Range of Motion Explained

When you lift your arm, bend your knee, or twist your torso, your body is moving through its range of motion (ROM) the extent to which a joint can move in different directions. Whether you’re recovering from an injury, working on flexibility, or simply curious about how your body functions, understanding ROM can help you protect your joints and improve mobility.

How Range of Motion Is Measured

Healthcare providers often assess ROM during physical therapy sessions or after an injury to see how much movement is possible in a joint.

• Goniometer: A simple tool with two arms that measures the angle of a joint.

• Measuring tape: Used for the spine, such as in the Schober test, which tracks how much your back bends forward.

These tools provide accurate readings to compare your movement with typical ranges and identify restrictions.

The Three Types of Range of Motion

Not all ROM is the same. Physical therapists typically assess three kinds:

• Passive ROM (PROM): Someone else moves your joint for you while your muscles stay relaxed. For example, after knee surgery, a therapist may gently bend and straighten your leg.

• Active-assistive ROM (AAROM): You move the joint with some help from another person or device. This often comes into play during early rehabilitation after surgery, such as rotator cuff repair.

• Active ROM (AROM): You move the joint entirely on your own using your muscles, such as bending your elbow or lifting your arm overhead.

Active ROM is usually slightly less than passive ROM because muscles have to work against resistance.

What Limits Range of Motion?

Several medical conditions, injuries, and lifestyle factors can restrict how freely your joints move. Common causes include:

• Arthritis: Both osteoarthritis (wear-and-tear) and rheumatoid arthritis (autoimmune) can stiffen joints.

• Joint injuries: Fractures, dislocations, or torn tendons like a rotator cuff tear.

• Inflammatory conditions: Bursitis or tendinitis around a joint.

• Neurological conditions: Cerebral palsy or congenital torticollis.

• Spinal conditions: Ankylosing spondylitis, which fuses vertebrae and reduces spinal flexibility.

• Lifestyle factors: Obesity can physically limit movement due to added tissue around joints.

Why It Matters for Recovery and Mobility

Tracking ROM gives healthcare providers insight into how well a joint is healing and whether therapy is working. For example:

• After surgery, passive ROM helps keep joints from stiffening.

• During rehab, active-assistive ROM supports healing muscles without overloading them.

• Eventually, active ROM helps restore independence and strength.

A physical therapist can design exercises and stretches tailored to your ROM, gradually increasing flexibility and reducing pain.

Key Takeaway

Range of motion describes how far your joints can move in different directions, whether independently or with assistance. It’s an important marker for joint health, injury recovery, and overall mobility. If pain, stiffness, or an injury limits your movement, consult a physical therapist or doctor to determine the best approach for regaining flexibility.

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