We investigated the characteristics for force generation and relaxation compared between upper and lower limb. Participants were instructed to control the force of isometric elbow flexion or knee extension as quickly and accurately as possible. They performed the following two tasks: 1) Generation task, they increased their force from 0% maximum voluntary force (MVF) to 20%, 40%, or 60% MVF, 2) Relaxation tasks, they decreased their force from 60% MVF to 40%, 20%, or to 0% MVF. As a result, variable error of upper limb was greater than that of lower limb at all magnitudes in generation task. The peak rate of force development was greater in lower limb than in upper limb at all magnitudes in both tasks. The results indicate that it is more difficult to control relaxation of force accurately by upper limb than by lower limb under conditions that involve forces with low magnitude of control.

中文翻译：

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上肢和下肢产生和松弛的力控制特性比较

我们研究了上肢和下肢之间的力生成和松弛特性。参与者被要求尽可能快速准确地控制等长肘关节屈曲或伸膝的力量。他们执行了以下两个任务：1) 生成任务，他们将他们的力量从 0% 最大自愿力量 (MVF) 增加到 20%、40% 或 60% MVF，2) 放松任务，他们从 60% MVF 减少他们的力量到 40%、20% 或 0% MVF。因此，在生成任务中，上肢的可变误差在所有量级上都大于下肢的可变误差。在这两项任务中，在所有幅度下，下肢的力量发展峰值速度都高于上肢。