Heavily used joints such as knees and ankles can become less flexible due to cartilage and ligament calcification. The bones in the hands, knees and feet may suffer erosion type damage due to overuse. The use of damaged joints, already limited by decreased flexibility, results in pain and reduced range of motion. The outcome from experiencing stiff and painful joints is a continual decline in the types of movement that cause pain, leading to even more stiffness. When stiffness of joints limits their use, muscles and bones are not stressed enough to maintain proper function.
Muscles become weaker and bones become brittle.
Loss of flexibility from weakened muscles and degenerated joints can usually be reversed with appropriate exercise.