Range of motion can also be used to describe the existing amount of motion around a joint. For example, if a cyclist who rides 100 miles or more per week doesn't stretch regularly, he or she might experience limited motion at the hip joint. The term 'range of motion' could be used to refer to this measurement.
Another example would be a person who sits at the computer all day. Such a person is likely to have tight muscles at the front of the shoulder joint, and overstretched muscles in the upper back. This imbalance in muscle tone will probably alter that person's range of motion at the shoulder.
Range of motion is expressed in degrees of joint angle or circumference (depending upon what type of joint is being measured). Each joint has an established normal range, based on what that joint does and where the two bones comprising it can move no more. In other words, the normal range of movement is determined by the architecture of the bones and the soft tissues that surround the joint to hold it together.
Range of motion is very related to flexibility. It is measured with a device called the goniometer.