A contracture defines a lasting state of contraction of a muscle in the absence of voluntary stimulation. A muscle spasm is a type of cramp which lasts longer and primarily affects athletes. Most often, it occurs in one of the lower thigh muscles, frequently the calves, or the muscles of the back and neck. Contracture is often painful and impedes the function of the afflicted zone. Rest, massage, warmth and analgesics generally provide relief from the pain. Drugs that induce muscle relaxation may also be used temporarily: these are called myorelaxants.