Assessment of postexercise muscle soreness by electromyography and mechanomyography

Mechanomyography (MMG) and electromyography (EMG) recordings from the first dorsal interosseous muscle of the hand were compared for pre-exercise and immediately after, 24-hour, and 48-hour postexercise muscle soreness. Thirteen healthy male subjects performed progressively increasing number of eccentric contractions from bout 1 (10.34 +/- 1.96) to bout 6 (27.46 +/- 5.01) (P < .03) with 116% maximum voluntary contraction (MVC) for provocation of postexercise muscle soreness. Increased areas of pain, reduced pressure pain threshold, reduced MVC, and reduced range of motion were present immediately after as compared with pre-exercise (P < .05). During intense eccentric exercise, root mean squared amplitude values of MMG increased progressively from bout 1 to bout 6, but EMG root mean squared amplitude decreased as the muscle fatigued (P < .05). Time course changes of MMG and EMG root mean squared amplitude values during single concentric, isometric, and eccentric contractions at 0%, 25%, 50%, 75%, and 100% MVC weights were measured in relation to postexercise muscle soreness. The EMG root mean squared amplitude values showed insignificant changes for concentric, isometric, and eccentric contractions between pre-exercise, immediately after, 24 hours, and 48 hours. MMG root mean squared amplitude values increased during concentric, isometric, and eccentric contractions at immediately after as compared to pre-exercise, 24 hours, and 48 hours. At immediately after, 24 hours, and 48 hours the maximum EMG root mean squared amplitude values were achieved at lower MVC levels as compared with pre-exercise (P < .05). MMG root mean squared amplitude findings suggest changes in viscoelastic properties resulting in significant mechanical muscle vibrations after intense eccentric exercise. This may suggest a role of stimulation of mechanosensitive nociceptors in relation to postexercise muscle soreness. It is concluded that simultaneous recordings of MMG and EMG may serve as an appropriate means of studying the relationship between electrical and mechanical muscle activity occurring with postexercise muscle soreness.