INSERM U887, Université de Bourgogne, Dijon, France.
Scand J Med Sci Sports. 2011 Apr;21(2):268-76. doi: 10.1111/j.1600-0838.2009.01040.x.
The purpose of the present study was to compare the mechanisms of fatigue induced by a unilateral vs a bilateral submaximal isometric knee extension. Ten physically active men completed two experimental sessions, randomly presented. They were asked to maintain an isometric knee extension force corresponding to 20% of the maximal voluntary contraction (MVC) until task failure with one leg (unilateral) vs two legs (bilateral). MVCs were performed before and after the sustained contraction. Transcutaneous electrical stimuli were used to examine central (voluntary activation) and peripheral (peak doublet force at rest) fatigue on the exercised leg. Time to task failure was significantly shorter (P<0.05) for the bilateral (245 ± 76 s) compared with the unilateral task (295 ± 85 s). Unilateral MVC force and maximal voluntary activation losses were significantly greater (P<0.05) after the unilateral task than after the bilateral task. Peak doublet force was significantly reduced (P<0.01) after the unilateral task, but not after the bilateral task. The present results demonstrated that time to task failure of a submaximal fatiguing contraction may depend on the number of limbs involved in the task. The greater time to task failure with one leg may have induced greater contractile alterations and a larger MVC loss following the unilateral task.
本研究的目的是比较单侧和双侧次最大等长膝伸肌疲劳的机制。10 名体能活跃的男性完成了两次实验，随机呈现。他们被要求用一条腿（单侧）和两条腿（双侧）保持与最大自主收缩（MVC）的 20%相对应的等长膝伸肌力，直到任务失败。在持续收缩前后进行 MVC 测量。使用经皮电刺激来检查运动（自愿激活）和外周（休息时的双峰力峰值）在受影响的腿上的疲劳。双侧（245 ± 76 s）的任务失败时间明显短于单侧任务（295 ± 85 s）（P<0.05）。单侧 MVC 力和最大自愿激活损失在单侧任务后明显大于双侧任务（P<0.05）。单侧任务后，双峰力明显降低（P<0.01），但双侧任务后没有。本研究结果表明，次最大疲劳收缩的任务失败时间可能取决于参与任务的肢体数量。单侧任务的失败时间较长可能导致更大的收缩变化和单侧任务后更大的 MVC 损失。
