Spadm explaination. Involuntary sustained contraction of muscle without relaxation phase of skeletal muscle our motion is a combination of contraction and relaxation of groups of muscle no contrtactiona paralysis no relaxation spasm paralysis of a different sort.
Painful. Your muscles "spasm" when either the signal to them is interrupted; they are asked to do something they do not want to do, or they are overworked. It is their way of telling you that they need to rest; and they need attention.