Effect of short-time vibration exposure on work movements with carpenters' hand tools

• The purpose of this study was to analyze the effect of ac ute vibration exposure on manual performance. Ten experienced healthy carpenters performed three standardized common tasks (nailing, sawing, screwing). EMG activity was recorded from six arm-shoulder muscles/muscle group using surface electrodes, and the performances were video-filmed. The subjects also reted their exertions. After ten minutes of standardized vibration exposure (50 Hz, 20 m/s2) the tasks were repeated. The number of work movements and the time taken for each task were recorded. In addition the quality of the work performed after the first and second trials was compared. Changes in muscle activity were mainly increased activity in trapezius. The most active muscles, with EMG mean values exceeding 10% EMGmax, were trapezius (mean values 9-21% EMGmax, infraspinatus (mean 6-18% EMGmax) and flexor digitorum (mean 15-21% EMGmax). Only rating perceived exertion while nailing was higher after vibration. Vibration exposure seemed to be very individually perceived. Short-time exposure did not seem to influence the performance of well-known tasks.

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