Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 110 Ruth Leverton Hall, Lincoln, NE 68583-0806, United States of America. Author to whom any correspondence should be addressed.
Physiol Meas. 2019 Mar 13;40(2):025009. doi: 10.1088/1361-6579/ab057e.
The purpose of this investigation was to examine the ability of the electromyographic (EMG) and mechanomyographic (MMG) amplitude versus torque relationships to track group and individual changes in muscle hypertrophy as a result of resistance training.
Twelve women performed four weeks of forearm flexion blood flow restriction (BFR) resistance training at a frequency of three times per week. The training was performed at an isokinetic velocity of 120° · s with a training load that corresponded to 30% of concentric peak torque. Muscle hypertrophy was determined using ultrasound-based assessments of muscle cross-sectional area from the biceps brachii. Training-induced changes in the slope coefficients of the EMG amplitude and MMG amplitude versus torque relationships were determined from the biceps brachii during incremental (10%-100% of maximum) isometric muscle actions.
There was a significant (p < 0.001; d = 2.15) mean training-induced increase in muscle cross-sectional area from 0 week (mean ± SD = 5.86 ± 0.65 cm) to 4 weeks (7.42 ± 0.80 cm), a significant (p = 0.023; d = 0.36) decrease in the EMG amplitude versus torque relationship (50.70 ± 20.41 to 43.82 ± 17.76 µV · Nm), but no significant (p = 0.192; d = 0.17) change in the MMG amplitude versus torque relationship (0.018 ± 0.009 to 0.020 ± 0.009 m · s · Nm). There was, however, great variability for the individual responses for the EMG and MMG amplitude versus torque relationships.
The results of the present study indicated that the EMG amplitude, but not the MMG amplitude versus torque relationship was sensitive to mean changes in muscle cross-sectional area during the early-phase of resistance training. There was, however, great variability for the individual EMG amplitude versus torque relationships that limits its application for identifying individual changes in muscle hypertrophy as a result of BFR.
本研究旨在探讨肌电图（EMG）和肌动描记图（MMG）振幅与扭矩关系的能力，以跟踪由于抗阻训练而导致的肌肉肥大的群体和个体变化。
12 名女性进行了四周的前臂屈肌血流限制（BFR）抗阻训练，频率为每周三次。训练在等速速度为 120°·s 下进行，训练负荷相当于向心峰值扭矩的 30%。肱二头肌的超声测量评估肌肉横截面积来确定肌肉肥大。通过肱二头肌的递增（10%-100%最大）等长肌肉动作，确定 EMG 振幅和 MMG 振幅与扭矩关系的斜率系数在训练中的变化。
从 0 周（均值±标准差=5.86±0.65cm）到 4 周（7.42±0.80cm），肌肉横截面积有显著的（p<0.001；d=2.15）均值训练诱导增加，EMG 振幅与扭矩关系（50.70±20.41 至 43.82±17.76µV·Nm）显著降低（p=0.023；d=0.36），但 MMG 振幅与扭矩关系无显著变化（0.018±0.009 至 0.020±0.009 m·s·Nm）（p=0.192；d=0.17）。然而，EMG 和 MMG 振幅与扭矩关系的个体反应存在很大的变异性。
本研究结果表明，在抗阻训练的早期阶段，EMG 振幅而不是 MMG 振幅与扭矩关系对肌肉横截面积的平均变化敏感。然而，EMG 振幅与扭矩关系的个体变异性很大，限制了其在识别血流限制引起的肌肉肥大个体变化中的应用。
