Pincivero Danny M, Polen Rachael R, Byrd Brittany N
Department of Kinesiology, University of Guelph-Humber, Canada.
Department of Kinesiology, The University of Toledo, United States.
J Electromyogr Kinesiol. 2019 Feb;44:101-107. doi: 10.1016/j.jelekin.2018.12.002. Epub 2018 Dec 8.
Agonist muscle contraction mode and intensity effects on antagonist co-activation was examined between men and women.
Fifteen healthy young men (mean ± standard deviation age = 24.9 ± 4.2 years, body mass index = 23.17 ± 2.34) and 15 women (mean ± standard deviation age = 21.8 ± 2.3 years, body mass index = 24.16 ± 2.91) performed five isokinetic concentric and eccentric maximal-effort elbow flexor/extensor contractions to establish their peak torque. Participants then performed a series of randomly ordered sub-maximal (10-90% of peak torque, 10% increments) elbow flexor contractions over two separate experimental sessions. All sub-maximal elbow flexor contractions were concentric during the first session, while eccentric contractions were performed during the second session. Antagonist co-activation was quantified as the elbow extensor surface electromyogram (EMG) magnitude during all flexor contractions, normalized to its' respective MVC level, when acting as an agonist.
The results demonstrated significant contraction intensity (p < 0.001), gender (p < 0.001) and contraction mode (p < 0.001) main effects, indicating that co-activation: (1) increased from 10-90% MVC (5.40% to 12.01%), (2) was greater in women than men (12.06% vs 3.68%), and (3) was greater during concentric than eccentric contractions (9.82% vs 5.92%), without correcting for skinfold thickness. A significant gender by contraction intensity interaction demonstrated that women displayed greater increases in co-activation, as compared to the men, across 10-90% MVC. Following correction for skinfold thickness, the gender difference was not found to be statistically significant.
The major findings demonstrated that antagonist muscle co-activation demonstrated a dependency on contraction intensity and mode; however, a gender difference was not observed when corrected for skinfold thickness.
研究了男性和女性之间，主动肌收缩模式和强度对拮抗肌共激活的影响。
15名健康年轻男性（平均±标准差年龄=24.9±4.2岁，体重指数=23.17±2.34）和15名女性（平均±标准差年龄=21.8±2.3岁，体重指数=24.16±2.91）进行五次等速向心和离心最大用力的肘屈肌/伸肌收缩，以确定其峰值扭矩。参与者随后在两个独立的实验环节中进行了一系列随机排序的次最大（峰值扭矩的10%-90%，以10%递增）肘屈肌收缩。在第一个环节中，所有次最大肘屈肌收缩均为向心收缩，而在第二个环节中进行离心收缩。拮抗肌共激活通过所有屈肌收缩期间的肘伸肌表面肌电图（EMG）幅度进行量化，并在作为主动肌时将其归一化至各自的最大自主收缩（MVC）水平。
结果显示出显著的收缩强度（p<0.001）、性别（p<0.001）和收缩模式（p<0.001）主效应，表明共激活：（1）从10%-90%MVC增加（5.40%至12.01%），（2）女性高于男性（12.06%对3.68%），（3）向心收缩时高于离心收缩（9.82%对5.92%），未校正皮褶厚度。收缩强度与性别之间的显著交互作用表明，在10%-90%MVC范围内，女性的共激活增加幅度大于男性。校正皮褶厚度后，未发现性别差异具有统计学意义。
主要研究结果表明，拮抗肌共激活表现出对收缩强度和模式的依赖性；然而，校正皮褶厚度后未观察到性别差异。
