Range of motion tests may also be called flexibility tests. They are used to measure how well you can move a joint. Some joints like the thumb and shoulder have a wide range of motion, almost a complete circle. Other joints like the knee are like hinges and have a more limited range of motion. Range of motion tests may be active or passive. In active tests, you do all the movement. In passive tests, the doctor will hold the extremity and move it. He or she may also hold the next joint steady to isolate the movement of the joint being tested. For example, while you are seated, the doctor may hold your lower leg still while moving your heel in and out. (See Flexibility Tests.)