EFFECTS OF BATHING ON TRAPEZIUS MUSCLE FATIGUE INDUCED BY TYPEWRITING TASK

Abstract

The effect of bathing on recovery of muscle fatigue in the trapezius was examined in 6 healthy male adults. The subjects performed four sets of 25-min typewriting tasks and then rested on a chair for one hour. The development and recovery of muscle fatigue in the upper trapezius was periodically monitored with an electromyogram (EMG) in parallel with subjective muscle fatigue, surface and core temperatures, and near-infrared spectroscopy tests. The surface EMG was recorded during a 15-sec contraction at 30% maximum voluntary contraction to evaluate the muscle fatigue. During typewriting, muscle fiber conduction velocity and median frequency significantly decreased in parallel with an increase in subjective muscle fatigue (P<0.0001, P<0.0001). Bathing did not affect the recovery of physiological muscle fatigue, while the recovery of subjective muscle fatigue was accelerated markedly by 10-min hot water bathing. These findings suggest that utilizing hot water bathing could primarily contribute to the recovery of subjective muscle fatigue. The recovery of physiological muscle fatigue needs more time than the recovery of subjective fatigue feeling.