Range of motion
Range of motion 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
Mechanical engineering
Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...

 fields. For example, a volume knob (a rotary
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...

 fader) may have a 300° range of travel from the "off" or mute
Mute may refer to:* Muteness, a speech disorder in which a person lacks the ability to speak* Mute, a silent letter in phonology* Mute , an upcoming sequel to the movie Moon...

d (fully attenuated) position at lower left, going clockwise
Circular motion can occur in two possible directions. A clockwise motion is one that proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back to the top...

 to its maximum
Full scale
In electronics and signal processing, full scale or full code represents the maximum amplitude a system can present.-Electronics and signal processing:...

-loudness position at lower right.

As used in the biomedical and weightlifting
Powerlifting is a strength sport. It resembles the sport of Olympic weightlifting, as both disciplines involve lifting weights in three attempts. Powerlifting evolved from a sport known as 'odd lifts' which followed the same three attempt format but used a wide variety of events akin to Strongman...

 communities, range of motion refers to the distance and direction a joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

 can move between the flexed position and the extended position. The act of attempting to increase this distance through therapeutic exercises (range of motion therapy—stretching
Stretching is a form of physical exercise in which a specific skeletal muscle is deliberately elongated, often by abduction from the torso, in order to improve the muscle's felt elasticity and reaffirm comfortable muscle tone. The result is a feeling of increased muscle control, flexibility and...

 from flexion to extension for physiological gain) is also sometimes called range of motion.

Measuring range of motion

Each specific joint has a normal range of motion that is expressed in degrees.

Devices to measure range of motion in the joints of the body include the goniometer
A goniometer is an instrument that either measures an angle or allows an object to be rotated to a precise angular position. The term goniometry is derived from two Greek words, gōnia, meaning angle, and metron, meaning measure....

 and inclinometer
An inclinometer or clinometer is an instrument for measuring angles of slope , elevation or depression of an object with respect to gravity...

 which use a stationary arm, protractor, fulcrum, and movement arm to measure angle from axis of the joint.

As measurement results will vary by the degree of resistance, two levels of range of motion results are recorded in most cases.

Limited range of motion

Limited range of motion refers to a joint that has a reduction in its ability to move. The reduced motion may be a mechanical problem with the specific joint or it may be caused by injury or diseases such as osteoarthritis, rheumatoid arthritis, or other types of arthritis. Pain, swelling, and stiffness associated with arthritis can limit the range of motion of a particular joint and impair function and the ability to perform usual daily activities.

Range of motion exercises

Physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...

can help to improve joint function by focusing on range of motion exercises. The goal of these exercises is to gently increase range of motion while decreasing pain, swelling, and stiffness. There are three types of range of motion exercises:
  • Passive range of motion (or PROM) - Therapist or equipment moves the joint through the range of motion with no effort from the patient.
  • Active assistive range of motion (or AAROM) - Patient uses the muscles surrounding the joint to perform the exercise but requires some help from the therapist or equipment (such as a strap).
  • Active range of motion (or AROM) - Patient performs the exercise to move the joint without any assistance to the muscles surrounding the joint.
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