Recent studies have documented increased multi-directional laxity in the knee and a reduction in muscular strength following exercise. The objectives of this study were to evaluate the effects of fatiguing-practice on lower extremity response in closed kinetic chain. Using a computerized system with two force platforms, subjects stood on these platforms and were instructed to shift their weight from one foot to another or jump as fast as possible following a sudden display of computer instructions which was randamly arranged. The parameters examined were: 1) reverse response time (RRT); time between the presentation of a stimulus and the beginning of the reverse response, 2) peak reverse value (PRV), 3) response time (RT); time between the presentation of a stimulus and the beginning of the shift in the opposite direction, and 4) gradient of shift (GS); acceleration of weight shift. Twenty-three university basketball players (thirteen women and ten men) with their average age being 20 years were tested before, during, and after practice of basketball. Testing took place in a gymnasium and the room temperature was at 12°C. In addition, a group of 11 other healthy volunteers, all of them being physiotheraphy students, were studied for two consecutive days in order to evaluate retest reliability for the measurements included in the study. There were test-retest reliability in RRT, RT, and GS. RRT and GS did not change due to fatiguing practice. No significant difference was found between women and men in any parameter. There were significant improvement in RT between pre- and during-practice (p<0.05) in women. pre- and after-practice (p<0.01), and during- and after-practice (p<0.05) in men. The results obtained from this study were probably affected by two factors. 1) Because of the chill room temperature, warming with practice increased the extensibility of the musculotendinous unit. 2) Practice facillitated special neuromuscular coordination. These factors might thereby improve the response, however, no trends in these value may be identified due to the small sample size.
