Effects of contraction mode and stimulation frequency on electrical stimulation-induced skeletal muscle hypertrophy
Effects of contraction mode and stimulation frequency on electrical stimulation-induced skeletal muscle hypertrophy
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DOI：
10.1152/japplphysiol.00708.2017
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发表时间：
2018-02-01
影响因子：
3.3
通讯作者：
Yamada, Takashi
中科院分区：
文献类型：
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作者：
Ashida, Yuki;Himori, Koichi;Yamada, Takashi
我们比较了不同电刺激频率下等距（Iso）或偏心（Ecc）电刺激（ES）训练引起的骨骼肌肥大。雄性Wistar大鼠分为Iso组和Ecc组。这些被试又被分成三个亚组，分别在10赫兹（Iso-10和ec -10）、30赫兹（Iso-30和ec -30）和100赫兹（Iso-100和ec -100）下进行刺激。实验1每隔一天刺激左跖屈肌，持续3周。在实验2中，研究了哺乳动物雷帕霉素复合物1 （mTORC1）信号通路在一次ES后6小时的靶点。对侧右肌作为对照（非es）。Ecc收缩包括强制背屈和ES。在所有测试的刺激频率中，Ecc组在ES期间的峰值扭矩和扭矩-时间积分都高于Iso组。ec -30、Iso-100和ec -100组ES侧腓肠肌重量与体重的比例分别比非ES侧增加了6%、7%和17%，其中ec -100组的增幅大于ec -30和Iso-100组。ec -30和-100组的p70S6K （Thr389）磷酸化水平分别高于Iso-30和-100组。峰值扭矩和扭矩-时间积分与肌肉质量的增加幅度和p70S6K的磷酸化高度相关。这些数据表明，es诱导的肌肉肥大和mTORC1活性是由肌肉收缩时的负荷强度和体积决定的，与收缩模式无关。离心收缩和高频刺激（HFS）被认为是通过电刺激（ES）训练增加肌肉质量的有效方法。然而，关于肌痉挛训练中肌肉肥大是否受收缩方式和刺激频率的影响，目前知之甚少。在这里，我们提供的证据表明，肌肉肥大和哺乳动物雷帕霉素复合物1活性的目标是由收缩期间的机械负荷决定的，而不是由收缩模式本身决定的，在HFS时获得更大的增益。
We compared the skeletal muscle hypertrophy resulting from isometric (Iso) or eccentric (Ecc) electrical stimulation (ES) training with different stimulation frequencies. Male Wistar rats were assigned to the Iso and Ecc groups. These were divided into three further subgroups that were stimulated at 10 Hz (Iso-10 and Ecc-10), 30 Hz (Iso-30 and Ecc-30), or 100 Hz (Iso-100 and Ecc-100). In experiment 1, the left plantarflexor muscles were stimulated every other day for 3 wk. In experiment 2, mammalian target of rapamycin complex 1 (mTORC1) signaling was investigated 6 h after one bout of ES. The contralateral right muscle served as a control (non-ES). Ecc contractions comprised forced dorsiflexion combined with ES. The peak torque and torque-time integral during ES were higher in the Ecc group than that in the Iso group in all stimulation frequencies examined. The gastrocnemius muscle weight normalized to body weight in ES side was increased compared with the non-ES side by 6, 7, and 17% in the Ecc-30, Iso-100, and Ecc-100 groups, respectively, with a greater gain in Ecc-100 than the Ecc-30 and Iso-100 groups. The p70S6K (Thr389) phosphorylation level was higher in the Ecc-30 and -100 than in the Iso-30 and -100 groups, respectively. The peak torque and torque-time integral were highly correlated with the magnitude of increase in muscle mass and the phosphorylation of p70S6K. These data suggest that ES-induced muscle hypertrophy and mTORC1 activity are determined by loading intensity and volume during muscle contraction independent of the contraction mode.NEW & NOTEWORTHY Eccentric contraction and high-frequency stimulation (HFS) are regarded as an effective way to increase muscle mass by electrical stimulation (ES) training. However, little is known about whether muscle hypertrophy is affected by contraction mode and stimulation frequency in ES training. Here, we provide the evidence that muscle hypertrophy and mammalian target of rapamycin complex 1 activity are determined by mechanical loading during contraction but not on the contraction mode itself, with a greater gain at HFS.