What Is Range of Motion?

Range of motion (ROM) is a term used to describe how far you can move a joint or muscle in various directions. It is used to measure how much you can move a joint on your own (active ROM) or with the assistance of someone else (passive ROM).

While the range of motion of a joint can vary from one person to the next, there are expected (normal) values that a healthcare provider will use to determine if your movement is in any way restricted. Range of motion is usually assessed during a physical therapy evaluation or when a joint has been injured.

This article describes how range of motion is measured and how active and passive ROM are used in the diagnosis and treatment of joint problems. It also lists the different conditions that can affect the range of motion of different joints.

Doctor measuring person's knee range of motion
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How Range of Motion Is Measured

Range of motion is measured using a device called a goniometer. A goniometer is a simple handheld device with two arms that measures angles. By lining up the arms of the device with a joint, a physical therapist can get an exact measurement of how much you can move a joint.

A goniometer is suitable for most joints with the exception of the back and spine. For this, a physical therapist would use a measuring tape to see how far spinal bones move when going from a standing to a forward-bending position. The procedure, known as the Schober test, is used to diagnose and evaluate spinal conditions like ankylosing spondylitis.

There are three types of ROM that are measured as part of physical therapy evaluation. They are known as passive ROM (PROM), active-assistive ROM (AAROM), and active ROM (AROM).

Passive Range of Motion

Passive ROM occurs around a joint if you are not using your muscles to move. Someone else, like your physical therapist, manually moves your body while you relax. A machine may also be used to provide passive ROM.

For example, after knee replacement surgery, you may not be able to use your muscles to move the knee. Your physical therapist may bend and straighten your knee for you, passively moving your leg. Occasionally, a device called continuous passive motion (CPM) is used to provide passive ROM.

Passive ROM is usually used during the initial healing phase after surgery or injury. If paralysis prevents your body from moving normally, passive ROM may also be used to prevent contractures or skin pressure ulcers.

Active-Assistive Range of Motion

Active-assistive ROM occurs when you are able to move your injured body part, but you may require some help to move to ensure further injury or damage does not occur. The assistance that helps move your body can come from you or from another person. It may also come from a mechanical device or machine.

An example of AAROM is after shoulder rotator cuff surgery. You may be allowed to move your arm, but another person may assist your arm during the motion to help limit the amount of stress that may occur.

Active-assistive ROM is typically used after injury or surgery when some healing has occurred and your muscle can contract, but protection is still required to prevent damage to your healing body part.

Active Range of Motion

Active ROM occurs when you use your muscles to help move your body part. This requires no other person or device to help you move.

When bending your elbow, for example, you need to simultaneously contract (shorten) your biceps while relaxing your tricep muscles. Active ROM measures your ability to do this on your own.

Active range of motion is usually less than passive range of motion.

Active ROM is used when you are able to start moving independently after injury or surgery, and little or no protection from further injury is needed. Strengthening exercises are a form of active ROM.

Causes of Limited Range of Motion

There are conditions that can restrict (limit) the range of motion of a joint. These include:


Range of motion is the extent that a joint can move within the expected (normal) range of values. ROM can be measured using a handheld device called a goniometer and, for the back and spine, a measuring tape.

The ROM value can help diagnose or characterize a joint condition as well as track your progress during rehabilitation from surgery or an injury. The evaluation may involve the measurement of a joint's active ROM (done without assistance), passive ROM (done with assistance), and active-assisted ROM (done with partial assistance).

A Word From Verywell

Understanding what range of motion is and how it is used in physical therapy can help you become better informed about your course of physical therapy and have a positive physical therapy experience.

Be sure to speak with your physical therapist or doctor to understand what type of range of motion is necessary if you are injured or have had surgery. Working towards normal ROM can help ensure a safe and rapid return to optimum functional mobility.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Bandy WD, Sanders, B. Therapeutic Exercise for Physical Therapist Assistants. Philadelphia, PA: Lippincott, Williams & Wilkins; 2008.

Additional Reading
  • Kisner, C., & Colby, L. A. (1996). Therapeutic exercise: Foundations and techniques. (3 ed.). Philadelphia: FA Davis.

By Brett Sears, PT
Brett Sears, PT, MDT, is a physical therapist with over 20 years of experience in orthopedic and hospital-based therapy.