Mischi Massimo, Cardinale Marco
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
Med Sci Sports Exerc. 2009 Mar;41(3):645-53. doi: 10.1249/MSS.0b013e31818a8a69.
The aim of this study was to evaluate activation and coactivation of biceps and triceps muscles during isometric exercise performed with and without superimposing a vibration stimulation.
Twelve healthy volunteers (age = 22.7 +/- 2.6 yr) participated in this study. The subjects performed five trials of isometric elbow flexion and five trials of elbow extension with increasing levels of force in two conditions: vibration (V) and normal loading (C). V stimulation was characterized by a frequency of 28 Hz. Surface EMG activity of biceps and triceps muscles was simultaneously measured by bipolar surface electromyography and assessed by the estimation of the root mean square (RMS) of the electrical recordings over a fixed 5-s interval. Frequency analysis was adopted to estimate the RMS related to muscle activation and to exclude the harmonics generated by movement artifacts due to V.
The analysis of the recordings revealed a significant EMG RMS increase when V was applied. On average, the EMG RMS of biceps and triceps during elbow flexion was, respectively, 26.1% (P < 0.05) and 18.2% (P = 0.15) higher than C. During elbow extension, the EMG RMS of biceps and triceps was 77.2% and 45.2% (P < 0.05) higher than C, respectively. The coactivation was assessed as the ratio between the activation of antagonist and agonist muscles during arm flexion and extension tasks. The results revealed an increase of coactivation during V exercise, especially for lighter loads.
This study shows that V exercise at 28 Hz produces an increase of the activation and the coactivation of biceps and triceps. This exercise modality seems therefore suitable for various applications.
本研究旨在评估在进行等长运动时，有无叠加振动刺激情况下肱二头肌和肱三头肌的激活及共同激活情况。
12名健康志愿者（年龄 = 22.7±2.6岁）参与了本研究。受试者在两种条件下进行了五次等长屈肘试验和五次等长伸肘试验，力的水平逐渐增加：振动（V）和正常负荷（C）。V刺激的频率为28Hz。通过双极表面肌电图同时测量肱二头肌和肱三头肌的表面肌电活动，并通过估计固定5秒间隔内电记录的均方根（RMS）进行评估。采用频率分析来估计与肌肉激活相关的RMS，并排除由V引起的运动伪影产生的谐波。
记录分析显示，施加V时肌电RMS显著增加。平均而言，屈肘时肱二头肌和肱三头肌的肌电RMS分别比C高26.1%（P < 0.05）和18.2%（P = 0.15）。伸肘时，肱二头肌和肱三头肌的肌电RMS分别比C高77.2%和45.2%（P < 0.05）。共同激活被评估为手臂屈伸任务中拮抗肌和主动肌激活之间的比率。结果显示，在V运动期间共同激活增加，尤其是对于较轻负荷。
本研究表明，28Hz的V运动可使肱二头肌和肱三头肌的激活及共同激活增加。因此，这种运动方式似乎适用于各种应用。
