As an exercise treatment, physical therapy is for patients who are restricted in their range of motion or flexibility. Rehabilitation involves teaching patients to use their own muscles to improve flexibility and range of motion while also increasing muscular strength and endurance. Active physical therapy techniques like ultrasound and hot/cold packs are often used in conjunction with modalities (passive physical therapy) to treat pain and swelling. A deep-tissue massage or traction therapy can also help relieve pain. Patients may be taught to use assistive and adaptive devices (such as crutches) and exercises to do at home by therapists if that is necessary to speed up the recovery.