At your joints, your bones move around each other. The shape and size of the joints and the flexibility of the muscles, ligaments, blood vessels, and nerves, affect how much movement can occur between two bones. The full amount of motion that can occur at a joint is called the range of motion (ROM).

If the ROM at a joint is less than normal there may be certain functional activities that you cannot perform. For example, if your knee has a decreased ROM you may not have full extension causing improper gait and walking with a limp.

In order to maintain normal ROM, joints must be moved through their available range quite often. If you are immobile due to an injury or illness, you may lose some of your joints' normal ROM. Physical therapists help to prevent this from happening by helping patients to continue to move all of their joints. These are called range of motion exercises.