Bulletin Autumn‧Winter 1998

compare the effects of different modes of treatment for sports injuries, or to correlate modes of exercise and training with the performance ofathletes. Its major advantages are effectiveness, reliability, objectivity, and non-invasiveness. From 1992 to 1995, Prof. Chan Kai-ming and his research team in the Department of Orthopaedics and Traumatology conducted a series of studies on the use of isokinetics in the assessment of muscle performance of different anatomical regions such as the knee, shoulder, ankle, and back, to define statistically the span ofnormality amongthe Chinese population, and to characterize muscle performance in sports injuries. The studies havelaid afirm scientific foundation for rehabilitative regimesutilizing various models of the Cybex machine. K n e e F l e x i on a n d Ex t en s i on : a R e l i a b i l i t y S t u d y U s i n g t he Cy b ex 6000 D y n a m o m e t e r This s t u d y sets o u t to test the reliability of the C y b e x 6000 isokinetic d y n a m o m e t e r , a ma c h i ne that is regarded as s h o w i n g h i g h r e l i a b i l i ty i n me a s u r i ng isokinetic variables o f c o n c e n t r i c a n d eccentric m o v e m e n t s— mo v eme n ts i n w h i c h muscle l e n g th shortens a n d lengthens respectively w h i l e contracting. Tests for the same isokinetic variables we r e repeatedly administered o n the same muscle groups. The mo re consistent or r e p r o d u c i b le the results, the m o r e r e l i a b l e is the C y b ex 6000 isokinetic d y n amome t e r . T h e s u b j e c ts w e r e 18 m a l e s w i t h a m e d i a n age of 27 a n d 12 f ema l e s w i t h a m e d i a n age of 26. T he f l e x o r a n d extensor muscle g r o u ps of b o th knees of the subjects w e r e tested r e p e a t e d ly f o r three measurements of muscle p e r f o r ma n c e—p e ak torque, t h e m a x i m a l f o r ce t h a t acts t o p r o d u c e a rotational mo v eme n t ; total w o r k , the s u m of w o r k (force x distance); a n d average p o w e r , w o r k over time. The subjects were positioned sitting at the ma c h i n e a n d we re requested to mo v e their legs f o r wa r ds or backwards u s i ng m a x i m a l effort against the a c c o mm o d a t i ng resistance at a preset speed a n d f o r a preset n u m b er of test repetitions . The results s h o w ed that the current test is s t a t i s t i c a l ly reliable i n o b t a i n i ng a l l the m e a s u r e d p a r a m e t e r s , a m o n g w h i c h me a s u r eme nt o n the knee extensor mu s c le h a d better repeatability t h a n that of the knee f l e x o r, a n d the c o n c e n t r i c m o d e of t e s t i n g wa s mo r e reproducible. I s o k i n e t ic S t r e n g t h o f t he Qu a d r i c e p s a n d H ams t r i n gs a n d F u n c t i o n a l A b i l i t y o f I n j u r ed Knee s i n Re c r ea t i onal A t h l e t es H ams t r i n gs a n d quadriceps are the sets of muscles located respectively a t the b a c k a n d i n the fron t of our thighs. The s t u d y tests the hypothesis that increasing the hamstrings a n d quadriceps isokinetic strength ratio (H:Q) t h r o u g h s t r e n g t h e n i n g t h e h a m s t r i n g s i mp r o v e s the functional ability of an anteriorcruciate l i g ame n t ( ACL ) deficient knee i n the short t e rm . R u p t u re of the anterior-cruciate l i g ame nt can result f r o m a direct b l o w to th e k n e e j o i n t w h i c h s t r e t c h e s t h e l i g a m e n t b e y o n d its p h y s i o l o g i c a l s t i f f n e s s, or t h e d i s t al a p p l i c a t i on of b e n d i ng a n d t w i s t i ng force to the limbs, or d u r i ng a s u d d en change i n d i r e c t i o n or deceleration. F o r t y - s i x r e c r e a t i o n a l a t h l e t es w i t h completely t o rn ligaments we r e recruited for the s t u d y. T h e mu s c l e p e r f o r ma n ce of th e subjects w a s m e a s u r ed i n t e r ms of p e a k t o r q u e, e n d u r a n c e r a t i o, t o t a l w o r k , a n d explosive p owe r . The functional ability of the Isokinetic Technology—Applications in Sports Medicine and Sports Science 35