Effects of muscle activation on fatigue and metabolism in human skeletal muscle
Effects of muscle activation on fatigue and metabolism in human skeletal muscle
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DOI：
10.1152/japplphysiol.00483.2001
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发表时间：
2002-05-01
影响因子：
3.3
通讯作者：
Binder-Macleod, SA
中科院分区：
文献类型：
--
作者：
Russ, DW;Vandenborne, K;Binder-Macleod, SA
增加刺激频率已被证明会增加疲劳，但当与频率变化相关的力的变化已被控制时则不会。频率的影响，独立于力，可能与额外激活导致的代谢成本相关。在这里，对人内侧腓肠肌进行了两个单独的实验。第一个实验（n = 8）被设计为测试脉冲数对疲劳的影响。在两个重复的，150列刺激协议，产生相等的初始力，一个使用80 Hz的列车和其他使用100 Hz的列车，力的下降进行了比较。尽管有600次脉冲（23.5%）的差异，但两种方案产生的疲劳率和疲劳量相似。在第二个实验中，旨在测试脉冲数对收缩代谢成本的影响，在两个缺血性的8串刺激方案（80和100 Hz）期间收集P-31-NMR光谱（n = 6），尽管有320个脉冲的差异（24.8%），但产生了可比较的力。在P-I浓度、磷酸肌酸浓度和细胞内pH值的变化或两种列车产生的ATP周转率方面没有发现差异。这些结果表明，刺激频率对疲劳的影响与产生的力有关，而不是与激活次数有关。此外，在测试的频率范围内，增加总激活并不增加代谢成本。
Increasing stimulation frequency has been shown to increase fatigue but not when the changes in force associated with changes in frequency have been controlled. An effect of frequency, independent of force, may be associated with the metabolic cost resulting from the additional activations. Here, two separate experiments were performed on human medial gastrocnemius muscles. The first experiment (n = 8) was designed to test the effect of the number of pulses on fatigue. The declines in force during two repetitive, 150-train stimulation protocols that produced equal initial forces, one using 80-Hz trains and the other using 100-Hz trains, were compared. Despite a difference of 600 pulses (23.5%), the protocols produced similar rates and amounts of fatigue. In the second experiment, designed to test the effect of the number of pulses on the metabolic cost of contraction, P-31-NMR spectra were collected (n = 6) during two ischemic, eight-train stimulation protocols (80- and 100-Hz) that produced comparable forces despite a difference of 320 pulses (24.8%). No differences were found in the changes in P-i concentration, phosphocreatine concentration, and intracellular pH or in the ATP turnover produced by the two trains. These results suggest that the effect of stimulation frequency on fatigue is related to the force produced, rather than to the number of activations. In addition, within the range of frequencies tested, increasing total activations did not increase metabolic cost.