Premovement silent period in fast movement initiation.

Premovement inhibitory processes were studied in human subjects performing ballistic elbow movements in a self-paced or reaction time situation. The experiments were designed to test the hypothesis that there is an interdependence between a preparatory disfacilitatory process at the motoneurone level and an impending phasic motoneurone activation. The results indicate that in ballistic movements there is a positive relation between extent of premovement depression of tonic activity and subsequent phasic innervation. The results suggest that in high speed movements where a maximal number of motor units have to be recruited, those motoneurones which are already tonically active have to be released from tonic activity for optimal synchrony.