Reaction time of motor units in biceps and triceps

Abstract

Human subjects can gain sufficient control over the firing of a single spike from motor units in biceps and triceps to perform effectively in a reaction time experiment. A comparison of reaction time latencies of the voluntarily produced single motor unit discharges in biceps and triceps reveals stable differences. Triceps units usually have shorter reaction time latencies than do biceps units. Variability of single-unit reaction time is less for triceps units than for biceps units. Comparison with gross EMG performance shows consistently greater unit reaction time latency regardless of muscle of origin. Intermittent loss of control over motor unit occurs in the reaction time task.