Issn Print: 0195-9131
Publication Date: 1996/05/01
DIFFERENTIAL EFFECT OF ACTIVITY IN THE CONTRALATERAL LEG ON THE MAXIMUM PERFORMANCE OF THE KNEE EXTENSORS IN STATIC AND DYNAMIC CONTRACTIONS1218
T. Nishikawa; W. Kakihana; S. Suzuki
Excerpt
The purpose was to determine the effect of contracting muscles in the left leg on the maximum performance of the knee extensors in the right leg during static and dynamic contractions. Thirteen college-aged male subjects performed static and dynamic contractions on a strength-training device (Nishi Sports). The knee extensors of the right leg performed two tasks: maximum-force static(isometric) contractions for 5 s and maximum-speed dynamic contractions against a load of about 30% of the maximum voluntary contraction (MVC) force. The dynamic contractions were performed rapidly after an auditory signal. For each of the right-leg tasks, the left leg concurrently achieved three conditions: relaxed (A), lightly touched a reference bar (B), and exerted a maximum knee-flexor torque (C). For conditions B and C, the knee joint of the left leg was extended by about 10° from the relaxed position. Knee-joint angle for the right leg was set at about 90° for the static contractions and began at about 90° for the dynamic contractions. The outcome variables included peak force, time to peak force, and peak acceleration about the knee joint; the latter was determined by video analysis of the movement (Oyo Keisoku). For the static contractions, the maximal force (mean ± SD) was 652 ± 122 N (A), 659 ± 119 N (B), and 628 ± 106 N(C). The maximum force for condition C was significantly less than that for condition B, but none of the other comparisons were statistically different. The time taken to reach the peak force was not different across the three conditions (2.4 - 2.8 s). For the dynamic contractions, the peak accelerations was 49.57 ± 9.63 (A), 51.92 ± 9.39 (B), and 55.66 ± 9.15(C) rad/s2. The peak acceleration for condition C was significantly greater than those for conditions A and B. These data indicate that the activity in one leg can affect the maximum performance capability of the other leg, but that the effect differs for static and dynamic contractions.
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