Human skeletal muscle responses vary with age and gender during fatigue due to incremental isometric exercise
Human skeletal muscle responses vary with age and gender during fatigue due to incremental isometric exercise
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DOI：
10.1152/japplphysiol.00091.2002
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发表时间：
2002-11-01
影响因子：
3.3
通讯作者：
Towse, TF
中科院分区：
文献类型：
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作者：
Kent-Braun, JA;Ng, AV;Towse, TF
本研究的目的是比较20名年轻（33 +/- 6岁，平均值+/- SD）和21名老年（75 +/- 6岁）健康男性和女性的踝关节背屈肌疲劳的程度和机制。在增量等长运动之前、期间和之后，对中枢和外周（神经肌肉接头、肌膜）肌肉激活、肌肉收缩功能和肌内能量代谢进行无创测量。老年受试者的疲劳程度低于年轻受试者（P < 0.01）;性别对疲劳没有影响（P = 0.24）。对于所有受试者，疲劳与运动前力量适度相关（r = 0.49，P < 0.01）。无论是中央（中央激活率）或周边（复合肌肉动作电位）激活在任何组的疲劳中发挥了重要作用。在运动过程中，青年组与老年组相比（P <0.01），男性组与女性组相比（P <0.01），细胞内Pi和H2 PO 4-浓度升高幅度更大，pH值下降幅度更大。这些不同的运动代谢反应表明，与老年受试者相比，年轻人更依赖于ATP的非氧化来源，男性比女性更依赖于ATP的非氧化来源。这些结果表明，疲劳的机制随年龄和性别而变化，无论是否观察到疲劳程度的差异。
The purpose of this study was to compare the magnitude and mechanisms of ankle dorsiflexor muscle fatigue in 20 young (33 +/- 6 yr, mean +/- SD) and 21 older (75 +/- 6 yr) healthy men and women of similar physical activity status. Noninvasive measures of central and peripheral (neuromuscular junction, sarcolemma) muscle activation, muscle contractile function, and intramuscular energy metabolism were made before, during, and after incremental isometric exercise. Older subjects fatigued less than young (P < 0.01); there was no effect of gender on fatigue (P = 0.24). For all subjects combined, fatigue was modestly related to preexercise strength (r = 0.49, P < 0.01). Neither central (central activation ratio) nor peripheral (compound muscle action potential) activation played a significant role in fatigue in any group. During exercise, intracellular concentrations of Pi and H2PO4- increased more and pH fell more in young compared with older subjects (P < 0.01) and in men compared with women (P < 0.01). These varied metabolic responses to exercise suggest a greater reliance on nonoxidative sources of ATP in young compared with older subjects and in men compared with women. These results suggest that the mechanisms of fatigue vary with age and gender, regardless of whether differences in the magnitude of fatigue are observed.