Sontag Stephanie A, Sterczala Adam J, Miller Jonathan D, Deckert Jake A, Olmos Alex A, Parra Mandy E, Dimmick Hannah L, Gallagher Philip M, Fry Andrew C, Herda Trent J, Trevino Michael A
Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK, United States of America.
Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburg, Pittsburgh, PA, United States of America.
Med Eng Phys. 2023 Jan;111:103946. doi: 10.1016/j.medengphy.2022.103946. Epub 2022 Dec 23.
This study examined relationships between percent myosin heavy chain (%MHC) expression and mechanomyographic amplitude (MMG). Fifteen females (age ± SD=21.3 ± 5.3 yrs) completed isometric trapezoidal contractions at 30% and 70% maximal voluntary contraction (MVC). MMG was recorded from the vastus lateralis (VL). Participants gave a muscle biopsy of the VL post-testing. MMG-torque relationships during the linearly varying segments were log-transformed and linear regressions were applied to calculate b terms (slopes). For the steady torque segment, MMG was averaged. Correlations were performed for type I%MHC with the MMG variables. Multiple regression was utilized to examine prediction equations for type I%MHC. Type I%MHC was significantly correlated with the b terms during the increasing segment of the 70% MVC (p = 0.003; r = -0.718), and MMG during steady torque at 30% (p = 0.008; r = -0.652) and 70% MVC (p = 0.040; r = -0.535). Type I%MHC reduced the linearity of the MMG-torque relationship during the high-intensity linearly increasing segment, and MMG at a low- and high-intensity steady torque. A combination of MMG variables estimated type I%MHC expression with 81.2% accuracy. MMG recorded during a low- and high-intensity isometric trapezoidal contraction may offer a simple, noninvasive test for estimating type I%MHC expression of the VL in sedentary females.
本研究考察了肌球蛋白重链百分比（%MHC）表达与肌机械图振幅（MMG）之间的关系。15名女性（年龄±标准差=21.3±5.3岁）以最大自主收缩（MVC）的30%和70%完成等长梯形收缩。从股外侧肌（VL）记录MMG。参与者在测试后进行了VL的肌肉活检。对线性变化段的MMG-扭矩关系进行对数转换，并应用线性回归计算b项（斜率）。对于稳定扭矩段，对MMG进行平均。对I型%MHC与MMG变量进行相关性分析。利用多元回归检验I型%MHC的预测方程。I型%MHC与70%MVC增加段的b项显著相关（p = 0.003；r = -0.718），与30%（p = 0.008；r = -0.652）和70%MVC稳定扭矩时的MMG显著相关（p = 0.040；r = -0.535）。I型%MHC降低了高强度线性增加段以及低强度和高强度稳定扭矩时MMG-扭矩关系的线性度。MMG变量的组合估计I型%MHC表达的准确率为81.2%。在低强度和高强度等长梯形收缩期间记录的MMG可能为估计久坐女性VL的I型%MHC表达提供一种简单、无创的测试方法。
