Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; Centre of Sport Medicine, Don Gnocchi Foundation, Via Capecelatro 66, 20148 Milan, Italy.
J Electromyogr Kinesiol. 2013 Dec;23(6):1295-303. doi: 10.1016/j.jelekin.2013.09.007. Epub 2013 Oct 8.
To assess the validity and reliability of the mechanomyogram (MMG) as a tool to investigate the fatigue-induced changes in the muscle during relaxation, the torque and MMG signals from the gastrocnemius medialis muscle of 23 participants were recorded during tetanic electrically-elicited contractions before and immediately after fatigue, as well as at min 2 and 7 of recovery. The peak torque (pT), contraction time (CT) and relaxation time (RT), and the acceleration of force development (d2RFD) and relaxation (d2RFR) were calculated. The slope and τ of force relaxation were also determined. MMG peak-to-peak was assessed during contraction (MMG p-p) and relaxation (R-MMG p-p). After fatigue, pT, d2RFD, d2RFR, slope, MMG p-p and R-MMG p-p decreased significantly, while CT, RT and τ increased (P < 0.05 for all comparisons), remaining altered throughout the entire recovery period. R-MMG p-p correlated with pT, MMG p-p, slope, τ and d2RFR both before and after fatigue. Reliability measurements always ranged from high to very high. In conclusion, MMG may represent a valid and reliable index to monitor the fatigue-induced changes in muscle mechanical behavior, and could be therefore considered an effective alternative to the force signal, also during relaxation.
为了评估肌动描记图（MMG）作为一种研究肌肉在放松过程中疲劳诱导变化的工具的有效性和可靠性，我们记录了 23 名参与者的比目鱼肌在电诱发的强直性收缩前后、疲劳后即刻以及恢复 2 分钟和 7 分钟时的扭矩和 MMG 信号。计算了峰值扭矩（pT）、收缩时间（CT）和放松时间（RT），以及力发展的加速度（d2RFD）和放松（d2RFR）。还确定了力松弛的斜率和 τ。在收缩（MMG p-p）和放松（R-MMG p-p）期间评估 MMG 峰峰值。疲劳后，pT、d2RFD、d2RFR、斜率、MMG p-p 和 R-MMG p-p 显著降低，而 CT、RT 和 τ 增加（所有比较的 P < 0.05），在整个恢复期间仍然改变。R-MMG p-p 在疲劳前后与 pT、MMG p-p、斜率、τ 和 d2RFR 相关。可靠性测量值始终在高到非常高之间。总之，MMG 可能是监测肌肉机械行为疲劳诱导变化的有效且可靠的指标，因此在放松期间也可以被认为是力信号的有效替代指标。
