Jones C, Allen T, Talbot J, Morgan D L, Proske U
Department of Physiology and Electrical and Computer Systems Engineering, Monash University, Victoria, Australia.
Eur J Appl Physiol Occup Physiol. 1997;76(1):21-31. doi: 10.1007/s004210050208.
Following a series of eccentric contractions, that is stretching of the muscle while generating active tension, the length-tension relationship of isolated amphibian muscle has been shown to shift towards longer muscle length (Katz 1939; Wood et al. 1993). Here we report observations of electrically stimulated ankle extensor muscles of nine human subjects, demonstrating a similar shift in optimum angle for torque generation [3.9 (1.5) degrees] following exercise on an inclined treadmill that involved eccentric contractions in one leg. (All values are means with the SEMs in parentheses). The shift in the unexercised, control leg was significantly less [mean 0.4 (0.7) degree P < 0.05]. Correlated with this shift was a drop in torque [25.1 (5.6)% for the experimental leg; 1.6 (0.7)% for the control leg, P < 0.002]. Optimum angles returned to pre-exercise values by 2 days post-exercise, while torque took a week to recover. A similar shift in optimum length [12 (1.3)% of rest length] was obtained for five toad (Bufo marinus) sartorius muscles subjected to 25 eccentric contractions. Isometrically contracted control muscles showed a smaller shift [3.5 (1.6)%, n = 5]. Accompanying the shift was a drop in tension of 46 (3)% after the eccentric contractions [control isometric, 23 (6)%, P < 0.0001]. By 5 h after the eccentric contractions the shift had returned to control values, while tension had not recovered. When viewed with an electron microscope, sartorius muscles fixed immediately after the eccentric contractions exhibited many small, and a few larger, regions of myofilament disruption. In muscles fixed 5 h after the contractions, no small regions of disruption were visible, and the number of large regions was no greater than in those muscles fixed immediately after the eccentric contractions. These disruptions are interpreted as the cause of the shift in length-tension relationship.
在经历一系列离心收缩（即在产生主动张力的同时肌肉被拉伸）后，已表明离体两栖类肌肉的长度 - 张力关系会向更长的肌肉长度方向移动（Katz，1939年；Wood等人，1993年）。在此，我们报告了对9名人类受试者的电刺激踝伸肌的观察结果，表明在涉及单腿离心收缩的倾斜跑步机上运动后，产生扭矩的最佳角度出现了类似的移动[3.9（1.5）度]。（所有数值均为均值，括号内为标准误）。未运动的对照腿的移动明显较小[均值0.4（0.7）度，P < 0.05]。与这种移动相关的是扭矩下降[实验腿为25.1（5.6）%；对照腿为1.6（0.7）%，P < 0.002]。最佳角度在运动后2天恢复到运动前的值，而扭矩则需要一周时间恢复。对5条蟾蜍（海蟾蜍）缝匠肌进行25次离心收缩后，获得了类似的最佳长度移动[休息长度的12（1.3）%]。等长收缩的对照肌肉显示出较小的移动[3.5（1.6）%，n = 5]。伴随这种移动的是离心收缩后张力下降46（3）%[对照等长收缩为23（6）%，P < 0.0001]。在离心收缩后5小时，移动已恢复到对照值，而张力尚未恢复。用电子显微镜观察时，在离心收缩后立即固定的缝匠肌显示出许多小的以及一些较大的肌丝破坏区域。在收缩后5小时固定的肌肉中，看不到小的破坏区域，并且大区域的数量并不比在离心收缩后立即固定的肌肉中的数量多。这些破坏被解释为长度 - 张力关系移动的原因。
