Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles

The aim of this study was to evaluate the influence of vibration on the mec hanical properties of arm flexors. A group of 12 international level boxers , all members of the Italian national team, voluntarily participated in the experiment: all were engaged in regular boxing training. At the beginning of the study they were tested whilst performing forearm flexion with an ext ra load equal to 5% of the subjects' body mass. Following this, one arm was given the experimental treatment (E; mechanical vibration) and the other w as the control(no treatment). The E treatment consisted of five repetitions lasting 1-min each of mechanical vibration applied during arm flexion in i sometric conditions with 1 mill rest between them. Further tests were perfo rmed 5 min immediately after the treatment on both limbs. The results showe d statistically significant enhancement of the average power in the arm tre ated with vibrations. The root mean square electromyogram (EMG,,) had not c hanged following the treatment but, when divided by mechanical power, (P) a s an index of neural efficiency, it showed statistically significant increa ses. It was concluded that mechanical vibrations enhanced muscle P and decr eased the related EMG/P relationship in elite athletes. Moreover. the analy sis of EMG(rms) recorded before the treatment and during the treatment itse lf showed an enormous increase in neural activity during vibration up to mo re than twice the baseline values. This would indicate that this typo of tr eatment is able to stimulate the neuromuscular system more than other treat ments used to improve neuromuscular properties.