Therapeutic exercise is the scientific supervision of bodily movement, with or without apparatus, for the distinct purpose of restoring normal function to diseased or injured tissues. There are two types of therapeutic exercise—passive and active.
Passive exercise is that form of bodily movement which is carried through by the operator without the assistance or resistance of the patient. Mennell1 uses the term relaxed movement. Passive movement should be administered with great care, with the arm or leg to be manipulated rightly held and the patient completely relaxed and pumping movement avoided. The occurrence of a muscle spasm is a danger signal. If such a spasm occurs the operator should stop immediately. It should be remembered that a slight tightening of the muscles precedes pain. Therefore, to secure the best results all movements should be well within the limit at which pain occurs. It should be kept constantly in mind
COULTER JS, MOLANDER CO. TECHNIC OF THERAPEUTIC EXERCISE. JAMA. 1930;95(18):1342–1347. doi:10.1001/jama.1930.27210180002012