Gender differences in skeletal muscle fatigability are related to contraction type and EMG spectral compression
Gender differences in skeletal muscle fatigability are related to contraction type and EMG spectral compression
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DOI：
10.1152/japplphysiol.00926.2002
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发表时间：
2003-06-01
影响因子：
3.3
通讯作者：
Ploutz-Snyder, LL
中科院分区：
文献类型：
--
作者：
Clark, BC;Manini, TM;Ploutz-Snyder, LL
本研究的目的是：1）评估等长和等张肌肉收缩过程中背伸肌耐力的性别差异，2）确定绝对负荷和耐力时间之间的关系，3）比较男性[n = 10，年龄22.4 +/- 0.69（SE）yr]和女性（n = 10，年龄21.7 +/- 1.07岁）的神经肌肉激活模式和中位频率（MF）的变化，在疲劳的次最大等长躯干伸展运动的腰和髋伸肌肌电图（EMG）功率谱。受试者进行等张和等长躯干伸展运动，以最大随意收缩力的50%至肌肉衰竭。女性在等长任务中表现出比男性更长的耐力时间（146.0 +/- 10.9对105.4 +/- 7.9 s），但在等张运动中的耐力表现没有差异（24.3 +/- 3.4对24.0 +/- 2.8重复）。绝对负荷与合并样本中的等长耐力时间显著相关（R-2 = 0.34），但当男性和女性分别进行分析时则不相关（R-2 = 0.05和0.04，分别）。EMG数据显示神经肌肉激活模式没有差异;然而，观察到MF变化的性别差异。女性表现出类似的疲劳性股二头肌和腰伸肌，而在男性中，疲劳性是更明显的腰部肌肉比股二头肌。此外，腰椎伸肌的MF与男性的耐受时间的相关性大于女性（R-2 = 0.45 vs. 0.19）。这些研究结果表明，肌肉疲劳的性别差异的影响，肌肉收缩类型和频率变化的EMG信号，但不是由协同激活模式的改变。
The purposes of this study were 1) to evaluate gender differences in back extensor endurance capacity during isometric and isotonic muscular contractions, 2) to determine the relation between absolute load and endurance time, and 3) to compare men [n = 10, age 22.4 +/- 0.69 (SE) yr] and women (n = 10, age 21.7 +/- 1.07 yr) in terms of neuromuscular activation patterns and median frequency (MF) shifts in the electromyogram (EMG) power spectrum of the lumbar and hip extensor muscles during fatiguing submaximal isometric trunk extension exercise. Subjects performed isotonic and isometric trunk extension exercise to muscular failure at 50% of maximum voluntary contraction force. Women exhibited a longer endurance time than men during the isometric task (146.0 +/- 10.9 vs. 105.4 +/- 7.9 s), but there was no difference in endurance performance during the isotonic exercise (24.3 +/- 3.4 vs. 24.0 +/- 2.8 repetitions). Absolute load was significantly related to isometric endurance time in the pooled sample (R-2 = 0.34) but not when men and women were analyzed separately (R-2 = 0.05 and 0.04, respectively). EMG data showed no differences in neuromuscular activation patterns; however, gender differences in MF shifts were observed. Women demonstrated a similar fatigability in the biceps femoris and lumbar extensors, whereas in men, the fatigability was more pronounced in the lumbar musculature than in the biceps femoris. Additionally, the MF of the lumbar extensors demonstrated a greater association with endurance time in men than in women (R-2 = 0.45 vs. 0.19). These findings suggest that gender differences in muscle fatigue are influenced by muscle contraction type and frequency shifts in the EMG signal but not by alterations in the synergistic activation patterns.