Range of motion

Range of motion or (ROM), is the distance (linear or angular) that a movable object may normally travel while properly attached to another object. It is also called range of travel, particularly when talking about mechanical devices and in mechanical engineering fields. For example, a volume knob (a rotary fader) may have a 300° range of travel from the "off" or muted (fully attenuated) position at lower left, going clockwise to its maximum-loudness position at lower right.

As used in the biomedical and weightlifting communities, it is the measurement of the achievable distance between the flexed position and the extended position of a particular joint or muscle group. The act of attempting to increase this distance through therapeutic exercises (range-of-motion therapy—stretching from flexion to extension for physiological gain) is also sometimes called range of motion.

A person who uses a wheelchair may improve the range of motion in their spine, hips, knees and ankles by using a standing frame, if possible. It is necessary that the gain in joint range be accompanied by the gain in function of the muscles which control that particular range of motion.

Measuring range of motion

As measurement results will vary by the degree of resistance, two levels of range-of-motion results are recorded in most cases. Passive range of motion, where another person, such as a caregiver or therapist, moves the joint. Active (or manual) range of motion, where the individual moves the joint themselves. Free active movements - the only resistance is the weight of the limb or body and the force of gravity that it fights. Free active movements are generally performed to increase and retain strength and flexibility. Resisted active movements - for resistance, weights are added to the limb, a physician, therapist or another person applies pressure, or a stretch band is used. Resisted active movement exercises are used to increase strength and endurance.

A goniometer is used to measure ROM. The segments of a goniometer include the stationary arm, protractor, fulcrum and movement arm.

An inclinometer is used to measure ROM. It typically uses 2 sensors, one in a reference position, and another attached to the moving part being examined. Movements of the body segments takes place as muscles or external forces moves bones. Bones with respect to each other at the connecting joint, as well as the integrity and flexibility of the soft tissues that pass over the joints, affects the amount of motion that can occur between any two bones. The full motion possible is called the range of motion(ROM). When moving of the segment trough its range of motion, all structures in the region is affect; muscles, joint surfaces, capsules ligaments, fascia, vessels and nerves.

See also

• Joint locking (symptom)

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