Old people's bones don't move easily. Officially, they are stiff and lack exercise. Therefore, the old-age fitness ball can make joints move and eliminate pain. People's upper limbs have shoulder joints, elbow joints and hand joints. With the increase of age, human joints and other tissues can undergo degenerative changes to varying degrees. Generally, after the age of 50, the joints such as hands, elbows and shoulders begin to be inflexible, and some will still be painful. Old people often exercise fitness balls, which can prevent joint aging and make fingers, elbows and shoulder joints flex and stretch, and have an effect on arthritis.