Ruiter C J, Didden W J, Jones D A, Haan A D
Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
J Physiol. 2000 Aug 1;526 Pt 3(Pt 3):671-81. doi: 10.1111/j.1469-7793.2000.00671.x.
We have examined the force-velocity characteristics of tetanically activated human adductor pollicis working in vivo, in the fresh and fatigued states. The increase in force in response to stretch was divided into two major components. The first, steady, component persisted after the stretch and is concluded not to be a function of active cycling cross-bridges because it was not affected by either the velocity of the stretch or the level of muscle activation. The origin of the second, transient, component of the increased force seen during stretch is consistent with cross-bridge activity since it increased with increasing velocity of stretch and was proportional to the level of activation. It is likely that both components of the stretch response make a significant contribution to muscle performance when acting to resist a force. For the fastest stretch used, the contributions of cross-bridge and non-cross-bridge mechanisms were equal. For the slowest stretch, lasting 10 s and over the same distance, the force response was attributed almost entirely to non-cross-bridge mechanisms. As a result of acute fatigue (50 % isometric force loss) there were only small reductions in the non-cross-bridge component of the force response to stretch, while the cross-bridge component decreased in absolute terms. The transient component of the stretch response increased as a result of fatigue, relative to the isometric force, while the force during shortening decreased. The results are consistent with a decrease in cross-bridge turnover in fatigued muscle.
我们研究了在新鲜和疲劳状态下，人体拇收肌在体内强直激活时的力-速度特性。拉伸引起的力增加分为两个主要部分。第一部分是稳定的，在拉伸后持续存在，并且得出结论认为它不是主动循环横桥的函数，因为它不受拉伸速度或肌肉激活水平的影响。拉伸过程中看到的力增加的第二部分是短暂的，其起源与横桥活动一致，因为它随着拉伸速度的增加而增加，并且与激活水平成正比。当用于抵抗外力时，拉伸反应的这两个部分可能都对肌肉性能有显著贡献。对于使用的最快拉伸，横桥和非横桥机制的贡献相等。对于持续10秒且在相同距离上的最慢拉伸，力反应几乎完全归因于非横桥机制。急性疲劳（等长力损失50%）导致拉伸力反应的非横桥部分仅有小幅降低，而横桥部分绝对值下降。相对于等长力，拉伸反应的短暂部分因疲劳而增加，而缩短过程中的力则下降。这些结果与疲劳肌肉中横桥周转率降低一致。
