Muscular contractions (6)
I believe the answer is:
spasms
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">muscular contractions</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for spasms that I've seen before include "Cramps or contractions" , "attacks" , "Involuntary convulsive movements" , "Convulsions or cramps" , "sudden bursts of activity" .)