Range of motion is a term that refers to the extent to which a joint or group of muscles can be flexed or extended. By studying people in a wide variety of physical conditions, researchers have determined normal measurements for all the major joints and muscle groups, and these measurements can be used to assess a patient. Many core exercises are aimed at increasing this range, and people can also embark on specific exercises that are designed to promote an increased ability to flex and extend various joints. This concept is closely related to flexibility.
In a simple example, imagine folding someone's elbow as much as possible into a flexed position, and then straightening it out into a fully extended position. The variation between the flexed and extended positions indicates that person's range of motion in the elbow joint, typically expressed in degrees. In the case of the elbow, the normal range extends from 0 to 145 degrees.
When determining how freely a patient can move particular joints and muscles, a doctor or physical therapist will perform both passive and active measurements. In a passive measurement, someone else gently flexes and extends the patient's joint, while active measurements require the patient to move the joint or muscle group, sometimes working against resistance such as a weight. Passive measurements are often higher, as the medical professional may be able to push the body more than the patient can.
A huge assortment of things can influence range of motion, including disease, injury, trauma, physical activity, and other events. People with a limited range may experience frustration because they cannot engage in many common tasks, and they can be at increased risk of injury and other medical problems as a result of their stiffer joints and muscle groups. For example, a woman who cannot fully bend her knee joint may be prone to falls or injuries to muscle groups in the leg.
Exercises such as yoga and Pilates, which are used to supplement regular exercise routines, usually increase range of motion by developing strong joints and muscle groups, and pushing muscles so that they can lengthen. Specific exercises can also be used to improve the ability of various joints and muscle groups to fully flex and contract, and these exercises are often part of a physical therapy regimen to help someone recover from a medical problem.