Influence of aging on sex differences in muscle fatigability
Influence of aging on sex differences in muscle fatigability
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DOI：
10.1152/japplphysiol.00460.2004
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发表时间：
2004-11-01
影响因子：
3.3
通讯作者：
Enoka, RM
中科院分区：
文献类型：
--
作者：
Hunter, SK;Critchlow, A;Enoka, RM
本研究的目的是比较年轻和老年男性和女性肘关节屈肌在次最大强度下进行持续等距收缩的时间和任务失败。27名年轻人（14名男性和13名女性，18-35岁）和18名老年人（10名男性和8名女性，65-80岁）以最大自主收缩扭矩的20%进行等距收缩，直到目标扭矩不能再达到大于或等于5秒。青壮年比老年人强壮（66.8 +/- 17.9比47.7 +/- 18.1 N.m, P < 0.05），男性比女性强壮（69.8±17.9比47.1±15.3 N.m, P < 0.05），年龄和性别之间无交互作用（P < 0.05）。老年人的任务失败时间比年轻人长（22.8 +/- 9.1 vs. 14.4 +/- 7.6 min, P < 0.05），年轻女性的任务失败时间比年轻男性长（18.3±8.0 vs. 10.8±5.2,P < 0.05），但老年女性和男性之间无差异（分别为21.3 +/- 10.7和24.1 +/- 8.0 min, P < 0.05），年轻女性和老年人之间无差异（P < 0.05）。疲劳收缩时肘关节屈肌平均动脉压、心率、平均肌电活动和扭矩波动均增加（P < 0.05）。年轻男性和老年人的平均动脉压、心率和扭矩波动的增加率更高，而老年男性和女性之间没有差异（P < 0.05）。同样，年轻男性的肌电活动增加率也高于其他三组。老年人在疲劳收缩结束时肌电图爆发频率较低（P < 0.05），这伴随着扭矩波动的减少。因此，任务失败的时间与年轻人的目标扭矩有关，但与老年人无关，任务持续时间的差异伴随着压力反应的平行变化。
The purpose of this study was to compare time to task failure for a sustained isometric contraction performed at a submaximal intensity with elbow flexor muscles by young and old men and women. Twenty-seven young (14 men and 13 women, 18-35 yr) and 18 old (10 men and 8 women, 65-80 yr) adults sustained an isometric contraction at 20% of maximal voluntary contraction torque until target torque could no longer be achieved for greater than or equal to5 s. Young adults were stronger than old adults (66.8 +/- 17.9 vs. 47.7 +/- 18.1 N.m, P < 0.05), and men were stronger than women (69.8 ± 17.9 vs. 47.1 ± 15.3 N.m, P < 0.05), with no interaction between age and sex (P > 0.05). Time to task failure was longer for old than for young adults (22.8 +/- 9.1 vs. 14.4 +/- 7.6 min, P < 0.05) and for young women than for young men (18.3 ± 8.0 vs. 10.8 ± 5.2, P < 0.05), but there was no difference between old women and men (21.3 +/- 10.7 and 24.1 +/- 8.0 min, respectively, P > 0.05) or between young women and old adults (P > 0.05). Mean arterial pressure, heart rate, average electromyographic (EMG) activity, and torque fluctuations of elbow flexor muscles increased during the fatiguing contraction (P < 0.05) for all subjects. Rates of increase in mean arterial pressure, heart rate, and torque fluctuations were greater for young men and old adults, with no differences between old men and women (P > 0.05). Similarly, the rate of increase in EMG activity was greater for young men than for the other three groups. EMG bursts were less frequent for old adults (P < 0.05) at the end of the fatiguing contraction, and this was accompanied by reduced fluctuations in torque. Consequently, time to task failure was related to target torque for young, but not old, adults, and differences in task duration were accompanied by parallel changes in the pressor response.