Pre-motor and motor reaction time differences associated with stretching of the hamstring muscles

Pre-motor and motor RT scores were obtained from 24 male Ss using a knee flexion task. It was predicted that an increased arousal state due to proprioceptive feedback from stretched hamstring muscles would shorten pre-motor RT while motor RT would shorten because of changes in muscle tension development due to changes in the series elastic and/or contractile components of the muscle tissue. A finger RT task was also included in order to determine whether other factors not related to changes in the stretch of the hamstring muscles were operative. Motor RT decreased with increased muscle stretch and constituted 46% of leg RT. Pre-motor RT as well as finger RT increased rather than decreased with increased muscle stretch. No relationship was found between pre-motor and motor RT indicating that lags in CNS processing are independent of lags associated with the rate of muscular tension development.