FIG. 4.

Active muscles and clonus duration. The number of muscles active during clonus as a function of clonus duration (r=0.76, p<0.01, n=47 spasms, 12 subjects). A muscle was deemed “active” if it produced EMG for at least 10% of clonus duration around the middle of the spasm (45–55% of individual spasm duration). Active muscles are listed (right). Two active muscles included triceps surae and ipsilateral tibialis anterior (TS+TA). Activation of a third muscle (hamstrings, + HM), a fourth muscle (vastus lateralis, + VL), and five or six muscles (one or two contralateral muscles, + CL-SL±TA) corresponded to three, four, five, or six muscles, respectively.