Silent period is transient and relative or absolute pause of discharges of muscle action potential in a sustained contracting muscle. SP can be produced by orthodromic motor or antidromic sensory volleys by stimulating a mixt nerve or a sensory nerve. It is considered that a transient muscle spindle pause or Renshaw inhibition is the cause of SP. However, suprasegmental motor control mechanisms might be involved in SP.

In this study, SP is studied in 11 healty volunteer in both APB muscles by means of median nerve stimulation and transcortical magnetic stimulation(TCMS). SP was found 111 msec, SD:16.06 (81-139 msec) by median nerve stimulation and 168 msec, SD:82.4 (66-344 msec) by TCMS. LLR was also considered in median nerve stimulation and found 53 msec, SD:5.97 (46-65 msec).