o s t a t e d , however, t h a t not everyone who  possesses a muscle asymmetry w i l l experience a hamstring MSI. Unfortunately,  one o f the l i m i t a t i o n s when t r y i n g t o  r e l a t e the r e s u l t s o f i s o k i n e t i c t e s t i n g t o a c t u a l movement i s t h a t one assumes t h a t muscle c o n t r a c t s at the same v e l o c i t y as the  limb,  a second b e i n g  t h a t i s o k i n e t i c dynamometers are not  yet capable o f measuring torque at those angular v e l o c i t i e s  which occur d u r i n g a t h l e t i c a c t i v i t y .  Klopfer & Greij  (1988)  quote o t h e r s as r e p o r t i n g t h a t v a r i o u s f u n c t i o n a l and  sporting  a c t i v i t i e s have angular v e l o c i t i e s e s t i m a t e d t o range  from  2000 deg/sec"-'-:  700-  s p r i n t i n g having angular v e l o c i t i e s of approx-  i m a t e l y 800-1000 deg/sec"-^ while walking has been r e p o r t e d t o occur at 233 deg/sec"^  ( S t a f f o r d & Granna 1984).  TORQUE PRODUCTION AND In examining  MUSCLE FIBRE COMPOSITION  torque produced by the knee f l e x o r s  and  extensors d u r i n g i s o k i n e t i c t e s t i n g many s t u d i e s have a l s o examined the composition of muscle f i b r e type i n t h e i r s u b j e c t s t o see i f r e l a t i o n s h i p s between these two v a r i a b l e s muscle f i b r e type) e x i s t . a t h l e t e s such as weight who  perform  (torque and  T h i s r e s e a r c h has shown t h a t  lifters,  s p r i n t e r s , and jumpers; those  f a s t c o n t r a c t i o n s with h i g h t e n s i o n s , have a  g r e a t e r percentage  of f a s t t w i t c h . Type I l / n o n - o x i d a t i v e as  compared t o slow t w i t c h . Type I / o x i d a t i v e muscle f i b r e s i n the same l e g muscle  ( C o s t i l l et a l . 1976,  Melichna et a l , 1989,  Thorstensson et a l . 1976b). Thorstensson et a l . (1976b) i n examining found a c o r r e l a t i o n of r= 0.50  a c t i v e maies  between muscle performance  measured by i s o k i n e t i c c o n c e n t r i c c o n t r a c t i o n s at f i v e ent angular v e l o c i t i e s and Type II muscle f i b r e .  as  differ-  They a l s o  found t h a t motor u n i t s demonstrating h i g h e r t e n s i o n outputs s h o r t e r c o n t r a c t i o n times were shown t o c o n t a i n muscle  and  fibre  t h a t c o u l d be c l a s s i f i e d as Type II w i t h t h e i r h i s t o c h e m i c a l techniques.  They concluded t h a t a h i g h percentage  of Type II  muscle f i b r e i s one p r e r e q u i s i t e f o r performing f a s t c o n t r a c t ions w i t h s i m i l a r t e n s i o n outputs. In 1977,  Thorstensson and c o l l e a g u e s r e p o r t e d i n t h e i r  review of the l i t e r a t u r e t h a t endurance event a t h l e t e s have a predominance of Type I muscle f i b r e and t h a t VO2 max  has been  shown t o be p o s i t i v e l y c o r r e l a t e d with the percentage fibre.  of Type I  They a l s o mentioned t h a t with endurance t r a i n i n g the  a e r o b i c p o t e n t i a l and the r e l a t i v e area of Type I f i b r e s have been r e p o r t e d t o i n c r e a s e , predominantly  r e c r u i t e d d u r i n g con-  t r a c t i o n s o f low t e n s i o n outputs. Type II f i b r e s , however, have a m e t a b o l i c p r o f i l e t h a t f a v o r s anaerobic energy p r o d u c t i o n and appear t o only be r e c r u i t e d when h i g h t e n s i o n and/or v e l o c i t y are r e q u i r e d .  Examining  sprinters,  jumpers, d o w n h i l l s k i e r s ,  race walkers, o r i e n t e e r s , and a group of sedentary men,  they  found t h a t : 1) s k e l e t a l muscle of endurance t r a i n e d  athletes  possessed a predominance of Type I f i b r e s 2) peak torque per Kg of body weight  of endurance  a t h l e t e s were s i m i l a r t o those o f sedentary 3) a h i g h e r percentage ers/jumpers  men  o f Type II f i b r e s i n s p r i n t -  (X=61%) as compared t o sedentary  (X=56%) and endurance a t h l e t e s  (X^-^nge^ 33-41%) .  They concluded t h a t the percent d i s t r i b u t i o n o f muscle f i b r e type i s g e n e t i c a l l y determined al.  as shown by G o l l n i c k et  (1973) and Thorstensson et a l . (197 6a) and t h a t Type II  f i b r e s are of s i g n i f i c a n c e f o r h i g h  force production  h i g h speeds of movement.  would expect t h a t among  Thus, one  during  e l i t e a t h l e t e s i n h i g h power events such as s p r i n t i n g and jumping, " n a t u r a l s e l e c t i o n " would have l e f t high proportion skill  only those with a  of Type II f i b r e s capable of competing at  high  levels. Thorstensson et a l . (1976a) performed an e i g h t week t r a i n -  ing  study which r e s u l t e d i n a s i g n i f i c a n t  dynamic s t r e n g t h . vastus l a t e r a l i s , Type I and  By  comparing pre-post  increase i n isometric muscle b i o p s i e s of  they found t h a t the percent  d i s t r i b u t i o n of  Type II muscle f i b r e s were not a l t e r e d which was  accordance w i t h other (Edgerton 1969)  and  the  t r a i n i n g s t u d i e s performed on  in  animals  i n humans ( G o l l n i c k et a l . 1973).  It  was  n o t i c e d however, t h a t the r e l a t i v e volume of f i b r e types i n muscle was  a l t e r e d by  a change i n the Type I-Type I I  area  r a t i o s which i n c r e a s e d with t h i s s t r e n g t h t r a i n i n g p r o t o c o l . Such a d i s c o v e r y Type II f i b r e s can  i n d i c a t e s t h a t s e l e c t e d hypertrophy  occur with t r a i n i n g .  number of f i b r e s does not  the  s i g n i f i c a n t l y change, the s i z e of  those f i b r e s a l r e a d y present stimuli.  Thus although  of  increases  i n response t o t r a i n i n g  They concluded that the r e s u l t s support the i d e a t h a t  f i b r e d i s t r i b u t i o n i s governed l a r g e l y by g e n e t i c f a c t o r s . C o s t i l l et a l . (1976) a l s o support t h i s l i n e o f thought. In t h e i r d i s c u s s i o n they d e s c r i b e d  an e a r l i e r study performed  by G o l l n i c k et a l . (1973) which r e p o r t e d t h a t f i b r e  distribu-  t i o n remained unchanged i n a d u l t males f o l l o w i n g a f i v e month t r a i n i n g program which i n v o l v e d the p e d a l l i n g o f a b i c y c l e  e r g o m e t e r f o r one  h o u r / d a y , f o u r t i m e s / w e e k a t an  75-90% o f t h e i r maximal a e r o b i c  c a p a c i t y . However t h e  c a p a c i t i e s of both f i b r e types increased. gested life  intensity  Costill  of  oxidative  et a l . sug-  t h a t c o n t r a c t i l e c h a r a c t e r i s t i c s are developed e a r l y i n  through genetics  and  muscle f i b r e s adapt t o Melichna  max,  qualities  of  exercise.  e t a l . (1989) a l s o r e p o r t e d  s h i p b e t w e e n VO2 activities  only the metabolic  a positive relation-  t h e p e r c e n t a g e o f Type I f i b r e s ,  of mitochondrial  enzymes.  and  O t h e r t e s t s h a v e shown a  r e l a t i o n s h i p w i t h Type I I m u s c l e f i b r e s and  performance  i t i e s that include v e r t i c a l  and  strength  jumping a b i l i t y  (Vandewalle et a l . 1987).  showed t h a t t h o s e i n d i v i d u a l s who power a c t i v i t i e s p e r f o r m e d b e s t p a r e d t o e n d u r a n c e and  the  The  activ-  quadricep  Vandewalle et a l . study  participated in sprint in vertical  and  j u m p i n g when com-  recreational athletes.  KNEE FLEXION-EXTENSION ASSESSMENT The  c o n c e p t t h a t a t h l e t e s , who  a r e deemed t o be  of high  risk,  p a r t i c i p a t e i n sports  a c h i e v i n g and  maintaining  d e s i r a b l e KF-E  r a t i o t o p r e v e n t p o s s i b l e h a m s t r i n g MSI  debated i n the  literature  f o r the past  e t a l . 1981,  Burkett  1984,  Heiser  e t a l . 1984,  1986,  S a n d e r s o n e t a l . 1984,  1981).  I t was  c o n c e n t r i c KF-E 60 deg/sec"-'-.  1970,  decades  G i l l i a m e t a l . 1979,  S c u d d e r 1980,  o f 0.60  C o p l i n i n 1971,  o r 60% as  who  a  has  been  (Arvidsson  Grace et a l .  Holmes & A l d e r i n k 1984,  K l e i n & A l l m a n i n 1969 ratio  two  which  Oberg et a l .  Wyatt & Edwards first  reported  a  at a t e s t i n g v e l o c i t y  r e p o r t e d by  several  of  authors.  was  the  f i r s t t o recommend t h a t a r a t i o of 60%  the knee e x t e n s o r s and  f l e x o r s t o prevent p o s s i b l e  i n v o l v i n g the hamstrings suggesting  collected.  i t was  The  from 39 t o 85% et a l . 1979, Alderink  1984,  Grace et a l . 1984,  these data were  r a t i o has been r e p o r t e d t o  (Cooper & F a i r 1978,  Ghena et a l . 1991,  Heiser  M o f f r o i d et a l . 1969,  Sanderson et a l . 1984,  knee.  not mentioned as to how  c o n c e n t r i c KF-E  MSI  t h a t such a r a t i o would  minimize the amount of s t r e s s p l a c e d on the Unfortunately  e x i s t between  et a l . 1984,  Oberg et a l .  Smith et a l . 1981,  vary  Gilliam  Holmes & 1986,  Watkins & H a r r i s  1983). Sanderson and unable t o c o n f i r m previously. 62%  colleagues  (1984) and  Scudder  (1980) were  s i m i l a r r e s u l t s as those s t u d i e s mentioned  Scudder found and  reported  a concentric ratio  of  even when i n c r e a s i n g angular v e l o c i t i e s were used with  nonathletic subjects.  Sanderson et a l . r e p o r t e d  r a t i o s averaging around 44%  using  angular v e l o c i t i e s i n 18-25  year o l d male and  athletic  60 and  180  concentric  deg/sec"-"- as female  non-  subjects.  It i s Sanderson et a l . who  suggested t h a t the  difference  found between t h e i r work and that performed p r e v i o u s l y i s t h a t w h i l e the others  d i d not take i n t o account the weight of  the  lower l e g , f o r the e f f e c t ( s ) of g r a v i t y , t h e i r study d i d .  They  a l s o found t h a t when the r a t i o s t h a t were measured d u r i n g  their  study were l e f t u n c o r r e c t e d obtained  f o r g r a v i t y the torque  resembled those of p r e v i o u s  i n c r e a s i n g c o n c e n t r i c KF-E  studies.  readings  That i s ,  r a t i o s with increasing v e l o c i t i e s .  When a g r a v i t a t i o n a l c o r r e c t i o n f a c t o r was c a l c u l a t e d  little  d i f f e r e n c e e x i s t e d between torques at the d i f f e r e n t speeds. In a more recent  study Ghena et a l . (1991) examined the  torque c h a r a c t e r i s t i c s of the knee extensors and f l e x o r s concentric athletes  and e c c e n t r i c l o a d i n g  (18-25 y r s ) .  sprint-type a c t i v i t i e s .  during  i n 100 male u n i v e r s i t y v a r s i t y  Of these s u b j e c t s ,  60 were i n v o l v e d i n  Measuring c o n c e n t r i c a l l y at 60, 120,  300, and 450 deg/sec"-'- and e c c e n t r i c a l l y at 60 and 120 deg/ sec"-"- t h e i r r e s u l t s i n d i c a t e d : 1) c o n c e n t r i c  KF and KE torque decreased w i t h  i n c r e a s i n g angular v e l o c i t y , the KF d e c r e a s i n g a slower r a t e w h i l e e c c e n t r i c torque 2) c o n c e n t r i c  KF-E r a t i o s i n c r e a s e d  v e l o c i t y increased  increased  as angular  while e c c e n t r i c r a t i o s  remained unchanged 3) e c c e n t r i c r a t i o s were g r e a t e r ones at the same v e l o c i t i e s  than  concentric  at  FAULTS WITH PREVIOUS RELATED RESEARCH The problem w i t h p r e v i o u s r e s e a r c h i s t h a t s e v e r a l proced u r a l and t h e o r e t i c a l e r r o r s have been r e v e a l e d as t h i s area expands and t e s t i n g equipment i s improve.  1) e x c l u s i v e measurement  These i n c l u d e :  of concentric  contractions  2) h i p angle and s u b j e c t p o s i t i o n d u r i n g t e s t i n g 3) l a c k o f g r a v i t y  correction  4) time t o reach p r e - s e t angular v e l o c i t y 5) i n c l u s i o n o f f a t mass when examining torque per k i l o g r a m o f body weight  E x c l u s i v e measurement  of concentric  contractions  To date, t h e m a j o r i t y o f experiments have examined only the c o n c e n t r i c c a p a b i l i t i e s o f the KF, KE, and t h e i r  ratios;  t r y i n g t o r e l a t e these measures t o the frequency and i n c i d e n c e of hamstring MSI.  Although i s o k i n e t i c dynamometers  which have  the a b i l i t y t o measure e c c e n t r i c muscular c o n t r a c t i o n such as the Kin-Com have e x i s t e d f o r the past h a l f decade, r e s e a r c h has s t i l l been performed c o n c e n t r i c a l l y when examining F-E r a t i o s of the knee.  Such i s o l a t e d r e s e a r c h does not a i d i n t h e under-  s t a n d i n g o f e c c e n t r i c i s o k i n e t i c c h a r a c t e r i s t i c s o f the knee f l e x o r s and extensors which p r e v i o u s l y has been s t a t e d as an area o f p o s s i b l e weakness p r e d i s p o s i n g hamstring MSI, e s p e c i a l ly i n sprinters.  Kramer & MacDermid  (1989) have examined the  e c c e n t r i c c h a r a c t e r i s t i c s o f the knee e x t e n s o r s i n p r e v i o u s l y u n i n j u r e d young females,  Ghena et a l .  (1991) have measured  torque produced both 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 o f t h e knee f l e x o r s and extensors i n male u n i v e r s i t y a t h l e t e s , and Klopfer & Greij  (1988) i n p r e v i o u s l y u n i n j u r e d u n t r a i n e d males  and females, but such i n v e s t i g a t i o n i s r a r e .  Hip angle and s u b j e c t p o s i t i o n i n g d u r i n g t e s t i n g P r e v i o u s s t u d i e s have examined t h e i r s u b j e c t s i n a supine o n l y p o s i t i o n f o r both KF and KE torque measurements. examination  To make  o f s u b j e c t s as s p o r t s p e c i f i c as p o s s i b l e then  p o s i t i o n i n g d u r i n g data c o l l e c t i o n must a l l o w t h e examined muscle (s)  t o perform as they would d u r i n g a t h l e t i c c o m p e t i t i o n .  W o r r e l l e t a l . (1990) examined i s o k i n e t i c torque by t h e KF i n both supine and prone t e s t p o s i t i o n s .  produced  They found  average torque t o be g r e a t e r i n t h e prone t e s t i n g p o s i t i o n when t r i a l s  were performed  than  supine and t h a t e c c e n t r i c torque was  g r e a t e r than c o n c e n t r i c torque i n t h e prone t r i a l s .  They  concluded t h a t t h e prone p o s i t i o n allows maximal f o r c e  develop-  ment o f t h e KF w h i l e m a i n t a i n i n g muscle l e n g t h - t e n s i o n r e l a t i o n s h i p s s i m i l a r t o what occurs d u r i n g running.  They a l s o  s t a t e d t h a t such a t e s t i n g p o s i t i o n should be used when e v a l u a t i n g KF torque f o r a c t i v i t y .  I t was a l s o mentioned t h a t  d u r i n g s p r i n t i n g t h e KF are 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 and e c c e n t r i c a l l y at both t h e knee and h i p j o i n t s and i t appears t h a t t h i s s i t u a t i o n can c l o s e l y be s i m u l a t e d i n prone t e s t i n g . A l s o with t h e area o f s u b j e c t p o s i t i o n i n g i s t h e degree o f hip  f l e x i o n which i s maintained d u r i n g data  W o r r e l l , P e r r i n & Denegar  collection.  (1989) r e p o r t e d t h a t c l o s e examin-  a t i o n of KF  and  KE  r o l e during a t h l e t i c p a r t i c i p a t i o n  i t s s t r e n g t h i s more a p p r o p r i a t e l y  a s s e s s e d from a supine  p o s i t i o n of 10°  of h i p  saying that  knee f l e x o r p o s i t i o n d u r i n g a t h l e t i c p a r t i c -  the  flexion.  indicates  They quote Mann (1982)  i p a t i o n i s best a s s e s s e d with h i p  Lack of g r a v i t y Correcting  for gravity  i s another important o v e r s i g h t Knowing t h a t  i n a supine t e s t p o s i t i o n not t r a n s d u c e r arm,  s u p p o r t i n g of the motion one then the a l s o be  part  only must f o r c e be  but  for t h i s action.  s a i d d u r i n g the  of the  assistance  I f not  corrected  a v a l i d measure. A  The  h i n d e r s those r e s u l t s of the KE. then g r a v i t y problems are the  and  gravity.  This  lower l e g i n knee f l e x i o n KF  and  With prone t e s t i n g of the  same as i n supine KE  KF  testing.  f a c t o r s have been r e p o r t e d by Hart et a l .  Sanderson et a l . ( 1 9 8 4 ) , both c i t i n g methods used  Winter et a l . ( 1 9 8 1 ) .  However, Nelson & Duncan  suggested a c o r r e c t i o n a l the  same can  correction  enhances those torque measurements o b t a i n e d f o r the  (1984)  for  lower l e g i n  ground n a t u r a l l y by  i n the p r o p u l s i o n of the  Such c o r r e c t i o n  and  i n t o the v a l u e o b t a i n e d d u r i n g t h i s  t e s t because the weight of the  e x t e n s i o n i s drawn t o the  raising  e n t i r e range of  knee f l e x i o n phase.  calculated  e x e r t e d to  i s a l s o used i n the  torque recorded i s not  by  d u r i n g knee e x t e n s i o n  lower l e g throughout the  must c o r r e c t  f a c t o r must be  f l e x i o n of 0-10°.  correction  many p r e v i o u s r e s e a r c h e r s .  p r o p e l the  as  f a c t o r f o r f l e x i o n and  knee which i s l e s s c o s t l y and  has  the  (1983)  have  e x t e n s i o n at  same r e l i a b i l i t y  as  by  those suggested by Winter. as the Kin-Com have b u i l t  Newer i s o k i n e t i c dynamometers i n t o t h e i r software g r a v i t y  such  correct-  i o n equations, thus a l l o w i n g instantaneous c o r r e c t i o n s t o be computed.  Time t o reach p r e - s e t angular v e l o c i t y I s o k i n e t i c assessment o f KF-E torque has, i n the past, not c o n s i d e r e d the i n f l u e n c e of a c c e l e r a t i o n i n the c o l l e c t e d data. Kannus  (1991) r e p o r t e d t h a t p r e v i o u s i s o k i n e t i c e v a l u a t i o n of  peak torque i s a f f e c t e d by the time i t takes the p r e - s e t angular v e l o c i t y t o be reached thus c a u s i n g a f a l s e change i n the angle at which peak torque o c c u r s . must f i r s t  The limb t o be t e s t e d  achieve the v e l o c i t y t h a t has been  b e f o r e t r u e r e s u l t s can be measured.  predetermined  The g r e a t e r the angular  v e l o c i t y o f the t e s t , the longer i t takes f o r the limb t o attain terminal velocity Kannus  (Kannus 1 9 9 1 , Jensen et a l . 1 9 9 1 ) .  (1991) s t a t e d t h a t with i s o k i n e t i c t e s t i n g  people  who posses h i g h l e v e l s o f s t r e n g t h and power c h a r a c t e r i s t i c s , such as e l i t e a t h l e t e s , may be able t o work e f f e c t i v e l y at extreme knee a n g l e s .  He f u r t h e r s t a t e d t h a t they are b e t t e r  a b l e t o achieve a maximal e f f o r t much q u i c k e r a f t e r b e g i n n i n g movement and are capable of m a i n t a i n i n g t h i s h i g h l e v e l o f e f f o r t u n t i l the end of the ROM measured torque curve.  thus changing the shape o f the  He suggested t h a t t h i s a b i l i t y  i s due  t o an a t h l e t e ' s s u p e r i o r r e a c t i o n time and n e u r a l c o n t r o l of the c o n t r a c t i n g muscles as compared t o n o n a t h l e t i c or people w i t h knee j o i n t  injury  .  individuals  P i e t t e e t a l . (1986) found  t h a t d u r i n g c o n c e n t r i c knee extensor  c o n t r a c t i o n s torque  s i g n i f i c a n t l y i n c r e a s e d d u r i n g the f i r s t and the f i r s t  was  15° a t 180 deg/sec"-'-  5° at 30 deg/sec"^ when 0, 50, and 100% maximal  voluntary isometric contractions  (MVIC's) were used as p r e - l o a d  forces. In t h e i r review o f the l i t e r a t u r e Jensen e t a l . (1991) r e p o r t e d t h a t one o f the f e a t u r e s o f the Kin-Com i s s t a t i c l o a d i n g which r e q u i r e s the s u b j e c t t o f i r s t s e l e c t e d f o r c e t o the t r a n s d u c e r R e f e r r i n g t o Gransberg & Knuttson  pre-  apply an o p e r a t o r -  arm b e f o r e motion i s allowed. (1983), they  suggested t h a t  s t a t i c p r e - l o a d i n g c o u l d be used as a method o f a l l o w i n g a more accurate measurement o f maximal dynamic muscle performance at the b e g i n n i n g  o f motion.  P i e t t e e t a l . (1986) examined d i f -  f e r e n t p r e - l o a d i n g l e v e l s at two speeds:  30 and 180 deg/sec"-'-.  I t was Jensen e t a l . (1991) who s t a t e d t h a t such an i n c r e a s e i n the torque produced d u r i n g the e a r l y phase o f t h e t e s t i n g range as a r e s u l t o f p r e - l o a d i n g w i l l a f f e c t the whole-curve a n a l y s i s by i n c r e a s i n g the area under the torque  curve.  To f u r t h e r i n v e s t i g a t e the e f f e c t s o f p r e - l o a d i n g , et  Jensen  a l . (1991) examined c o n c e n t r i c and e c c e n t r i c KE performance  u s i n g two s t a t i c p r e - l o a d l e v e l s .  Using a t e s t ROM from 100-  30° o f knee f l e x i o n and p r e - l o a d f o r c e of 50N and 75% o f MVIC, they  found when the 75% MVIC p r e - l o a d was used q u i c k e r t e n s i o n  development and g r e a t e r torque was produced f o r the f i r s t 15° c o n c e n t r i c a l l y and f o r the f i r s t  20° e c c e n t r i c a l l y than what  was measured u s i n g the 50N p r e - l o a d f o r c e .  Once predetermined  angular v e l o c i t y was a t t a i n e d no s i g n i f i c a n t d i f f e r e n c e s  between the two p r e - l o a d l e v e l s were found t o e x i s t .  They a l s o  r e p o r t e d t h a t the i n i t i a l h i g h e r l e v e l o f t e n s i o n development allows the muscle t o q u i c k l y work c l o s e r t o i t s maximal l e v e l of f i b r e r e c r u i t m e n t and thus an i n c r e a s e i n the average  torque  and concluded t h a t by u s i n g a percentage of each s u b j e c t s MVIC as a p r e - l o a d f o r c e , more a c c u r a t e t e s t i n g can take p l a c e and a more g r a d u a l r i s e t o peak torque with h i g h p r e - l o a d l e v e l s  can  occur.  I n c l u s i o n of f a t mass when torque c o r r e c t e d f o r body weight When p r e v i o u s s t u d i e s examined the i n f l u e n c e of body weight per k i l o g r a m on the amount of torque t h a t was  a b l e t o be  produced by the KF and KE they d i d not account f o r the amount of adipose t i s s u e , bone, and s k i n adding t o the weight subject.  of each  A more a p p r o p r i a t e method would be t o measure the  mass of s k e l e t a l muscle of each i n d i v i d u a l and r e l a t e t h i s body mass t o the amount o f torque t h a t c o u l d be  lean  produced.  Muscle, not adipose i s r e s p o n s i b l e f o r p r o d u c i n g f o r c e s which a l l o w motion  and t h e r e f o r e , should be measured so t h a t  i n v e s t i g a t i o n can be  such  performed.  A n o n i n v a s i v e method of c a l c u l a t i n g muscle mass was d e v e l oped by M a r t i n et a l . (1990) . measuring  They suggested t h a t a method of  s k e l e t a l muscle would be u s e f u l when examining  l e v e l a t h l e t e s s i n c e a t h l e t e s of d i f f e r e n t  s p o r t s may  elite-  vary  between muscle mass and f a t mass. In the examination of twelve male cadavers they performed  (aged  50-94),  the f o l l o w i n g anthropometric measurements:  skinfold thickness at triceps, thigh,  subscapular, biceps,  anterior  a n d m e d i a l c a l f a n d c i r c u m f e r e n c e m e a s u r e m e n t s t a k e n on  the forearm,  arm, t h i g h ,  and medial c a l f .  Limb g i r t h s  were  then c o r r e c t e d f o r s k i n f o l d thickness using the c i r c u l a r of t h e limb c r o s s - s e c t i o n and limb muscle g i r t h s  model  estimated.  They t h e n d i s s e c t e d a n d w e i g h e d a l l s k e l e t a l m u s c l e ,  free of  skin,  girth  a d i p o s e t i s s u e , bone, o r organs f i n d i n g s i m p l e  c o r r e l a t i o n c o e f f i c i e n t s o f r = 0.824-0.942.  When c o r r e c t e d f o r  t h e s k i n f o l d measurement t h e s e i n c r e a s e d t o r = 0.896-0.990. They d e t e r m i n e d  t h a t from t h e s e r e s u l t s t h a t t h e two b e s t  p r e d i c t o r s o f m u s c l e mass w e r e f o r e a r m c i r c u m f e r e n c e and m i d - t h i g h c i r c u m f e r e n c e  (r^= 0.93)  ( r ^ = 0.89) w h i c h w e r e i n c r e a s e d  when s k i n f o l d - c o r r e c t e d c i r c u m f e r e n c e s w e r e They d e c i d e d t h a t i n o r d e r t o r e d u c e  used.  sampling e r r o r a  t h i r d variable should enter t h e i r prediction equation, ed c a l f g i r t h and thus developed  correct-  the following equation:  MM= STAT (0.0553 CTG^ + 0.0987 F<^ + 0.0331 CCG^) - 2445 w h e r e MM i s t h e t o t a l  s k e l e t a l m u s c l e mass  ( g ) , STAT i s s t a t u r e  (cm), CTG i s t h i g h c i r c u m f e r e n c e c o r r e c t e d f o r t h e a n t e r i o r t h i g h s k i n f o l d t h i c k n e s s (cm), FG i s t h e u n c o r r e c t e d  forearm  c i r c u m f e r e n c e , a n d CCG i s c a l f c i r c u m f e r e n c e c o r r e c t e d f o r t h e medial c a l f s k i n f o l d thickness  (cm).  Chapter 3 PROCEDURES  METHODOLOGY A t o t a l o f s i x t y males aged 18-35, having no p r e v i o u s history  o f lower e x t r e m i t y muscle or j o i n t i n j u r y ,  as s u b j e c t s .  A f t e r being informed  each t e s t procedure  volunteered  of the r i s k s a s s o c i a t e d with  and t h e i r consent  given, s u b j e c t s were  evenly separated i n t o t h r e e groups dependant upon t h e i r logical test  physio-  results.  TESTING PROCEDURES A l l p h y s i o l o g i c a l measures were performed at t h e Buchanan E x e r c i s e Science Laboratory  l o c a t e d at t h e A q u a t i c Centre, UBC  while torque measurements were performed on t h e Kin-Com i s o k i n e t i c dynamometer  (Kin-Com, Med-Ex D i a g o n s t i c s o f Canada,  Inc., 51 Leeder Ave., Coquitlam,  B.C., V3K 3V5) l o c a t e d at the  s c h o o l o f R e h a b i l i t a t i o n Medicine,  Pathokinesiology  Laboratory  at the Acute Care H o s p i t a l , UBC. The  initial visit  i n c l u d e d t h e r e c o r d i n g o f each i n d i v i d -  u a l ' s h e i g h t , weight, and anthropometric d e s c r i b e d by M a r t i n e t a l . (1990). j e c t s were allowed t o perform  measurements as  Once t h i s was complete sub-  a s e l f designed warm-up u n t i l  they were ready t o proceed. The v e r t i c a l jump t e s t c o n s i s t e d o f each s u b j e c t i n g t h r e e s t a n d i n g v e r t i c a l jumps as d e s c r i b e d by & Jackson  (1987).  perform-  Baumgartner  The VO2 max t e s t r e q u i r e d each s u b j e c t t o  r u n a t an i n i t i a l  v e l o c i t y o f 8.05  km/hr w i t h 0.805 km/hr  i n c r e a s e s i n v e l o c i t y e v e r y m i n u t e t h e r e a f t e r a s d e s c r i b e d by Parkhouse  e t a l . (1985).  m i n u t e mark and was increment mill  I f a subject reached the  sixteen  able to continue then the next  c o n s i s t e d o f an i n c r e a s e i n t h e g r a d e  o f two p e r c e n t and w o u l d i n c r e a s e by two  minute t h e r e a f t e r u n t i l  exhaustion.  workload  of the  percent  M e t a b o l i c gas  treadevery  analysis  was  d a t a a n a l y z e d u s i n g t h e H e w l e t t P a c k a r d m o d e l 3052-A d a t a a c q u i s i t i o n system. c preceded  VO2  A second  max  For a l l subjects the v e r t i c a l  jump t e s t  assessment.  visit  was  the grouping c r i t e r i a  r e q u i r e d by t h o s e i n d i v i d u a l s who  met  and c o n s i s t e d o f an i s o k i n e t i c e v a l u -  a t i o n o f t h e d o m i n a n t l i m b ' s k n e e f l e x o r s and  extensors.  I s o k i n e t i c e v a l u a t i o n i n c l u d e d t h e measurement o f  average  t o r q u e o f t h e d o m i n a n t l i m b k n e e f l e x o r s and e x t e n s o r s d u r i n g f i v e maximum c o n t i n u o u s c o n c e n t r i c a n d e c c e n t r i c c o n t r a c t i o n s from  85-15° a t a n g u l a r v e l o c i t i e s o f 90,  sec"-'-.  135,  and  180  A f t e r p e r f o r m i n g a s e l f d e s i g n e d warm-up t h e  l i m b o f each  s u b j e c t was  determined  by a s k i n g w h i c h  would p r e f e r t o k i c k a soccer b a l l w i t h . initially  p l a c e d i n a supine p o s i t i o n  deg/ dominant  l e g they  S u b j e c t s were  f o r the examination  t h e k n e e e x t e n s o r s and t h e n i n a p r o n e p o s i t i o n  f o r the  of  knee  f l e x o r s s u c h t h a t a h i p a n g l e o f 10° was  maintained during data  collection  s t e p was  lateral  f o r both positions.  The  f e m o r a l e p i c o n d y l e w h i c h was  a x i s o f t h e K i n - C o m ' s t r a n s d u c e r arm  next  to locate  used t o v i s u a l l y  align  to the anatomical axis  the the of  the knee as d e s c r i b e d by Kramer & MacDermid  (1989).  of each s u b j e c t ' s f i b u l a on the dominant l e g was The end,  l e g pad was  on the f o r c e transducer,  attached  The  length  then measured.  at the  distal  p o s i t i o n e d such t h a t i t corresponded t o 75% o f the  f i b u l a r l e n g t h and then a s t a b i l i z a t i o n s t r a p , t o e x c e s s i v e movement d u r i n g t r i a l s ,  was  limit  p o s i t i o n e d across  the  pelvis. The as was was  t e s t ROM  was  then entered  the angular v e l o c i t y .  i n t o the Kin-Com's computer  Next, a f a m i l i a r i z a t i o n p e r i o d  allowed which c o n s i s t e d of f i v e t r a i l s :  f o l l o w e d by two contractions.  maximal continuous This was  c o n c e n t r i c and e c c e n t r i c  performed p r i o r t o each t r i a l  v e l o c i t y and muscle group.  f o r each  P r i o r t o f a m i l i a r i z a t i o n however,  each i n d i v i d u a l ' s maximal v o l u n t a r y (MVIC) was  t h r e e submaximal  isometric contraction  measured u s i n g the Kin-Com's i s o m e t r i c f e a t u r e .  p r e - l o a d f o r c e used b e f o r e the t r a n s d u c e r  arm  c o l l e c t i o n corresponded t o the 75% MVIC v a l u e as d e s c r i b e d by Jenson et a l . (1991) .  moved d u r i n g  a two  minute r e s t .  f e e l competent were allowed  I f s u b j e c t s were c o n f i -  Those s u b j e c t s who  further practice t r i a l s  f i d e n t and were then given a two G r a v i t y was trials.  arm  using a l e v e l .  they  d i d not until  con-  minute break.  c o r r e c t e d f o r p r i o r t o the commencement of the  T h i s c o r r e c t i o n i n v o l v e d the m a n i p u l a t i o n  transducer  data  f o r each s u b j e c t  dent with t h e i r performance d u r i n g the p r a c t i c e attempts were allowed  The  i n t o a h o r i z o n t a l p o s i t i o n which was This angle was  puter and used f o r r e f e r e n c e .  entered  o f the checked  i n t o the Kin-Com's com-  Then the t r a n s d u c e r  arm  was  p o s i t i o n e d so t h a t the s u b j e c t ' s limb was e x t e n s i o n and  i t was  at t h i s p o i n t t h a t the f o r c e a p p l i e d by  the l e g t o the t r a n s d u c e r arm recorded.  T h i s was  10° from f u l l knee  due t o g r a v i t y was  measured and  performed p r i o r t o the e v a l u a t i o n of each  muscle group. The  order i n which the t r i a l s  o c c u r r e d was  the knee extensors always being the f i r s t  group t e s t e d f o r  t h e i r t h r e e speeds and then the knee f l e x o r s . minimize any a f f e c t t h a t l e a r n i n g may trials.  randomized with  T h i s was  done t o  have on subsequent  In an attempt t o l i m i t the e f f e c t of p o s i t i v e  n e g a t i v e a c c e l e r a t i o n d u r i n g the i s o k i n e t i c t r i a l s  and  only  those  torques produced from 75-30° of knee f l e x i o n were used i n the data a n a l y s i s as shown by Jensen et a l . (1991). Each s u b j e c t was the e x e r c i s e and was the e n t i r e t e s t ROM.  i n s t r u c t e d when t o begin and when t o stop t o l d to g i v e a maximal e f f o r t V e r b a l encouragement was  not g i v e n by  t e s t e r d u r i n g data c o l l e c t i o n and s u b j e c t s were not to view the d i s p l a y monitor support themselves. f u r t h e r two trial  began.  or t o grasp handles  Upon the completion  minute r e s t i n t e r v a l was  throughout the  permitted  to further  of each t r i a l  allowed b e f o r e the  a next  DESIGN AND  CHARACTERISTICS OF THE DATA  One-way randomized groups analyses o f v a r i a n c e were p e r formed when examining the d i f f e r e n c e s between each o f the three groups o f s u b j e c t s f o r p h y s i c a l c h a r a c t e r i s t i c s :  one  f o r each o f h e i g h t , weight, and age), p h y s i o l o g i c a l istics:  one a n a l y s i s f o r each o f VO2 max  (VJ), and anthropometric c h a r a c t e r i s t i c s : each o f s k e l e t a l muscle mass (SMM)  analysis  character-  and v e r t i c a l  jump  one a n a l y s i s f o r  and percent body weight  accounted f o r by s k e l e t a l muscle. Secondly, two analyses o f v a r i a n c e  (ANOVA's) one f o r each  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 : 3  3 ( a t h l e t i c group) X  (angular v e l o c i t i e s ) X 2 (muscle groups) f a c t o r i a l exper-  iments w i t h repeated measures  on the l a s t two f a c t o r s , were  performed. These t h r e e groups were examined at t h r e e d i f f e r e n t angular v e l o c i t i e s :  90, 135, and 180 deg/sec"-"- f o r both the  knee e x t e n s o r s and f l e x o r s . angular v e l o c i t i e s ,  The t h r e e s u b j e c t groups, t h r e e  and two muscle groups were the t h r e e  independent v a r i a b l e s r e s p e c t i v e l y .  The dependent  variables  f o r t h e s e analyses were the torque measured d u r i n g the two d i f f e r e n t types o f c o n t r a c t i o n s which were examined from 75-30° of knee f l e x i o n .  Measured torque was  as  measured  corrected for  s k e l e t a l muscle mass by d i v i d i n g the a b s o l u t e torque by the p e r c e n t body weight t h a t was composed of s k e l e t a l muscle mass which was present i n each s u b j e c t  (Nm/kg c o r r e c t e d ) .  A t h i r d f a c t o r i a l a n a l y s i s was performed t o examine i f d i f f e r e n c e s e x i s t e d between e c c e n t r i c and c o n c e n t r i c ratios.  KF-E  A 3 ( a t h l e t i c group) X 3 (angular v e l o c i t i e s ) X 2  (ratio contraction  types) a n a l y s i s o f v a r i a n c e w i t h repeated  measures on t h e l a s t two f a c t o r s was performed; once again t h e t h r e e l e v e l s o f the f i r s t a t h l e t e s , endurance  independent v a r i a b l e were power  athletes,  and sedentary s u b j e c t s .  second independent v a r i a b l e i n c l u d e d v e l o c i t i e s which the c o n t r a c t i o n s  The  the t h r e e t e s t i n g  occurred at:  90, 135, and  180 deg/sec"-'- and the t h i r d independent v a r i a b l e was c o n c e n t r i c KF-E  and e c c e n t r i c KF-E r a t i o s .  The dependent  variable for  t h i s a n a l y s i s was t h e average torque (Nm/kg c o r r e c t e d ) r a t i o c a l c u l a t e d by d i v i d i n g the knee f l e x o r torque by t h e knee extensor torque as measured from 75-30° o f knee f l e x i o n . L a s t l y , Pearson Product Moment C o r r e l a t i o n  Coefficients  were c a l c u l a t e d t o examine t h e r e l a t i o n s h i p s between torque and vertical  jumping a b i l i t y , VO2 max, and s k e l e t a l muscle mass as  measured a c c o r d i n g t o M a r t i n e t a l . (1990). S t a t i s t i c a l s i g n i f i c a n c e was accepted a t the p< 0.05 l e v e l w i t h s t a t i s t i c a l c a l c u l a t i o n s performed u s i n g the BMDP IV, and BMDP 8D s t a t i s t i c a l packages S t a t i s t i c a l Software 1981)  (BMDP-Biomedical  and Scheffé's  Computer  post hoc p a i r w i s e  analyses were performed f o r a l l s i g n i f i c a n t F r a t i o s .  2V,  Chapter 4 RESULTS AND  DISCUSSION  RESULTS A t o t a l Of 72 i n d i v i d u a l s were p h y s i o l o g i c a l l y e v a l u a t e d f o r maximal oxygen consumption ability.  and v e r t i c a l jumping  Of these, 60 p a r t i c i p a t e d as s u b j e c t s i n t h i s study:  20 p e r group. group  (VO2 max)  Of t h e t h r e e groups examined, the power  athlete  (PA) had the most v a r i e d composition with t e n s u b j e c t s  t r a i n - i n g f o r track events  (long,  players,  s p r i n t events  triple,  and/or h i g h ) ,  (50 - 200m), f i v e f o r jumping two were v a r s i t y  and t h r e e p a r t i c i p a t e d i n v a r s i t y hockey.  e r a t e l y a c t i v e group  basketball The mod-  (MA) was comprised o f v a r s i t y g o l f e r s  (N=  12) and people who were p a r t i c i p a t i n g i n p e r s o n a l f i t n e s s activities group  (N= 8 ) .  F i n a l l y , the a e r o b i c a l l y t r a i n e d  (ATR) c o n s i s t e d  runner  o f eighteen i n d i v i d u a l s who were t r a i n i n g  f o r c o m p e t i t i o n d i s t a n c e s of g r e a t e r than 800m (range 800m marathon) and two s u b j e c t s who were t r a i n i n g f o r t r i a t h l o n s .  Physical The  Characteristics means and standard d e v i a t i o n s  groups o f s u b j e c t s p h y s i c a l Table 4.1. ences  f o r each o f t h e t h r e e  c h a r a c t e r i s t i c s can be l o c a t e d i n  In t h i s study t h e r e were no s i g n i f i c a n t d i f f e r -  (p> 0.05) i n h e i g h t between the t h r e e groups even though,  on average, PA were t a l l e r than e i t h e r the ATR or MA groups as seen i n F i g u r e 4.1. i c a n t l y heavier  Although the PA and MA groups were s i g n i f -  (p< 0.001) than the ATR group, the ATR group  was  significantly  older  groups of s u b j e c t s .  (p< 0.001) than e i t h e r o f the other two  For both height and weight t h e r e were no  s i g n i f i c a n t d i f f e r e n c e s between the MA and PA groups  TABLE 4.1  Physical Characteristics x"  PA  sd  ATR X  sd  X  MA  sd  Height(cm)  182.5  4.90  178.6  7.19  179.8  7.56  Weight(kg)  81.6  6.77  70.5  4.48  80.3  8.05  Age{years)  22.2  2.75  27.8  4.07  22.7  3.33  (p> 0.05).  FIGURE 4.1  Group Physical Characteristics  HEIGHT (cm)  WEIGHT (kg)  AGE (years)  182.5  81.6  22.2  178.9  70.5  27.8  179.8  80.3  22.7  Physiological Characteristics The three groups were c l a s s i f i e d u s i n g two physiological evaluations: tests.  the v e r t i c a l  different  jump and the VO2 max  As seen i n Table 4.2 the ATR group had a s i g n i f i c a n t l y  g r e a t e r mean VO2 max score r e l a t i v e  t o body weight  (p< 0.001)  than e i t h e r t h e PA or MA groups who d i d not d i f f e r  (p> 0.05).  However, when v e r t i c a l  jumping a b i l i t y was examined t h e ATR and  MA groups d i d not s i g n i f i c a n t l y group s i g n i f i c a n t l y  out jumped  two groups o f s u b j e c t s .  differ  (p> 0.05) while t h e PA  (p <0.001) e i t h e r o f the other  Graphical representation for t h i s  a n a l y s i s can be l o c a t e d i n F i g u r e 4.2.  TABLE 4.2  Physiological Characteristics PA "x  ATR sd  X  MA Sd  X  sd  V.Jump(cm)  70.7  4.26  48.9  9.44  51.6  5.04  V02max(ml/kg/min)  51.1  2.50  64.4  3.58  49.1  4.15  FIGURE 4.2  Group Physiological Characteristics  Anthropometric  Characteristics  The PA group was s i g n i f i c a n t l y g r e a t e r than e i t h e r the MA (p< 0.01) or ATR (p< 0.001) groups as seen i n Table 4.3 and F i g u r e 4.3, w h i l e the MA group was s i g n i f i c a n t l y g r e a t e r than the ATR group lated.  (p< 0.05) when s k e l e t a l muscle mass was c a l c u -  When body weight was c o r r e c t e d f o r s k e l e t a l muscle,  d e r i v e d by d i v i d i n g s k e l e t a l muscle mass by body weight, the PA group were s i g n i f i c a n t l y g r e a t e r than e i t h e r the MA or ATR  (p< 0.02) groups.  (p< 0.002)  These l a s t two groups were not s i g -  n i f i c a n t l y d i f f e r e n t from each o t h e r .  Graphical  represent-  a t i o n can be l o c a t e d i n F i g u r e 4.3.  TABLE 4.3  Anthropometric Characteristics PA X  Skeletal Muscle Mass(kg) % Body Weight Accounted for by Skeletal Muscle  ATR sd  X  MA Sd  X  Sd  52.4  5.76  42.6  5.43  47.2  6.67  64.2  4.96  60.3  5.61  58.6  4.43  FIGURE 4.3  Anthropometric Characteristics 70.0  SMM . Skeletal Muscle Mass BW - Body Weight  Past s t u d i e s have examined torque produced by the knee f l e x o r s and extensors, measured i s o k i n e t i c a l l y , term: 1991,  newton meters  (Nm) (Bennett  & Stauber  as an absolute  1986, Ghena e t a l .  Hageman e t a l . 1988, Harding e t a l . 1988, Kramer &  MacDermid 1989, P i e t e r e t a l . 1989, S t a f f o r d & Granna 1984, Thorstensson al.  e t a l . 1976, T r e d i n n i c k & Duncan 1988, W o r r e l l e t  1989, W o r r e l l e t a l . 1990), i n foot pounds  (ft/lb)  (Bohannon e t a l . 1986, K l o p f e r & G r e i j 1988, Wyatt & Edwards 1981), and as a r e l a t i v e term:  Nm/kg o f body weight  (Highgenboten e t a l . 1988, Sanderson e t a l . 1984, W o r r e l l e t al.  1991). In t h e present study torque was measured as a r e l a t i v e  term a l s o accounting  f o r body weight:  Nm/kg c o r r e c t e d .  weight was c o r r e c t e d f o r t h e weight which was accounted adipose, bone, and other nonmuscular t i s s u e .  Body f o r by  T h i s was done by  d i v i d i n g t h e a b s o l u t e torque by the percent body weight accounted  f o r by s k e l e t a l muscle as d e s c r i b e d i n t h e p r e v i o u s  a n a l y s i s o f anthropometric  characteristics.  T h e r e f o r e , i n the  f o l l o w i n g s e c t i o n s , c o n c e n t r i c and e c c e n t r i c torque has been c o r r e c t e d f o r s k e l e t a l muscle mass (Nm/kg c o r r e c t e d ) .  C o r r e c t e d C o n c e n t r i c Torque The means and standard d e v i a t i o n s f o r the c o n c e n t r i c knee extensor and f l e x o r torque values produced at t h e t h r e e v e l o c i t i e s are presented F i g u r e 4.4. group  i n Table 4.4 and g r a p h i c a l l y d i s p l a y e d i n  The a t h l e t i c group X angular v e l o c i t y X muscle  (3x3x2) repeated measures ANOVA f o r c o r r e c t e d c o n c e n t r i c  torque r e v e a l e d s i g n i f i c a n t  differences  (F= 1 0 . 6 9 , p< 0 . 0 0 1 )  between t h e t h r e e s u b j e c t groups i n t h e i r torque c o n c e n t r i c a l l y and  a b i l i t y t o produce  when averaged over t h e two muscle groups (3rp^= 2 . 2 8 , 3r^TR" 1-97, l ( j ^ = 2 . 0 4 ) .  t h r e e angular v e l o c i t i e s  A Scheffé's post hoc a n a l y s i s i n d i c a t e d t h a t t h e PA group c o u l d produce s i g n i f i c a n t l y g r e a t e r c o n c e n t r i c torque than c o u l d the ATR (p< 0 . 0 1 ) nificant  and MA groups  differences  A significant  (p< 0 . 0 5 ) ,  w h i l e t h e r e were no s i g -  (p> 0 . 0 5 ) between t h e MA and ATR groups.  muscle main e f f e c t  (F= 1 4 8 9 . 0 8 , p< 0 . 0 0 1 )  i n d i c a t e s t h a t t h e c o r r e c t e d c o n c e n t r i c torque produced was s i g n i f i c a n t l y g r e a t e r f o r t h e KE than t h a t f o r t h e KF when averaged over the t h r e e groups o f s u b j e c t s and t h r e e angular velocities The  ( % E = 2.72,  1.47).  t h i r d and f i n a l main e f f e c t  velocity,  was a l s o s i g n i f i c a n t  for this analysis,  (F= 2 9 8 . 1 8 , p< 0 . 0 0 1 ) .  angular When  averaged over the t h r e e s u b j e c t groups, and two groups o f muscle, the c o n c e n t r i c torque t h a t c o u l d be produced at the three d i f f e r e n t  t e s t v e l o c i t i e s were s i g n i f i c a n t l y  from each other  2.24,  Xi35= 2 . 1 1 ,  X;i^gQ= 1 . 9 4 ) .  different Further  post hoc analyses were performed which i n d i c a t e d t h a t t h e concentric ^180  torque produced f o r X^Q was s i g n i f i c a n t l y g r e a t e r than 0.01)  and X]^35 (p< 0 . 0 5 ) ,  g r e a t e r than X-LQQ  while ^1^5  was s i g n i f i c a n t l y  (p< 0 . 0 1 ) .  Although t h e a t h l e t i c group X angular v e l o c i t y a t h l e t i c group X muscle group X angular v e l o c i t y  and the  interactions  were not s i g n i f i c a n t  (p> 0 . 0 5 ) the other two i n t e r a c t i o n s i n  t h i s a n a l y s i s were.  The s i g n i f i c a n t  muscle group X angular  v e l o c i t y i n t e r a c t i o n , as d i s p l a y e d i n F i g u r e  4.5,  (F= 42.26,  p<  0.001) i n d i c a t e s t h a t when averaged over the t h r e e groups of subjects,  c o n c e n t r i c torque produced by the KE decreased more  r a p i d l y from 90° through 180  deg/sec"-'- than d i d t h a t which  measured f o r the KF over the same v e l o c i t i e s % E 1 3 5 = 2.73, 1.36).  Xj^g280" 2.51  Post hoc  / Xj^pgg^ 1-56,  a n a l y s i s r e v e a l e d t h a t the  1.48,  w h i l e at p< The  > %E180' %E135 0.05  XJ^E90  %F90  > %F180'  s i g n i f i c a n t l y g r e a t e r than "Xj^pisO-  s i g n i f i c a n t muscle group X a t h l e t i c group i n t e r a c t i o n  (F= 4.2 6, p< the KE  y^j<i-pi25  > %E180'  XKP280"  f o l l o w i n g compar-  i s o n s were s i g n i f i c a n t l y d i f f e r e n t at p < O.Ol: '^KE135' % E 9 0  2.91,  i^j^ESO^  ^KFISS"^  was  and  0.02)  KF was  r e v e a l s t h a t c o n c e n t r i c torque produced by s i g n i f i c a n t l y d i f f e r e n t between the  three  groups of s u b j e c t s when averaged over the t h r e e  angular v e l o c i -  ties  / Xj^p_pj^=  (X^E-PA"^ 2.85,  ^KF-ATR~  1*35,  XJ^E-ATR"^  ^ K F - M A " 1-35).  i n d i c a t e d t h a t at p< nificantly  2.58,  different:  0.01  the  ^KE-PA  %E-MA^  Further  2.72  1.70,  Scheffé's a n a l y s i s  f o l l o w i n g r e l a t i o n s h i p s were s i g ^  ^KE-ATR'  ^KF-PA  i c a n t l y g r e a t e r than e i t h e r Xj^p_j^ and % F - A T R a c t i o n i s g r a p h i c a l l y presented i n F i g u r e  4.6.  This  signif-  inter-  TABLE 4.4  Corrected Concentric Torque Athletic Group & Muscle Group PA  ATR  MA  Ang.Velocity (deg/sec-1)  Mean  SD  KE  90 135 180  3.04 2.88 2.62  0.26 0.24 0.26  KF  90 135 180  1.81 1.73 1.56  0.22 0.18 0.19  KE  90 135 180  2.76 2.59 2.40  0.41 0.42 0.43  KF  90 135 180  1.44 1.35 1.25  0.26 0.21 0.22  KE  90 135 180  2.93 2.73 2.51  0.15 0.18 0.31  KF  90 135 180  1.41 1.36 1.28  0.21 0.21 0.21  * significant Athletic Group main effect (F=10.69, p< 0.001 ) * significant Musde Group main effect (F=1489.08, p< 0.001) * significant Angular Velocity main effect (F=298.18, p< 0.001)  FIGURE 4.4  Corrected Concentric Torque Concentric Torque (Nm/kg corr. BW)  KE90  135  180  KF90  135  180  PA  3.04  2.88  2.62  1.81  1.73  1.56  ATR  2.76  2.59  2.40  1.44  1.35  1.25  MA  2.93  2.73  2.51  1.41  1.36  1.28  Muscle Group and Velocity(deg/sec-1)  m  PA  ME  ATR  mi  MA  Corrected for %BW due to Skeletal Muscle  Concentric Torque (Nm/kg corr. BW) 3.00 2.80 2.60 2.40 2.20 2.00 1.80 1.60 1.40 1.20 1.00  90  135  180  KE  2.91  2.73  2.51  KF  1.56  1.48  1.36  Velocity (deg/sec-1) KE  KF  Averaged over the three groups  Concentric Torque (Nm/kg corr.) 3.00 2.80 2.60 2.40 2.20 2.00 1.80 1.60 1.40 1.20 1.00  KE  KF  PA  2.85  1.70  ATR  2.58  1.35  MA  2.72  1.35 Muscle Group PA  + ~ ATR  Averaged over angular velocity  MA  ]  C o r r e c t e d E c c e n t r i c Torque Means and standard d e v i a t i o n s f o r t h e 3 ( a t h l e t i c group) X 2  (muscle  group) X 3 (angular v e l o c i t y ) repeated measures ANOVA  f o r c o r r e c t e d e c c e n t r i c torque are p r e s e n t e d g r a p h i c a l l y r e p r e s e n t e d i n F i g u r e 4.7.  i n Table 4.5 and  This a n a l y s i s revealed  t h a t 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 t h r e e groups o f subjects  (XpA= 2.61, X^TR" 2.22, X^=  2.29) i n t h e i r a b i l i t y t o  produce e c c e n t r i c torque e x i s t when averaged muscle groups and t h r e e angular v e l o c i t i e s 0.001).  over t h e two (F= 12.72, p<  When Scheffé's post hoc analyses were performed i t was  found t h a t the PA group c o u l d produce g r e a t e r e c c e n t r i c torque than c o u l d e i t h e r t h e ATR or MA groups a t t h e p< 0.01 l e v e l o f significance.  However, t h e r e were no s i g n i f i c a n t d i f f e r e n c e s  (p> 0.05) between t h e MA and ATR groups. A s i g n i f i c a n t muscle main e f f e c t indicates that the a b i l i t y torque  (F= 2395.85, p< 0.001)  f o r the KE t o produce e c c e n t r i c  i s s i g n i f i c a n t l y g r e a t e r than t h a t which i s produced by  the KF when averaged s u b j e c t groups  over the t h r e e angular v e l o c i t i e s and  (Xj^g= 3.01, Xj^p= 1.74).  The t h i r d main e f f e c t , angular v e l o c i t y , was not s i g n i f i cant a t p< 0.05 (F= 1.50, p> 0.20).  This i n d i c a t e s that there  were no s i g n i f i c a n t d i f f e r e n c e s i n the c o r r e c t e d e c c e n t r i c torque t h a t c o u l d be produced f o r the t h r e e angular when averaged of muscle  velocities  over the three groups o f s u b j e c t s and two groups  0^90= 2.38, Xi35= 2.37, XIQQ=  2.38).  Only the muscle group X a t h l e t i c s t a t u s i n t e r a c t i o n was significant  (F= 17.01, p< 0.001) i n d i c a t i n g t h a t t h e d i f f e r -  ences between the a b i l i t y o f the KE and KF t o produce  eccentric  torque i s i n f l u e n c e d by the demands o f one's a c t i v i t y when averaged over the t h r e e a n g u l a r v e l o c i t i e s  (%E-PA^  ATR= 2 . 8 8 , X^E-MA" 3 . 0 0 / X ^ p - P A ^ 2 . 0 8 , ^KF-ATR" 1 . 5 8 ) as seen i n F i g u r e 4 . 8 .  3.14,  1.56,  X^FMA^  S i g n i f i c a n t post hoc comparisons  f o r t h i s i n t e r a c t i o n we re found t o e x i s t between X J ^ E — P A MA' ATR  %F-PA  > %F-ATR  X^E-  %F-MA  P < ^'^^  %E-PA  ^KE— > "^KE-  P"^ 0 . 0 5 . The other i n t e r a c t i o n s  group X a n g u l a r v e l o c i t y , interaction,  for this analysis:  a t h l e t i c group X a n g u l a r v e l o c i t y  and the t h r e e way  muscle group X a n g u l a r v e l o c i t y nificant  (p>  0.05).  the muscle  interaction  f o r a t h l e t i c group X  for this analysis  were not  sig-  TABLE 4.5  Corrected Eccentric Torque Athletic Group & Muscle Group PA  ATR  MA  Ang.Velocity (deg/sec-1)  Mean  SD  KE  90 135 180  3.13 3.14 3.14  0.25 0.24 0.27  KF  90 135 180  2.10 2.06 2.09  0.21 0.21 0.22  KE  90 135 180  2.88 2.88 2.88  0.44 0.44 0.45  KF  90 135 180  1.57 1.54 1.57  0.35 0.32 0.32  KE  90 135 180  3.00 2.99 3.00  0.16 0.16 0.15  KF  90 135 180  1.58 1.58 1.59  0.21 0.19 0.20  * significant Atfiletic Group main effect (F=12.72, p< 0.001) * significant Muscle Group main effect (F=2395.85, p< 0.001) * nonsignificant Angular Velocity main effect (F=1.50, p> 0.20)  FIGURE 4.7  Corrected Eccentric Torque Ecœntric Torque (Nm/kg of corr. BW)  Muscle Group and Velocity (deg/sec-1) PA  ATR  MA  Corrected for %BW due to Skeletal Muscle  1  Eccentric Torque (Nm/kg corr.) 3.20 3.00 2.80 2.60 2.40 2.20 2.00 1.80 1.60 1.40  KE  KF  PA  3.14  2.08  ATR  2.88  1.56  MA  3.00  1.58 Muscle Group PA  ATR  Averaged over angular velocity  MA  Knee F-E R a t i o s The  means and standard d e v i a t i o n s  groups) X 3 (angular  for the 3 ( a t h l e t i c  v e l o c i t y ) X 2 ( c o n t r a c t i o n type) repeated  measures ANOVA f o r c a l c u l a t e d c o n c e n t r i c  and e c c e n t r i c KF-E  r a t i o s can be l o c a t e d i n Table 4 . 6 and i s g r a p h i c a l l y sented i n F i g u r e ference  4.9.  (F= 3 2 . 8 5 ,  of s u b j e c t s  This a n a l y s i s found a s i g n i f i c a n t d i f -  p< 0 . 0 0 1 ) t o e x i s t between t h e t h r e e  f o r t h e i r combined c o n c e n t r i c  l a t e d r a t i o s when averaged over t h e t h r e e  had  XMA^ 5 1 . 2 ) .  l e v e l s o f angular  Post hoc analyses r e v e a l e d  combined c o n c e n t r i c  greater  groups  and e c c e n t r i c c a l c u -  v e l o c i t y and two l e v e l s o f c o n t r a c t i o n types 52.8,  repre-  ('Xpj^= 6 3 . 1 , Xj^r[,j^= t h a t t h e PA group  and e c c e n t r i c KF-E r a t i o s t h a t were  than e i t h e r t h e ATR or MA groups a t t h e p< 0 . 0 1 l e v e l  of s i g n i f i c a n c e w h i l e there were no s i g n i f i c a n t d i f f e r e n c e s (p> 0 . 0 5 ) between those r a t i o s c a l c u l a t e d f o r t h e MA and ATR groups. When averaged over the t h r e e groups o f s u b j e c t s  and three  angular v e l o c i t i e s t h e r e were s i g n i f i c a n t d i f f e r e n c e s between concentric p<  0.001).  r a t i o s and those measured e c c e n t r i c a l l y (F= 4 2 . 7 4 , F o r a l l groups t h e c o n c e n t r i c  than e c c e n t r i c r a t i o s ( X Q Q N " 5 3 . 7 ,  X£QQ=  r a t i o s were lower 57.7).  There were 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 t h r e e angular v e l o c i t i e s (F= 4 . 5 2 , p< 0 . 0 2 ) when averaged over the t h r e e groups o f s u b j e c t s ^135"  55,5,  and two c o n t r a c t i o n types  ^iQQ= 5 6 . 3 ) . F u r t h e r  Scheffé's a n a l y s i s  (XgQ= 5 5 . 3 , indicated  t h a t r a t i o s produced at 1 8 0 deg/sec"-'- were s i g n i f i c a n t l y greater  (p< 0 . 0 5 ) than those produced f o r e i t h e r 9 0 or 1 3 5  deg/sec"-^ w h i l e those produced f o r 9 0 and 1 3 5 deg/sec"-'- were not  significantly different Significant  a t h l e t i c group  (p> 0 . 0 5 ) .  interactions  i n c l u d e d a c o n t r a c t i o n type X  (F= 4 . 1 8 , p< 0 . 0 3 ) and a c o n t r a c t i o n type X  angular v e l o c i t y  (F= 4 . 6 9 , p< 0 . 0 2 ) while t h e a t h l e t i c group X  angular v e l o c i t y  and t h e a t h l e t i c group X c o n t r a c t i o n type X  angular v e l o c i t y  interactions  were not s i g n i f i c a n t .  When  averaged over t h e t h r e e angular v e l o c i t i e s t h e d i f f e r e n c e s between c o n c e n t r i c and e c c e n t r i c the  t h r e e groups o f s u b j e c t s .  produced s i m i l a r the as  r a t i o s were d i f f e r e n t among  While the ATR and MA groups  r a t i o s both 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 ,  P A group r a t i o ' s were s i g n i f i c a n t l y g r e a t e r compared t o t h e i r c o n c e n t r i c r a t i o s  ATR= 5 1 . 5 , 52.7)  eccentrically  (XQQN-PA^ 5 9 . 9 ,  XQQjj_f^= 4 9 . 7 / XgQQ_p;^=66.7, ^ECC-ATK^ as d i s p l a y e d i n F i g u r e 4 . 1 0 .  "XQQJ^.  54.1,  X^QQ_  Post hoc a n a l y s i s  r e v e a l e d t h a t XgQQ_pj^ was s i g n i f i c a n t l y g r e a t e r than Xg^Q.^ipj^ and  XgQ(-<_j^ a t p< 0 . 0 1 , while ^con-FA  than XcoN-ATR The  ^CON-MA  s i g n i f i c a n t l y greater  p< 0 . 0 1 .  s i g n i f i c a n t c o n t r a c t i o n type X angular  interaction  indicates  t h a t when averaged over t h e t h r e e sub-  j e c t groups t h e d i f f e r e n c e concentrically  velocity  i n the r a t i o s t h a t were produced  and e c c e n t r i c a l l y were s i g n i f i c a n t l y d i f f e r e n t  between the t h r e e angular v e l o c i t i e s .  As seen i n F i g u r e 4 . 1 1 ,  as t h e speed o f c o n t r a c t i o n i n c r e a s e d c o n c e n t r i c increased while e c c e n t r i c 52.7,  XQON135'" 5 3 . 6 ,  57.3,  XgQQ^BO" 5 7 . 9 ) .  ratios  r a t i o s remained unchanged (X^oN90'^  XQQJJ^^sO"" ^^'"^ ^ ^ E C C 9 0 "  57.9,  Xg(-.c;|^35=  P a i r w i s e comparison r e v e a l e d t h a t XÇ-QJ^^Q  was  s i g n i f i c a n t l y g r e a t e r than XQQJJ^^QQ while X(~.QJ^J^35 was  nificantly  g r e a t e r than X^QJ^-^QQ at the p<  0.01  level.  sig-  TABLE 4.6 KF-E Ratios  Athletic Group & Contraction Type PA  ATR  MA  Ang.Velocity (deg/sec-1)  Mean  SD  CON  90 135 180  59.6 60.2 59.8  5.25 4.51 5.22  ECC  90 135 180  66.7 65.7 66.6  3.71 4.23 4.28  CON  90 135 180  50.8 51.1 52.6  7.21 6.19 9.45  ECC  90 135 180  54.4 53.4 54.4  7.10 6.53 6.73  CON  90 135 180  47.8 49.5 51.7  6.14 5.82 6.07  ECC  90 135 180  52.6 52.8 52.7  5.38 5.24 5.85  * significant Athletic Group main effect (F=32.85, P< 0.001 ) * Significant Contraction Type main effect (F=:42.74, p< 0.001) * significant Angular Velocity main effect (F=4.52, p< 0.02)  FIGURE 4.9 KF-E Ratios  Ratio %(KF/KEx 100%) 68.0 -  C90  135  180  E90  135  180  PA  59.6  60.2  59.8  66.7  65.7  66.6  ATR  50.8  51.1  52.6  54.4  53.4  54.4  MA  47.8  49.5  51.7  52.6  52.8  52.7  Contraction and Velocity (deg/sec-1)  BB  PA  • •  ATR  EU  MA  FIGURE 4.10  Contraction Type x Athletic Group Interaction Ratio %(KF/KEx 100%) 68.0 66.0 64.0 62.0 60.0 58.0 56.0 54.0 52.0 50.0 48.0 46.0  ECCENTRIC  CONCENTRIC  PA  66.7  59.9  ATR  54.1  51.5  MA  52.7  49.7 Contraction Type PA  — ^ ATR  Averaged over velocity  MA  1  FIGURE 4.11  Contraction Type x Angular Velocity Interaction  60.0  Ratio %(KF/KEx 100%)  59.0 58.0 57.0 56.0 55.0 54.0 53.0 52.0  1  1  1  90  135  180  ECCENTRIC  57.9  57.3  57.9  CONCENTRIC  52.7  53.6  54.7  Velocity (deg/sec-1) ECCENTRIC  - t - CONCENTRIC  Averaged over the three groups  Correlations The  c o r r e l a t i o n matrix can be  hypothesized, the  c o r r e l a t i o n s between VO2  t o produce torque; both c o n c e n t r i c f l e x o r s and  -0.28  c o r r e l a t e d and  f o r CKF,  j - c r i t i c a l at o< 0.01,  -0.27  df=  KE CKE,  and  0.29  The  the  ability  f o r the  -0.24  f o r CKF,  0.02  were the  57 = 0.33  f o r EKE,  for  r=  -0.24  EKF;  c o r r e l a t i o n s between SMM  and  0.31  r= 0.02  f o r EKF;  the  for  j - c r i t i c a l at  for a l l correlations.  s i g n i f i c a n t , moderately p o s i t i v e c o r r e l a t i o n s between  f o r CKE,  0.68  f o r CKF,  suggests t h a t the g r e a t e r using  (kg)  e c c e n t r i c a l l y by  a b i l i t y to produce torque and v e r t i c a l jumping a b i l i t y  r= 0.44  knee  for a l l correlations.  KF when averaged over the t h r e e groups:  (AO.Ol, df=  the  eccentric,  torque as produced c o n c e n t r i c a l l y and and  and  nonsignificant:  f o r EKE,  57 = 0.33  Also nonsignificant and  and  max  As  extensors averaged over the three groups of sub-  j e c t s , are n e g a t i v e l y f o r CKE,  seen i n Table 4.7,  the p r o t o c o l  0.48  f o r EKE,  and  0.74  one's a b i l i t y to v e r t i c a l l y  as d e s c r i b e d  previously  the g r e a t e r  for  of EKF  jump torque a  person w i l l be able to generate u s i n g the methods as employed f o r t h i s study  ( j ^ c r i t i c a l at<?(0.01, df=  57 = 0.33).  TABLE 4.7  Correlation Matrix VER.JUMP VER.JUIVIP V 0 2 MAX  V02  MAK  SMM  CKE  CKF  EKE  EKF  1.00 -0.35  1.00  SMM  0.49  -0.41  1.00  CKE  0.44  -0.24  0.02  1.00  CKF  0.68  -0.28  0.29  0.57  1.00  EKE  0.48  -0.27  0.02  0.86  0.56  1.00  EKF  0.74  -0.24  0.31  0.69  0.88  0.71  1.00  DISCUSSION T h i s study was  unique  i n t h a t torque was  only f o r g r a v i t y b e f o r e KF-E  c o r r e c t e d not  r a t i o s were c a l c u l a t e d , but  c o r r e c t e d f o r the percent of an i n d i v i d u a l ' s body weight c o u l d be accounted  f o r by s k e l e t a l muscle mass.  was which  As such, the  r e s u l t s o b t a i n e d are d i f f e r e n t than what e a r l i e r r e s e a r c h has reported.  While p r e v i o u s s t u d i e s have used a m u l t i t u d e of t e s t  p r o t o c o l s , o n l y r e c e n t l y has work been performed analyzed the KE and KF a b i l i t y t o produce torque.  As w e l l ,  which has  isokinetic  eccentric  f o r t h i s study, average torque was  measured  i n s t e a d of the more o f t e n used measures of peak or angle s p e c i f i c torques.  Kramer & MacDermid  torque can occur at d i f f e r e n t  (1989) s t a t e d t h a t peak  j o i n t angles and i s thus  by angular v e l o c i t y and muscle a c t i o n .  affected  Average torque,  however, allows a more a p p r o p r i a t e assessment i f the a b i l i t y of a muscle t o produce performed  f o r c e i s of i n t e r e s t .  w i t h a t w o - f o l d purpose.  The  T h i s study  f i r s t was  both c o n c e n t r i c and e c c e n t r i c torques as produced  was  t o examine by the  f l e x o r s and extensors of the knee i n a manner which best s i m u l a t e d those muscle l e n g t h - t e n s i o n r e l a t i o n s h i p s d u r i n g running.  The  second purpose  of t h i s study was  examine the d i f f e r e n c e s i n a b i l i t y t o produce  i n an attempt  ences between them.  t o determine  to  torque between  power a t h l e t e s , a e r o b i c a l l y t r a i n e d runners, and a c t i v e persons  found  moderately  i f t h e r e are d i f f e r -  Group D i f f e r e n c e s Mentioned after vertical were measured. outperformed  p r e v i o u s l y , s u b j e c t s f o r t h i s study were  grouped  jumping a b i l i t y and maximal oxygen consumption As a n t i c i p a t e d , the PA group  significantly  t h e MA and ATR groups by 44.6% and 37.0% respec-  t i v e l y when v e r t i c a l  jumping a b i l i t y was a s s e s s e d w h i l e these  l a s t two groups d i d not s i g n i f i c a n t l y d i f f e r .  These r e s u l t s  correspond t o what p r e v i o u s s t u d i e s have r e p o r t e d f o r PA and ATR v e r t i c a l Vandewalle  jumping d i f f e r e n c e s  (Melichna e t a l . 198 9,  e t a l . 1987).  When maximal a e r o b i c c a p a c i t y was measured t h e ATR group s i g n i f i c a n t l y outperformed  the PA and MA groups.  two d i d not s i g n i f i c a n t l y d i f f e r .  These l a s t  F o r t h i s study, t h e mean  score f o r t h e ATR group was 64.4 ml/kg/min w h i l e Melichna e t al.  found VO2 max f o r t h e i r endurance s u b j e c t s t o be 68 and  C r i e l a a r d & P i r n a y (1981) r e p o r t e d 77.6 ml/kg/min f o r t h e i r subjects.  VO2 max recorded f o r our PA group was a l s o  lower  than what was r e p o r t e d by C r i e l a a r d & P i r n a y and Melichna e t al.  f o r t h e i r sprint/power a t h l e t e s .  They r e c o r d e d v a l u e s o f  60 and 59 ml/kg/min r e s p e c t i v e l y w h i l e t h e PA f o r t h i s  study  had a mean o f 51.1 ml/kg/min and t h e MA s u b j e c t s had a mean o f 49.1. Anthropometric  measurement o f s k e l e t a l muscle mass  r e v e a l e d h i g h e r adipose t i s s u e - f r e e mass f o r t h e s u b j e c t s o f t h i s study than what was r e p o r t e d by M a r t i n e t a l . (1990). M a r t i n e t a l . (1990) r e p o r t e d c a d a v e r i c d i s s e c t e d muscle masses  which ranged from 27.4% t o 4 9.1% o f the body mass i n o l d e r persons  (> 50 years) and i n s t u d i e s which c o r r e c t e d f o r adipose  t i s s u e these r e s u l t s ranged from 36.6% t o 59.4%.  They hypothe-  s i z e d t h a t a t h l e t e s who p a r t i c i p a t e d i n a c t i v i t i e s which r e q u i r e d s t r e n g t h would have r e s u l t s , as c a l c u l a t e d by t h e i r p r e d i c t i o n equation, which were g r e a t e r than what they r e p o r t e d . For t h i s study, PA were c a l c u l a t e d t o have a mean s k e l e t a l muscle mass o f 52.4 kg w h i l e the means f o r the ATR and MA groups were 42.6 kg and 47.2 kg.  When s k e l e t a l muscle mass was  d i v i d e d by t o t a l body weight, r e s u l t i n g i n the percentage o f body weight t h a t c o u l d be accounted f o r by s k e l e t a l muscle mass these r e s u l t s i n c r e a s e d t o 64.2, the PA, ATR,  60.3, and 58.6% f o r each o f  and MA groups.  M a r t i n et a l . (1990) r e p o r t e d t h a t d e s p i t e the l i m i t a t i o n s of having a cadaver sample, t h e i r proposed e q u a t i o n appears t o p r o v i d e the best estimate o f s k e l e t a l muscle mass t o date i n t h a t i t i s the only c a d a v e r - v a l i d a t e d equation and i t g i v e s v a l u e s which are c o n s i s t e n t with a l l known d i s s e c t i o n d a t a . The PA group o f s u b j e c t s were a b l e t o produce s i g n i f i c a n t l y g r e a t e r torque, both 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 , than e i t h e r the ATR or MA groups at a l l v e l o c i t i e s and f o r both muscle groups w h i l e t h e r e were no s i g n i f i c a n t  differences  between the ATR and MA groups f o r e i t h e r c o n t r a c t i o n or between the two groups o f muscle.  T h i s i s i n accordance w i t h p r e v i o u s  s t u d i e s which have examined the d i f f e r e n c e s i n t o r q u e product i o n between  s i m i l a r groups of s u b j e c t s .  formed s i g n i f i c a n t l y h i g h e r v e r t i c a l  The PA group p e r -  jumps than e i t h e r o f the  other two groups which, a c c o r d i n g t o the 1989 study t h a t was performed  by Melichna and a s s o c i a t e s , i n d i c a t e s t h a t t h e i r l e g  muscles have a predominantly  h i g h e r percentage  muscle f i b r e than the other groups.  o f Type I I  I t has been r e p o r t e d  ( C o s t i l l e t a l . 1976, Melichna e t a l . 1989, Thorstensson e t a l . 1976b, Thorstensson e t a l . 1977) t h a t h i g h l e v e l s o f Type I I muscle f i b r e s are found i n e l i t e  c a l i b r e a t h l e t e s who compete  i n s p r i n t i n g and jumping events and t h a t these muscles a r e capable o f p r o d u c i n g h i g h l e v e l s o f f o r c e at a l l angular velocities. Gregor et a l . (1979) found t h a t f o r t h e i r female s u b j e c t s the s p r i n t e r s were able t o produce  greater i s o k i n e t i c  concen-  t r i c torque than c o u l d the endurance group when the knee extens o r s were examined. it  Thorstensson e t a l . (1976b) r e p o r t e d t h a t  i s reasonable t o suggest t h a t a h i g h percentage  o f Type I I  muscle f i b r e i s one p r e r e q u i s i t e f o r performing f a s t c o n t r a c t i o n s w i t h a p p r e c i a b l e t e n s i o n outputs. and Olson & Swett colleagues  (197 6b)  Henneman e t a l . (1965)  (1966) p r o v i d e d a b a s i s f o r Thorstensson and statement  t a i n i n g predominantly  r e p o r t i n g t h a t motor u n i t s  con-  Type I I muscle f i b r e have l a r g e r axons,  h i g h e r conduction v e l o c i t i e s ,  and r e l a t i v e l y h i g h e r t h r e s h o l d s .  Thorstensson et a l . (1977) r e p o r t e d t h a t f o r t h e i r s u b j e c t s w i t h the lowest percentage  o f Type I I f i b r e  the lowest torque when angular v e l o c i t y was h i g h e s t . f o r e , the amount o f f o r c e which can be produced  study,  produced There-  during fast  c o n t r a c t i o n s i s i n f l u e n c e d by the amount o f Type I I f i b r e s i n muscle  (Thorstensson et a l . 1976a, Thorstensson e t a l . 1976b).  I t should thus be expected t h a t i n d i v i d u a l s who  are a n a e r o b i c -  a l l y t r a i n e d and of a h i g h l e v e l of s k i l l t o have g r e a t e r percentages  of Type II muscle f i b r e s i n t h e i r l e g muscles  a l l o w i n g them t o be a b l e t o produce v i d u a l s w i t h a l e s s e r percentage  g r e a t e r torque than  of Type II muscle f i b r e i n  t h e i r l e g muscles. As p r e v i o u s l y d i s c u s s e d i n the review,  (see s e c t i o n Muscle  f i b r e composition)  literature  the extent t o  which an i n d i v i d u a l i s endowed with Type I or I I muscle i s g e n e t i c a l l y determined.  indi-  With t r a i n i n g ,  o n l y the  s i z e o f muscle f i b r e s w i l l be enhanced w h i l e minimal the composition of muscle f i b r e w i l l  occur.  fibres  relative change t o  Individuals  t r a i n a e r o b i c a l l y w i l l have h y p e r t r o p h i e d Type I muscle  who fibres  w h i l e those t r a i n i n g a n a e r o b i c a l l y w i l l have Type II muscle f i b r e s which are e n l a r g e d although f o r e i t h e r a t h l e t e the percent composition of f i b r e type which g e n e t i c a l l y occurs i n t h e i r muscles w i l l not change s i g n i f i c a n t l y .  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 T h i s study f u r t h e r supports p r e v i o u s r e s e a r c h (Bennett & Stauber 1986, Ghena et a l . 1991,  Highgenboten e t a l . 1988,  Kramer & MacDermid 1989, Maclntyre & Wessel 1988, P o u l i n et a l . 1992, al.  T r e d i n n i c k & Duncan 1988, Westing  et a l . 1988, W o r r e l l et  1991) f i n d i n g t h a t e c c e n t r i c torque was  significantly  g r e a t e r than c o n c e n t r i c torque f o r each of the t h r e e groups of s u b j e c t s at a l l v e l o c i t i e s ,  and f o r both groups of muscles.  has been r e p o r t e d elsewhere  (Asmussen 1952,  Komi 1973a, Rodgers & Berger 1974)  It  Kaneko & Komi 1984,  t h a t e c c e n t r i c muscle  a c t i o n s are more e f f i c i e n t than c o n c e n t r i c muscle a c t i o n s , u s i n g l e s s oxygen than do c o n c e n t r i c c o n t r a c t i o n s of comparable muscle u n i t a c t i v i t y .  Stauber  (1989) a l s o s t a t e d t h a t  greater  p h y s i o l o g i c a l cost occurs d u r i n g c o n c e n t r i c c o n t r a c t i o n s  than  f o r work performed e c c e n t r i c a l l y , t h i s d i f f e r e n c e becoming g r e a t e r as v e l o c i t y of c o n t r a c t i o n i n c r e a s e s .  I t was  i n h i s review of e c c e n t r i c muscle a c t i o n s who  reported  t h e r e are two  that  mechanisms, which d u r i n g e c c e n t r i c work, reduce  energy expenditure these being: motor u n i t s  Stauber  ( i n c r e a s e d EMG)  and  1) a l t e r e d recruitment  2) decreased energy u t i l i z a t i o n  of a c t i v e muscles which develop t e n s i o n w h i l e being Asmussen  of  (1952) s t a t e d t h a t d u r i n g e c c e n t r i c  stretched.  contractions  fewer motor u n i t s are employed to produce a c o n t r a c t i o n than what i s r e q u i r e d f o r c o n c e n t r i c c o n t r a c t i o n s .  Thus, when a  muscle i s f u l l y a c t i v a t e d i t i s able t o produce more torque e c c e n t r i c a l l y than c o n c e n t r i c a l l y p r o v i d i n g s i m i l a r muscle length-tension  relationships exist.  Rodgers & Berger  (1974)  and Walmsley et a l . (1986) both c i t e d s e v e r a l r e f e r e n c e s also stated that greater  l e v e l s of t e n s i o n o c c u r r e d  eccentric-  a l l y than what occurs f o r e i t h e r i s o m e t r i c or c o n c e n t r i c t r a c t i o n s at the  same j o i n t angle.  Asmussen  (1952) and  (1973a) have f u r t h e r s t a t e d t h a t the d i f f e r e n c e i n the t o produce f o r c e between c o n c e n t r i c and i s v e l o c i t y dependent.  eccentric  I f v e l o c i t y of c o n t r a c t i o n  which  conKomi  ability  contractions increases  maximal e c c e n t r i c f o r c e w i l l a l s o i n c r e a s e w h i l e maximal conc e n t r i c f o r c e decreases.  Therefore,  the  f a s t e r muscle con-  t r a c t i o n occurs the g r e a t e r the d i f f e r e n c e between e c c e n t r i c  and  c o n c e n t r i c work w h i l e c o r r e s p o n d i n g muscle u n i t  (EMG) remains f a i r l y constant  activity  (Komi 1973b).  It was found f o r t h i s study, when averaged over the three groups o f s u b j e c t s , the average i s o k i n e t i c c o n c e n t r i c  torque  t h a t was produced s i g n i f i c a n t l y decreased f o r both t h e KE and KF  as angular v e l o c i t y i n c r e a s e d .  velocity  (F-V) r e s e a r c h  Hill's initial  force-  on i s o l a t e d animal muscle found t h a t  d u r i n g c o n c e n t r i c work the f o r c e which c o u l d be a p p l i e d t o move an o b j e c t decreased as speed o f c o n t r a c t i o n i n c r e a s e d .  This  would continue t o occur u n t i l a v e l o c i t y was reached where even an unloaded muscle c o u l d not shorten. opposite the  was t r u e ; with an i n c r e a s e  F o r e c c e n t r i c work the  i n the speed o f c o n t r a c t i o n  f o r c e which c o u l d be a p p l i e d a l s o i n c r e a s e d t o a c e r t a i n  p o i n t where i t would then l e v e l o f f . Many s t u d i e s examining F-V r e l a t i o n s h i p s have attempted t o compare t h e i r r e s u l t s t o those r e p o r t e d by H i l l .  Research  examining c o n c e n t r i c F-V r e l a t i o n s h i p s found t h a t as c o n t r a c t i o n v e l o c i t y i n c r e a s e d the f o r c e t h a t was produced decreased as found by H i l l  (Asmussen e t a l . 1965, F i l l y a w e t a l . 1986,  G i l l i a m e t a l . 1979, Holmes & A l d e r i n k et  1984, Komi 1973, Oberg  a l . 1986, Sanderson et a l . 1984, Smith e t a l . 1981, S t a f f o r d  & Granna 1984, Thorstensson et a l . 1977, Wyatt & Edwards 1981). It has been h y p o t h e s i z e d t h a t such a d e c l i n e c o u l d be due t o a decrease i n the amount o f time f o r motor f i b r e  recruitment  (Rodgers & Berger 1974), muscle f i b r e composition al.  ( P o u l i n et  1992, Thorstensson et a l . 1977), or muscle a c t i v i t y  (Thorstensson et a l . 1977).  Ghena et a l . (1991) a l s o  level  reported  t h a t others b e l i e v e gender may c o n c e n t r i c f o r c e with  p l a y a r o l e i n the r e d u c t i o n  i n c r e a s i n g angular  Studies which have a l s o analyzed s h i p s have r e p o r t e d mixed r e s u l t s .  of  velocity.  e c c e n t r i c F-V  That i s not  relation-  a l l have found  e c c e n t r i c torque t o i n c r e a s e as the v e l o c i t y of c o n t r a c t i o n increases. extensor Duncan  Walmsley et a l . (1986) found t h a t e c c e n t r i c w r i s t  torque s i g n i f i c a n t l y i n c r e a s e d while  Tredinnick &  (1988) found t h a t f o r males knee extensor  torque i n c r e a s e d very  slightly  eccentric  from 60 t o 180 deg/sec"-^.  W o r r e l l et a l . (1991) found i n c r e a s i n g knee extensor e c c e n t r i c torque w i t h  i n c r e a s i n g angular  s i t y a t h l e t e s from 60 t o 180 deg/sec"^.  and  flexor  v e l o c i t i e s i n univerWesting et a l . (1988)  r e p o r t e d t h a t when v o l u n t a r y maximal e c c e n t r i c c o n t r a c t i o n s the knee extensors  were measured i s o k i n e t i c a l l y at 30 through  270 deg/sec"-*- torque d i d not i n c r e a s i n g angular  s i g n i f i c a n t l y increase  with  v e l o c i t y while Westing et a l . (1990)  r e p o r t e d t h a t knee extensor  e c c e n t r i c torque d i d not  ably i n c r e a s e at t e s t v e l o c i t i e s of 60, 180, and  i n t h i s study d i d not d i f f e r s i g n i f i c a n t l y ,  again  appreci-  360 deg/sec"-'-.  E c c e n t r i c torque produced by the t h r e e groups o f  constant  of  remaining  subjects fairly  f o r both the KE and KF as v e l o c i t y of c o n t r a c t i o n  increased.  E l o r a n t a & Komi (1980) found e c c e n t r i c torque to be  g r e a t e r than c o n c e n t r i c torque i n the knee extensors males, however, no  of college  s i g n i f i c a n t d i f f e r e n c e s i n e c c e n t r i c torque  between v e l o c i t i e s were found.  Kramer & MacDermid  (1989)  r e p o r t e d t h a t f o r t h e i r female s u b j e c t s c o n c e n t r i c knee extensor torque s i g n i f i c a n t l y d e c l i n e d as angular  velocity  increased  w h i l e e c c e n t r i c torque showed only a 3-5% v a r i a n c e not  which d i d  s i g n i f i c a n t l y d i f f e r at v e l o c i t i e s between 45 and 180  deg/sec"-*-; i n c r e a s i n g very  s l i g h t l y , plateauing,  or  decreasing.  They f u r t h e r s t a t e d t h a t t h i s was i n agreement with s e v e r a l previous  s t u d i e s which examined both the knee and elbow.  Jorgensen  (1976), and Hanten & Ramberg  t h a t e c c e n t r i c torque i n c r e a s e d  (1988) both  reported  and then decreased f o r t h e i r  subjects. C o n f l i c t i n g F-V r e s u l t s were a l s o r e p o r t e d by Ghena e t a l . (1991) and P o u l i n e t a l . (1992).  P o u l i n e t a l . found e c c e n t r i c  torque t o decrease i n t h e i r younger male s u b j e c t s  from 90 t o  180 deg/sec"-'-, but i n c r e a s e d  subjects.  They r e p o r t e d  s e v e r a l other  f o r t h e i r o l d e r male  s t u d i e s which have a l s o found  c o n c e n t r i c peak torque t o decrease w h i l e e c c e n t r i c peak torque increased  s l i g h t l y or p l a t e a u e d .  Ghena and c o l l e a g u e s  (1991)  found no s i g n i f i c a n t d i f f e r e n c e s t o e x i s t i n t h e i r male subj e c t ' s a b i l i t y t o produce e c c e n t r i c torque f o r both the knee extensors and f l e x o r s at angular v e l o c i t i e s of 60 and 120 deg/sec"-'-. Westing e t a l . (1988) performed a study which examined e c c e n t r i c and c o n c e n t r i c F-V c h a r a c t e r i s t i c s o f male knee extensors. trically  They had s u b j e c t s perform maximal v o l u n t a r y ,  stimulated,  t r a c t i o n s during  elec-  and a combination o f both types o f con-  isometric, concentric,  and e c c e n t r i c a c t i o n s .  They a l s o r e p o r t e d t h a t e c c e n t r i c torque d i d not i n c r e a s e corresponding increases  i n angular v e l o c i t y .  I t was  with  reported  t h a t a combination of e l e c t r i c a l s t i m u l a t i o n and maximal v o l -  untary c o n t r a c t i o n produced the g r e a t e s t f o r c e recorded the F-V model.  amount o f f o r c e while  d u r i n g e l e c t r i c s t i m u l a t i o n alone best The lowest f o r c e recorded  occurred  resembled  when maximal  voluntary  c o n t r a c t i o n s were measured without accompanying  ulation.  They suggested t h a t the f a i l u r e f o r e c c e n t r i c torque  to s i g n i f i c a n t l y increase with increases  stim-  i n angular v e l o c i t y  c o u l d be due t o a n e u r a l mechanism becoming a c t i v e d u r i n g maximal c o n t r a c t i o n s o f i n s i t u muscle which r e s t r i c t s t h e muscle's a b i l i t y t o produce maximal t e n s i o n .  They  reported  t h a t such a t e n s i o n - r e s t r i c t i n g mechanism has been suggested t o m a i n t a i n a " s a f e " maximal l e v e l o f t e n s i o n d u r i n g  i s o m e t r i c and  low v e l o c i t y c o n t r a c t i o n s . In a 1990 study by Westing e t a l . , they h y p o t h e s i z e d t h a t e l e c t r i c a l s t i m u l a t i o n o f a muscle would be s i m i l a r t o t h e p r o posed F-V s t u d i e s performed on i s o l a t e d animal muscle.  This  would e x p l a i n why t h e e l e c t r i c a l s t i m u l a t i o n c o n t r a c t i o n they measured i n t h e i r s u b j e c t s t h e i r 1988 study.  resembled the o r i g i n a l F-V curve i n  By performing such a c o n t r a c t i o n many n e u r a l  i n t e r a c t i o n s at t h e s p i n a l l e v e l are bypassed.  Once  r e s u l t s s i m i l a r t o t h e i r e a r l i e r study were obtained. concluded t h a t i t i s indeed p o s s i b l e t h a t n e u r a l c o u l d be p a r t i a l l y r e s p o n s i b l e  f o r causing  again They  inhibition  the f l a t t e n i n g of  the e c c e n t r i c torque curve d u r i n g maximal v o l u n t a r y  contrac-  t i o n , t h a t i s e c c e n t r i c torque not i n c r e a s i n g w i t h i n c r e a s i n g velocity. recorded  Stauber  (1989) a l s o mentioned t h a t e c c e n t r i c f o r c e  f o r i n s i t u t e s t i n g i s lower than an i s o l a t e d muscle  stimulated  e l e c t r i c a l l y thus a n e u r a l mechanism must be present  which h e l p s t o p r o t e c t muscle from Other  injury.  f a c t o r s which have been mentioned as p o s s i b l y being  r e l a t e d t o e c c e n t r i c torque not i n c r e a s i n g w i t h  corresponding  i n c r e a s e s i n angular v e l o c i t y i n c l u d e s u b j e c t p o s i t i o n i n g d u r i n g data c o l l e c t i o n .  P r e v i o u s work has almost  exclusively  examined torque measurements w i t h s u b j e c t s i n e i t h e r a s i t t i n g or  s e m i - r e c l i n e d p o s i t i o n f o r t e s t i n g of both the knee exten-  sors and f l e x o r s et  a l . 1989).  (Bohannon et a l . 1986,  C u r r i e r 1977,  Worrell  For t h i s study s u b j e c t s were examined w i t h a h i p  angle of 10° i n a prone  (KF) or supine  not allowed t o grasp any hand r a i l s Another h y p o t h e s i s as t o why with the e c c e n t r i c F-V  (KE) p o s i t i o n and were  for further  support.  t h e r e has been a c o n f l i c t  r e l a t i o n s h i p i s a l a c k of s u b j e c t f a m i l -  i a r i t y w i t h e c c e n t r i c c o n t r a c t i o n s which are produced test conditions.  under  S e v e r a l s t u d i e s , i n c l u d i n g the p r e s e n t  one,  have r e p o r t e d t h a t they c o l l e c t e d data w i t h the only form of f a m i l i a r i z a t i o n c o n s i s t i n g of p r e - t e s t r e p e t i t i o n s which were performed  immediately  p r i o r t o data c o l l e c t i o n .  t h i s study commented t h a t performing t h i s c o n t r a c t i o n was  Subjects for  computer-controlled  the most d i f f i c u l t p o r t i o n of the  study.  S e v e r a l needed e x t r a p r a c t i c e t r i a l s b e f o r e they were comfort a b l e w i t h t h i s s e c t i o n of the t e s t . performed  I f a p r a c t i c e s e s s i o n was  l e s s than a week p r i o r t o data c o l l e c t i o n then sub-  j e c t f a m i l i a r i t y with producing c o n t r o l l e d e c c e n t r i c c o n t r a c t i o n s on an i s o k i n e t i c dynamometer might r e s u l t i n b e t t e r s i m i l a r i t y t o the f o r c e - v e l o c i t y  curve.  Walmsley et a l . (1986) have suggested t h a t a f a i l u r e f o r  eccentric  torque t o i n c r e a s e with i n c r e a s i n g  angular v e l o c i t y  i s perhaps due t o d i f f e r e n t t e s t v e l o c i t i e s and/or d i f f e r e n t muscle groups t e s t e d . Kramer & MacDermid  However, Hinson  (1976), as r e p o r t e d by  (198 9) suggested t h a t  during i s o k i n e t i c i n  s i t u t e s t i n g t h e j o i n t ' s angular v e l o c i t y i s constant but the l i n e a r v e l o c i t y o f t h e muscle a c t i o n  i s not.  Therefore,  only  g e n e r a l comparisons should be made between human i s o k i n e t i c t e s t i n g and t h e F-V r e l a t i o n s h i p because c l i n i c a l responses t o changes i n angular v e l o c i t y a r e more important than comparison t o t h e c l a s s i c model. F i n a l l y , Chapman (1985) r e p o r t e d t h a t  although t h e F-V  r e l a t i o n s h i p as proposed by H i l l has not been v e r i f i e d as being universally  applicable  f o r a l l muscle groups w i t h i n  body, t h e r e i s evidence which suggests t h a t V relationship,  stated  some form o f the F-  t h e r e s u l t o f a combination o f separate  s i c F-V r e l a t i o n s h i p s further  t h e human  that  within  intrin-  t h e muscle group, does e x i s t .  t h e F-V r e l a t i o n s h i p  He  can never be t r u l y  viewed as fundamental s i n c e many o f t h e c o n d i t i o n s under which it  i s tested  a p p a r e n t l y modify the r e l a t i o n s h i p which  force  length relationships,  state  o f muscle c o n t r a c t i o n ,  types have i n muscular  l e v e l o f muscle a c t i v a t i o n , and t h e r o l e t h a t  include prior  different fibre  contraction.  Knee Extensor and F l e x o r Torque As hypothesized, t h e knee extensors o f a l l t h r e e s u b j e c t groups produced s i g n i f i c a n t l y g r e a t e r c o n c e n t r i c  and e c c e n t r i c  torque than t h e knee f l e x o r s at each t e s t v e l o c i t y examined.  T h e s e r e s u l t s a r e s u p p o r t e d by t h e p a s t f i n d i n g s o f Ghena e t al.  (1991), H a r d i n g e t a l . (1988), Highgenboten  (1988), K l o p f e r & G r e i j e t a l . (1984), and s t a t e d t h a t one  (1988), P i e t e r e t a l . (1989),  Smith e t a l . (1981).  s h o u l d e x p e c t KE t o r q u e t o be g r e a t e r t h a n  s t u d y , h o w e v e r , has  t h e KF e x c e e d e d was  performed  deg/sec"-'-  Klopfer & Greij,  by  whose s t u d y  concentrically using angular v e l o c i t i e s  a n d g r e a t e r on t h e B i o d e x B-2000 i s o k i n e t i c  of  300  dyna-  f o r t h e i r u n t r a i n e d female s u b j e c t s ,  greater than that  f o r t h e KE  They f o u n d t h a t KF t o r q u e a c t u a l l y angular  KF  mass.  r e p o r t e d t h a t torque produced  t h a t o f t h e KE.  mometer, r e p o r t e d t h a t t o r q u e was  Sanderson  P i e t e r e t a l . (1989)  t o r q u e c o n s i d e r i n g i t has a l a r g e r m u s c l e One  and c o l l e a g u e s  at each t e s t  increased with  KF  velocity.  increasing  velocities.  S e v e r a l s u g g e s t i o n s w e r e o f f e r e d as t o why  this  occurred  i n c l u d i n g t h a t d u r i n g the e x t e n s i o n phase o f e x e r c i s e t h e r e i s an i n c r e a s e i n KF a c t i v i t y w h i c h o c c u r s as t h e r e s u l t  of  an  attempt t o slow the lower l e g d u r i n g the e x t e n s i o n phase of exercise  (See l i t e r a t u r e r e v i e w : Analysis  of Running  K l o p f e r & G r e i j h y p o t h e s i z e d t h a t i f t h e knee f l e x o r s composed p r e d o m i n a n t l y o f Type I I m u s c l e  be e x p e c t e d .  with increase  C o n v e r s e l y , i f knee e x t e n s o r s  w e r e p r e d o m i n a n t l y c o m p r i s e d o f Type I f i b r e s t h e n a i n t o r q u e p r o d u c t i o n w i t h an i n c r e a s e i n v e l o c i t y may expected which (1977) .  were  f i b r e t h e n an i n c r e a s e  i n t h e amount o f t o r q u e w h i c h c o u l d be p r o d u c e d i n v e l o c i t y may  Motion).  decrease be  i s s u p p o r t e d by t h e w o r k o f T h o r s t e n s s o n e t a l .  T h i s i s a very unique f i n d i n g i n t h a t i t i s the only  study  t o r e p o r t torque produced by the KF t o exceed t h a t capable by the KE.  One  result  i s the  other p o s s i b l e f a c t o r which might e x p l a i n fact that t h e i r untrained  formed c o n c e n t r i c c o n t r a c t i o n s which are not  female s u b j e c t s  at v e l o c i t i e s of  commonly examined.  this per-  contraction  As w e l l , remembering  the  statement by Ghena et a l . ( 1 9 9 0 ) , i t i s b e l i e v e d t h a t t h e r e i s a gender d i f f e r e n c e i n the r a t e at which c o n c e n t r i c decreases as the v e l o c i t y of c o n t r a c t i o n The  torque  increases.  r e s u l t s which were measured f o r the KE of a l l t h r e e  groups were higher  than a n t i c i p a t e d c o n s i d e r i n g the  p o s i t i o n which was  used.  As mentioned p r e v i o u s l y ,  supine t e s t several  s t u d i e s have examined the d i f f e r e n c e s i n the a b i l i t y t o produce torque from seated,  semi-reclined,  and/or supine p o s i t i o n s .  W o r r e l l et a l . (1989) r e p o r t e d t h a t torque produced by the knee extensors i n a seated p o s i t i o n (80° of h i p f l e x i o n ) was i c a n t l y g r e a t e r than what was position  (10° h i p f l e x i o n ) .  s t a t e d t h a t the optimal rectus Any  recorded  from a supine t e s t  W o r r e l l et a l . (1989)  length-tension  further  r e l a t i o n s h i p of  femoris muscle occurs between 50 and  80° of h i p  p o s i t i o n l e s s than 50° or g r e a t e r than 90° does not  an optimal  signif-  the flexion. provide  r e l a t i o n s h i p and w i l l thus r e s u l t i n a decrease i n  the amount o f torque which i s produced. Currier seated  and  (1977) r e p o r t e d  s i g n i f i c a n t d i f f e r e n c e s between a  s e m i - r e c l i n e d p o s i t i o n , however, Bohannon et a l .  (1986) d i d not.  Bohannon and  colleagues  found t h a t no  signif-  l e a n t d i f f e r e n c e s e x i s t e d i n t h e torque produced from p o s i t i o n s of 30 and 80° o f h i p f l e x i o n f o r the KE.  They r e p o r t e d t h a t  p o s s i b l e d i f f e r e n c e s between t h e i r study and t h a t performed by C u r r i e r were due t o d i f f e r e n t s u b j e c t s t a b i l i z a t i o n T h e i r s u b j e c t s were not p e r m i t t e d t o grasp handles  techniques. while  C u r r i e r ' s s u b j e c t s were allowed t h i s method o f s t a b i l i z a t i o n . For the present torque  study,  s u b j e c t s were examined f o r KE  i n a supine p o s i t i o n o f 10° h i p f l e x i o n , not the optimal  l e n g t h - t e n s i o n r e l a t i o n s h i p as suggested by W o r r e l l e t a l . (1989), and were not p e r m i t t e d  t o grasp the handles.  However,  i n s t e a d o f u s i n g an a r b i t r a r y p r e - l o a d f o r c e o f 25 or 50N as some s t u d i e s have done (Bennett  & Stauber 1986, Hageman e t a l .  1988, T r e d i n n i c k & Duncan 1988, W o r r e l l e t a l . 1990, W o r r e l l e t al.  1991), 75% o f a s u b j e c t ' s MVIC was used t o determine the  pre-load force l e v e l .  Jensen e t a l . (1991) r e p o r t e d t h a t a 75%  MVIC p r e - l o a d helped t o reduce any a f f e c t t h a t p o s i t i v e o r negative  a c c e l e r a t i o n may have had i n i n f l u e n c i n g torque.  F u r t h e r r e f e r e n c e t o Jensen and c o l l e a g u e s work can be l o c a t e d i n the "Faults  with  ature review.  The author b e l i e v e s t h a t the h i g h e r than  pated  previous  research"  r e s u l t s f o r the knee extensors  section of the l i t e r antici-  may be accounted f o r due  t o t h e use o f t h i s high l e v e l o f p r e - l o a d as w e l l as t h e d i f f e r e n t methods o f s t a b i l i z a t i o n . S e v e r a l authors  have r e p o r t e d t h a t as the v e l o c i t y o f con-  t r a c t i o n i n c r e a s e s the amount o f torque  t h a t can be produced  c o n c e n t r i c a l l y decreases at a much f a s t e r r a t e f o r the KE than f o r the KF (Ghena e t a l . 1991, Hageman e t a l . 1988, Holmes &  Alderink  1984, K l o p f e r  & G r e i j 1988, Oberg e t a l . 1986,  S t a f f o r d & Granna 1984) . The  r e s u l t s o f t h i s study support e a r l i e r r e s e a r c h  f i n d i n g that during at a g r e a t e r  concentric  contractions  also  KE torque decreases  r a t e than does KF w i t h i n c r e a s i n g angular v e l o c i -  t y , however KF torque d i d not exceed KE t o r q u e .  When the r a t e  of d e c l i n e between angular v e l o c i t i e s was examined i t was found t h a t MA and PA groups demonstrated s i m i l a r l e v e l s o f d e c l i n e w i t h i n c r e a s i n g angular v e l o c i t y when c o n c e n t r i c  torque was  measured f o r the KE w h i l e the ATR group had t h e l e a s t amount o f decline.  When a n a l y z i n g  the d i f f e r e n c e s between 90 t o 135  deg/sec"-^ the MA group o f s u b j e c t s d e c l i n e i n KE c o n c e n t r i c ATR 0.16  torque:  demonstrated t h e g r e a t e s t 0.20 Nm/kg c o r r . , while the  and PA groups r a t e o f d e c l i n e was measured t o be 0.17 and Nm/kg c o r r . r e s p e c t i v e l y .  When d i f f e r e n c e s i n KE torque  were analyzed between t h e t e s t v e l o c i t i e s o f 135 and 180 deg/sec"-^ the PA group demonstrated the g r e a t e s t decline only  rate of  (0.26 Nm/kg c o r r . ) while t h e MA and ATR groups d e c l i n e d  0.22 and 0.19 Nm/kg c o r r . r e s p e c t i v e l y . As  f o r the r a t e o f d e c l i n e when KF torque was  evaluated  between t h e angular v e l o c i t i e s o f 90 and 135 deg/sec"-*- t h e ATR group showed only a s l i g h t l y g r e a t e r than d i d t h e PA group  rate  (0.09 Nm/kg c o r r . )  (0.08 Nm/kg c o r r . ) w h i l e t h e MA group  only decreased 0.05 Nm/kg c o r r . .  Decline  i n t h e measured con-  c e n t r i c KF torque between 135 and 180 deg/sec"-*- was g r e a t e s t f o r t h e PA a t 0.17 Nm/kg c o r r . w h i l e the ATR and MA groups demonstrated  a d e c l i n e o f 0.1 and 0.08 Nm/kg c o r r . r e s p e c t i v e l y .  Garrett  (1983) r e p o r t e d t h a t the KF are known t o have  r e l a t i v e l y h i g h l e v e l s o f Type I I muscle f i b r e and are i n v o l v e d i n intense contractions.  Polgar  the composition o f percent  e t a l . (1973), who examined  muscle f i b r e i n s e v e r a l  different  muscles, a l s o s t a t e d t h a t the KF have a h i g h percentage o f Type II f i b r e and f u r t h e r suggested t h a t these muscles a r e more i n v o l v e d w i t h e x e r c i s e o f high i n t e n s i t y Thus i f t h e KF have higher  and f o r c e  production.  l e v e l s o f Type I I muscle f i b r e than  the KE they are more capable o f p r o d u c i n g g r e a t e r torque a t h i g h v e l o c i t i e s o f c o n t r a c t i o n as compared t o the KE. Thorstensson et a l . (1976b) r e p o r t e d t h a t motor u n i t s which recorded  higher  t e n s i o n outputs and s h o r t e r c o n t r a c t i o n times  were shown t o c o n t a i n a g r e a t e r percentage o f Type I I f i b r e as compared t o Type I muscle f i b r e i n t h e i r  subjects.  With t h i s knowledge t h a t d u r i n g c o n c e n t r i c torque produced by the KE decreases at a g r e a t e r the KF f u r t h e r e x p l a n a t i o n Greij  (1988) can occur.  particular velocity  o f the r e s u l t s  I t i s conceivable  group o f u n t r a i n e d  contractions r a t e than f o r  r e p o r t e d by K l o p f e r & that f o r t h e i r  females, b e g i n n i n g a t t h e angular  o f 300 deg/sec"-'- t h e r e  i s a change i n which group o f  muscles can produce the g r e a t e s t torque; from KE t o KF, thus e x p l a i n i n g why recorded t h a t produced by the KE.  c o n c e n t r i c KF torque was g r e a t e r  than  KF-E R a t i o s S i g n i f i c a n t l y g r e a t e r c o n c e n t r i c and e c c e n t r i c KF-E r a t i o s were found t o e x i s t between the PA group and both the MA and ATR groups o f s u b j e c t s w h i l e t h e r a t i o s produced by these two groups were not s i g n i f i c a n t l y d i f f e r e n t  last  from each o t h e r .  The author suggests t h a t h i g h e r KF-E r a t i o s may be r e q u i r e d by PA a t h l e t e s t o compete s u c c e s s f u l l y as w e l l as t o prevent injury. U n f o r t u n a t e l y much o f the p r e v i o u s r e s e a r c h which examined KF-E  r a t i o s has f a i l e d t o c o r r e c t f o r g r a v i t y .  This error  r e s u l t s i n an i n f l a t e d r a t i o as r e p o r t e d by F i l l y a w e t a l . (1986) and Sanderson  e t a l . (1984) when both the knee f l e x o r s  and extensors are examined i n a supine p o s i t i o n .  Thus, uncor-  r e c t e d s t u d i e s can not be used t o develop standards which a i d the a t h l e t e , coach, and/or p h y s i o t h e r a p i s t s i n d e t e r m i n i n g i f an i n d i v i d u a l i s capable o f w i t h s t a n d i n g those f o r c e s  specific  t o t h e i r a c t i v i t y or i f they are at r i s k f o r f u t u r e p o s s i b l e injury. E ratios,  The present study performed was unique i n t h a t t h e KFl i k e measured c o n c e n t r i c and e c c e n t r i c torque, were  not c a l c u l a t e d u s i n g s o l e l y the torque v a l u e s measured or torque c o r r e c t e d f o r i n d i v i d u a l body weight, but was c o r r e c t e d f o r t h e percent o f an i n d i v i d u a l ' s body weight which c o u l d be accounted f o r by s k e l e t a l muscle mass. For each o f the t h r e e groups o f s u b j e c t s i n t h i s study the c o n c e n t r i c KF-E r a t i o s were s i g n i f i c a n t l y lower than those calculated f o r eccentric contractions.  T h i s was e s p e c i a l l y  s e e n i n t h e PA g r o u p w h e r e t h e d i f f e r e n c e b e t w e e n  concentric  a n d e c c e n t r i c KF-E r a t i o s was on a v e r a g e 6% w h i l e d i f f e r e n c e s f o r e a c h o f t h e o t h e r two g r o u p s was b e t w e e n  1 a n d 5%.  It is  s u g g e s t e d by t h e a u t h o r t h a t b e c a u s e power a t h l e t e s a r e r e q u i red t o perform at high v e l o c i t i e s  o f movement a n d a r e a t t i m e s  r e q u i r e d t o p e r f o r m so t h a t h i g h e x t r i n s i c  loads are placed  u p o n t h e m l a r g e e c c e n t r i c KF-E r a t i o s a r e r e q u i r e d t o a d e q u a t e l y p e r f o r m a n d do s o w i t h o u t i n j u r y . Such f i n d i n g s have been r e p o r t e d e l s e w h e r e 1991, H i g h g e n b o t e n e t a l . 1 9 8 8 ) .  (Ghena e t a l .  H i g h g e n b o t e n e t a l . (1988)  r e p o r t e d c o n c e n t r i c r a t i o s o f 54% f o r t h e i r u n t r a i n e d males  young  (15-24 y e a r s ) , 5 1 % f o r t h e i r o l d e r m a l e s u b j e c t s  (25-34  y e a r s ) a n d e c c e n t r i c r a t i o s o f 6 0 % f o r b o t h g r o u p s when examined  a t 50 deg/sec"-*-.  Ghena e t a l . (1991)  found e c c e n t r i c  r a t i o s o f 6 4 . 6 % a n d 6 5 . 0 % a t 60 a n d 120 deg/sec"-*- r e s p e c t i v e l y w h i l e c o n c e n t r i c r a t i o s w e r e 5 5 . 3 , 57.7 a t 60 a n d 120 deg/sec"•*• i n c r e a s i n g t o 60.9 a n d 8 0 . 4 % a t t e s t v e l o c i t i e s deg/sec"-*- f o r t h e i r  o f 300, a n d 450  s u b j e c t s who w e r e m a l e u n i v e r s i t y a t h l e t e s  competing i n a v a r i e t y o f s p o r t s .  Unfortunately  t h e y were n o t  a b l e t o measure e c c e n t r i c r a t i o s a t a n g u l a r v e l o c i t i e s t h a n 120 deg/sec"-*- due t o e q u i p m e n t  greater  restrictions.  One f i n d i n g w h i c h h a s b e e n common t o n e a r l y e v e r y s t u d y e x a m i n i n g KF-E r a t i o s  i s f o r c o n c e n t r i c r a t i o s t o i n c r e a s e as  the v e l o c i t y at which they are c a l c u l a t e d f o r increases  (Ghena  e t a l . 1 9 9 1 , K l o p f e r & G r e i j 1988, S a n d e r s o n e t a l . 1 9 8 4 ) . T h i s r i s i n g c o n c e n t r i c t o r q u e r a t i o c a n be e x p l a i n e d b y p a s t f i n d i n g s w h i c h r e p o r t e d t h a t KE t o r q u e d e c l i n e s a t a more r a p i d  r a t e than KF torque  during concentric c o n t r a c t i o n s .  t h e r e i s l e s s of a d i f f e r e n c e between the two  Thus,  muscle groups as  v e l o c i t y i n c r e a s e s and the c a l c u l a t e d r a t i o w i l l be than at a l e s s e r angular v e l o c i t y .  I t would be of great  i n t e r e s t t o t h i s f i e l d of r e s e a r c h i f a study was which examined the hamstring MSI  The support  i f so how  t h i s might  MSI.  r e s u l t s of the c o n c e n t r i c KF-E the p r e v i o u s  performed  a t h l e t e p o p u l a t i o n t o see i f  they demonstrated a h i g h e r d i f f e r e n c e and be a s s o c i a t e d with hamstring  greater  ratios,  r e s e a r c h which found KF-E  as angular v e l o c i t y i n c r e a s e d f o r both the MA  for this r a t i o s to  and ATR  study, rise  groups,  however, the PA group's c o n c e n t r i c r a t i o s remained r e l a t i v e l y unchanged.  T h i s would suggest t h a t , f o r the PA group,  amount of d e c l i n e i n c o n c e n t r i c torque p r o d u c t i o n KE and KF was  approximately  similar.  the  f o r both the  T h i s i s l o g i c a l because  e l i t e s p r i n t a t h l e t e s have been shown t o have h i g h e r l e v e l s Type II muscle f i b r e i n a l l l e g muscles as r e p o r t e d Thorstensson  et a l . (1977).  Only two  fering velocities.  s i m i l a r percentages  s t u d i e s t o date have r e p o r t e d  gravity corrected eccentric ratios Highgenboten et a l . 1988)  (Ghena et a l .  1991,  and u n f o r t u n a t e l y only one  Ghena et a l . (1991) found a very  i n c r e a s e i n the e c c e n t r i c r a t i o produced f o r t h e i r u s i n g v e l o c i t i e s o f 60 and The  by  It i s therefore possible that for  t h i s group o f s u b j e c t s , the KE and KF had o f Type II f i b r e s .  e c c e n t r i c KF-E  of  120  at  dif-  small  subjects  deg/sec"-*-.  r a t i o s remained steady  across  angular  v e l o c i t i e s f o r each of the three groups i n t h i s study  because  e c c e n t r i c torque f o r each group's KE and KF d i d not d i f f e r as v e l o c i t y i n c r e a s e d , c o n f l i c t i n g w i t h the f o r c e - v e l o c i t y tionship.  rela-  A r i s e i n the e c c e n t r i c KF-E r a t i o as angular  v e l o c i t y i n c r e a s e d would r e q u i r e torque produced by the knee f l e x o r s t o i n c r e a s e at a g r e a t e r r a t e than f o r t h e knee extensors.  Stanton & Purdam  (1989) f e l t t h a t s p r i n t e r s which sus-  t a i n e d hamstring MSI had lower knee f l e x o r e c c e n t r i c torque e s p e c i a l l y at h i g h e r angular v e l o c i t i e s .  Thus t h i s may be an  area where persons prone t o hamstring MSI are d e f i c i e n t or d i s p l a y a degree o f asymmetry. Both t h e c o n c e n t r i c and e c c e n t r i c r a t i o s found f o r t h i s study a r e q u i t e s i m i l a r t o those r e p o r t e d by Ghena e t a l . (1991) when the power and endurance groups gether as was the case f o r t h e i r study.  are averaged t o -  The MA KF-E r a t i o s  c a l c u l a t e d f o r t h i s study were s l i g h t l y h i g h e r than those r e p o r t e d by Sanderson jects:  e t a l . (1984) f o r t h e i r sedentary  sub-  c o n c e n t r i c KF-E r a t i o s f o r males t o be 44 and 4 8 % at  t e s t v e l o c i t i e s o f 60 and 180 deg/sec"-*- r e s p e c t i v e l y w h i l e their  female s u b j e c t s had r a t i o s o f 39 and 4 2 % r e s p e c t i v e l y at  the same v e l o c i t i e s .  The moderately  a c t i v e r e s u l t s were,  however, much lower than what K l o p f e r & G r e i j f o r both t h e i r male and female s u b j e c t s .  (1988) r e p o r t e d  Klopfer & Greij  c a l c u l a t e d u n t r a i n e d males KF-E r a t i o s at angular v e l o c i t i e s o f 300, 3 3 0 , 3 6 0 , 4 0 0 , and 450 deg/sec"^.  They found t h a t these  c o n c e n t r i c r a t i o s were 7 2 . 9 , 8 4 . 1 , 82.8, 8 5 . 5 , and 9 7 . 1 % respectively.  F o r t h e i r u n t r a i n e d females r a t i o s o f 110, 1 0 8 ,  112, 114, and 1 0 8 % were found t o e x i s t at the same v e l o c i t i e s .  KF-E what was  ratios  a t b o t h v e l o c i t i e s w e r e f o u n d t o be s i m i l a r  r e c o r d e d f o r our endurance  l o w e r t h a n what was  found t o e x i s t  g r o u p , t h u s b e i n g much f o r our power  subjects.  H i g h g e n b o t e n e t a l . ( 1 9 8 8 ) , whose e c c e n t r i c r e s u l t s ted  earlier,  ely  7% h i g h e r when e x a m i n e d  MA  f o u n d e c c e n t r i c KF-E  g r o u p whose r a t i o s  to  were r e p o r -  r a t i o s w h i c h were a p p r o x i m a t -  a t 60 deg/sec"-*- as c o m p a r e d t o o u r  r a n g e d f r o m 52.6  t o 52.8  at v e l o c i t i e s  of  90-180 d e g / s e c " ^ . P r e v i o u s l i t e r a t u r e h a s s u g g e s t e d t h a t t h e KF-E measured al.  c a n be a f f e c t e d by age  1988), s k i l l  1984,  Rodgers  1989).  dependent  (Holmes  (Worrell et a l .  e t a l . (1979) p r o p o s e d t h a t e a c h i n d i v i d u a l  has  r a t i o w h i c h i s " i d e a l " f o r them  upon p h y s i c a l c h a r a c t e r i s t i c s ,  sport of  participation  position.  S i g n i f i c a n c e o f KF-E  Asymmetry  S e v e r a l s t u d i e s have a t t e m p t e d t o a s s o c i a t e h a m s t r i n g muscle s t r a i n i n j u r y al.  (1984)  and KF-E  &  (Komi & B u s k i r k  & B e r g e r 1974), and h i p p o s i t i o n  Gilliam  position  of c o n t r a c t i o n  W o r r e l l e t a l . 1989), gender  a s e p a r a t e a n d d i s t i n c t KF-E  and  (Oberg e t a l . 1 9 8 6 ) ,  ( G i l l i a m e t a l . 1979), v e l o c i t y  Alderink 1972,  (Ghena e t a l . 1991, W e l t m a n e t  l e v e l and r e s p e c t i v e t r a i n i n g w h i c h accomp-  anies a high l e v e l of s k i l l played  ratios  asymmetry/imbalance.  Heiser et  found t h a t i n c o l l e g e f o o t b a l l p l a y e r s a dramatic  reduction i n hamstring i n j u r i e s occurred following a d e s i g n e d p r o p h y l a c t i c r e h a b i l i t a t i o n program which  specially  increased  every p l a y e r ' s KF-E  r a t i o to at l e a s t 60%.  p r e d i c t i n g hamstring MSI  Burkett  (1970), i n  i n professional f o o t b a l l players  t r a c k a t h l e t e s , found t h a t an asymmetry of g r e a t e r than between the r i g h t and  l e f t knee f l e x o r s r e s u l t e d i n a  occurrence of hamstring MSI i n knee extensor and  and  and  10%  greater  further stated that a  reduction  f l e x o r s t r e n g t h d i f f e r e n c e s would be  u s e f u l i n the p r e v e n t i o n  of hamstring s t r a i n s .  In a l a r g e r , r e t r o s p e c t i v e study Knapik et a l . (1991) reported  t h a t lower extremity  i n j u r y was  more p r e v a l e n t  in  t h e i r female c o l l e g i a t e a t h l e t e s i f 1) a d i f f e r e n c e of 15% g r e a t e r e x i s t e d between the r i g h t and examined at 180  deg/sec"^ and  75% was  when c a l c u l a t e d at 180  All  present  of these s t u d i e s and  2)  left  i f a KF-E  others  knee f l e x o r s when r a t i o of l e s s than  deg/sec"-*-.  have r e p o r t e d d i f f e r e n t  KF-E  r a t i o s which should be maintained f o r i n j u r y  (See  l i t e r a t u r e review:  KF-E  Assessment).  agree on normative r a t i o s which should prevent i n j u r y perhaps KF-E  prevention  Because few  which examines not  (1984).  studies  e x i s t i n attempts t o  r a t i o s are indeed sport and/or  p o s i t i o n s p e c i f i c as suggested by G i l l i a m et a l . (1979) Holmes & A l d e r i n k  or  More r e s e a r c h  needs t o be  only the a s s o c i a t i o n between KF-E  and  performed muscle  asymmetry and hamstring muscle s t r a i n i n j u r y i n l a r g e r samples l i k e the Knapik et a l . study but asymmetry.  a l s o the e f f e c t of between l e g  T h i s work, however, needs t o be performed w i t h  consideration to simulating  length-tension  r e l a t i o n s h i p s spe-  c i f i c t o t h a t s p o r t i n which the measured KF-E associated with.  As w e l l , r e s e a r c h  r a t i o s are t o  should be performed t o  be  investigate period  i f KF-E r a t i o s can be changed w i t h t r a i n i n g over a  o f time.  To date no study has examined the e f f e c t s o f  t r a i n i n g on KF-E r a t i o s .  Goal o f R e h a b i l i t a t i o n Considering that  few v a l i d s t u d i e s have been performed  which i n v e s t i g a t e u n i n j u r e d  a t h l e t e s encompassing a v a r i e t y of  ages, weights, s p o r t s / p o s i t i o n s ,  and gender an a c c u r a t e  rela-  t i o n s h i p between KF-E r a t i o s and r e h a b i l i t a t i o n can not occur. As w e l l , c u r r e n t achieving  i s o k i n e t i c dynamometers are not capable o f  the angular v e l o c i t i e s which are present  a t h l e t i c competition.  during  Thus no one i s d e f i n i t e as t o how  i n d i v i d u a l s respond t o such v e l o c i t i e s under t e s t  conditions.  F u r t h e r i n v e s t i g a t i o n o f e c c e n t r i c knee e x t e n s o r and f l e x o r torque and t h e i r r a t i o s must be undertaken which examines d i f f e r e n t groups o f a t h l e t e s research  considering  the l a c k o f  which examines e c c e n t r i c muscle a c t i o n s .  and  concentric  research,  the  f o r c e s present d u r i n g  Eccentric  i f the r e s u l t s are t o be compared t o c o m p e t i t i o n such as the running  motion, need t o be performed i n a manner which c l o s e l y approximates the knee extensor and f l e x o r l e n g t h - t e n s i o n s h i p s t h a t are present d u r i n g  running.  relation-  Many p r e v i o u s  studies  have not c o n s i d e r e d examining KE and KF i n p o s i t i o n s which simulate l e n g t h - t e n s i o n occur during  r e l a t i o n s h i p s s i m i l a r t o those which  running even though they r e l a t e t h e i r r e s u l t s t o  a t h l e t e s who compete i n a c t i v i t i e s which these occur.  relationships  This must be performed i f the r e s u l t s a r e t o be used as  a database t o a i d coaches, t r a i n e r s , and/or p h y s i o t h e r a p i s t s determining i f an a t h l e t e  i s prepared to w i t h s t a n d the  experienced during t h e i r p a r t i c u l a r This must be  i n v e s t i g a t i o n has  aim  several  q u e s t i o n s which  r e h a b i l i t a t i o n of a hamstring  muscle s t r a i n i n j u r e d a t h l e t e which la) Should we  forces  sport.  revealed  answered c o n c e r n i n g the  in  include:  f o r l e s s of a d e c l i n e  i n torque  as angular v e l o c i t y i n c r e a s e s ? b)  Is a d e c l i n e  i n torque w i t h i n c r e a s i n g  v e l o c i t y r e l a t e d t o the  incidence  angular  of hamstring  MSI? 2)  Should we  aim  f o r an i n c r e a s e  i n the KF-E  t o l e v e l s beyond those e s t a b l i s h e d  ratio  for similar  individuals? 3a) b)  What r o l e does the e c c e n t r i c KF/E Should a h i g h e c c e n t r i c r a t i o be  r a t i o play? achieved  and  maintained? U n t i l such i n v e s t i g a t i o n has of u s i n g KF-E  r a t i o s and  assess the p r o g r e s s and itation is  i n d i v i d u a l muscle torque scores t o r e a d i n e s s of an a t h l e t e d u r i n g r e h a b i l -  r a t i o s , however, cannot be  c o n s i d e r e d as b e i n g  only f a c t o r which d i c t a t e s whether or not  w i l l sustain fatigue,  practice  speculative.  Knee F-E the  been performed the  a hamstring MSI.  flexibility,  The  an  individual  e f f e c t ( s ) of muscular  and  asynchronous n e u r a l s t i m u l a t i o n  of  i n d i v i d u a l muscles w i t h i n  a muscle group, i n combination,  or  a s s o c i a t e d w i t h a KF-E asymmetry must a l s o be c o n s i d e r e d as having  some r e l a t i o n s h i p with the i n c i d e n c e o f hamstring  Therefore,  r e s e a r c h must a l s o be performed which examines these  possible factors.  Although  much has been d i s c o v e r e d about the  way i n which muscle f u n c t i o n s d u r i n g a t h l e t i c a c t i v i t y still  there  remains many unanswered q u e s t i o n s as t o how events  as muscle s t r a i n i n j u r i e s o f the hamstring occur.  MSI.  muscle complex  I t i s only through comprehensive r e s e a r c h t h a t  q u e s t i o n s w i l l be answered.  such  these  Chapter 5 SUMMARY AND CONCLUSIONS  Summary The main purpose ionship  o f t h i s study was t o examine t h e r e l a t -  between c o n c e n t r i c  and e c c e n t r i c  torque as produced by  the knee f l e x o r s and extensors over t h r e e d i f f e r e n t v e l o c i t i e s of c o n t r a c t i o n athletes,  i n t h r e e d i f f e r e n t groups  aerobically trained  athletes,  of subjects:  power  and moderately  active  individuals. S i x t y s u b j e c t s were separated evenly among t h e t h r e e groups  following  vertical  physiological  assessment  jump and VO2 max t e s t s .  consisting  o f the  Anthropometric measurements  were taken t o estimate the s k e l e t a l muscle mass f o r each s u b j e c t and i s o k i n e t i c c o n c e n t r i c  and e c c e n t r i c  torque was  measured at 90, 1 3 5 , and 180 deg/sec"-*- f o r each o f the knee e x t e n s o r s and f l e x o r s .  F o r both muscle groups, t e s t i n g was  performed w i t h 10° o f h i p f l e x i o n , t h e knee extensors examined i n a supine t e s t p o s i t i o n w h i l e the knee f l e x o r s were assessed f o r torque p r o d u c t i o n i n a prone  position.  I s o k i n e t i c t e s t i n g r e s u l t s showed t h a t s i g n i f i c a n t l y g r e a t e r average c o n c e n t r i c  t h e PA produced  and e c c e n t r i c  torque  f o r both groups o f muscle at each angular v e l o c i t y than t h e ATR or MA groups and e c c e n t r i c  (p< 0 . 0 5 ) .  As w e l l ,  calculated  KF-E  concentric  r a t i o s were s i g n i f i c a n t l y g r e a t e r f o r the PA  group than t h e MA or ATR groups  (p< 0.01) at each angular  velocity. I t was  a l s o found t h a t  f o r each of the t h r e e groups of  s u b j e c t s i s o k i n e t i c torque produced t r i c a l l y by the KE was  c o n c e n t r i c a l l y and  eccen-  s i g n i f i c a n t l y g r e a t e r (p< 0.001)  t h a t produced by the KF.  E c c e n t r i c KF-E  than  r a t i o s were s i g n i f -  i c a n t l y g r e a t e r (p< 0.001) f o r each group at a l l v e l o c i t i e s of c o n t r a c t i o n than as compared t o measured c o n c e n t r i c angular v e l o c i t y i n c r e a s e d ,  concentric  corresponding s i g n i f i c a n t increase  ratios.  r a t i o s demonstrated  (p< 0.02)  As  a  while e c c e n t r i c  r a t i o s d i d not s i g n i f i c a n t l y d i f f e r w i t h changes i n angular velocity. Pearson Product c o r r e l a t i o n s showed t h a t vertical  jumping a b i l i t y was  f o r t h i s study  s i g n i f i c a n t l y c o r r e l a t e d w i t h the  a b i l i t y o f the knee extensors and f l e x o r s t o generate t r i c and e c c e n t r i c torque w h i l e v e r t i c a l  concen-  jumping a b i l i t y ê  not s i g n i f i c a n t l y c o r r e l a t e d with e i t h e r VO2 max  or  was  SMM.  Conclusions 1.  S i g n i f i c a n t d i f f e r e n c e s e x i s t e d between the power group and the moderately  a c t i v e and a e r o b i c a l l y t r a i n e d  groups i n a b i l i t y t o produce  concentric  and  runner  eccentric  i s o k i n e t i c average torque f o r both the knee e x t e n s o r s f l e x o r s at a l l angular v e l o c i t i e s .  There were no  i c a n t d i f f e r e n c e s between the a e r o b i c a l l y t r a i n e d and moderately  a c t i v e groups i n c o n c e n t r i c  torque p r o d u c t i o n .  and  signifrunner  or e c c e n t r i c  2.  F o r both t h e knee extensors and f l e x o r s c o n c e n t r i c average i s o k i n e t i c torque s i g n i f i c a n t l y decreased as t h e 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 i n a l l t h r e e groups o f s u b j e c t s . E c c e n t r i c average  i s o k i n e t i c torque, however, d i d not  s i g n i f i c a n t l y i n c r e a s e nor decrease  f o r any o f t h e three  groups o f s u b j e c t s . 3.  The power group's KF-E r a t i o s were s i g n i f i c a n t l y g r e a t e r both 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 a t each angular v e l o c i t y than e i t h e r t h e a e r o b i c a l l y t r a i n e d runner or moderately  a c t i v e groups o f s u b j e c t s .  These l a s t two  groups not b e i n g s i g n i f i c a n t l y d i f f e r e n t 4.  from one another.  Average i s o k i n e t i c c o n c e n t r i c and e c c e n t r i c torque f o r the knee extensors and f l e x o r s i s s i g n i f i c a n t l y with v e r t i c a l  correlated  jumping a b i l i t y while e s t i m a t e d  muscle mass and VO2 max i s not s i g n i f i c a n t l y  skeletal correlated.  RECOMMENDATIONS  1.  F u r t h e r r e s e a r c h should be performed  which measures i s o -  k i n e t i c c o n c e n t r i c and e c c e n t r i c knee extensor and f l e x o r torque and t h e i r r a t i o s i n a t e s t i n g p o s i t i o n which best s i m u l a t e s the l e n g t h t e n s i o n r e l a t i o n s h i p found d u r i n g running. 2.  I n c l u s i o n o f a p r e - t e s t p r a c t i c e s e s s i o n which would allow s u b j e c t s t o become f a m i l i a r w i t h producing assisted eccentric contractions.  mechanically  3.  I n s t e a d of c a l c u l a t i n g torque c o r r e c t e d f o r body weight, s k e l e t a l muscle mass, or lean body mass examine  thigh  muscle girths/mass and r e l a t e t h i s measure t o the amount of i s o k i n e t i c torque which can be 4.  produced.  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