Since bone is a live tissue, it responds to the environment just as the other live tissues do. A good example is the strong and large muscles of a weight lifter. Bones respond to the stresses placed upon them, which occur in the direction of their long axis (the direction muscles pull on them). When the normal stresses placed upon bones by normal physical activity are removed, bone will loose density. This is best illustrated in patients with spinal cord injuries who can have a very significant loss of bone density. The opposite is true as well since athletes have stronger bones than normal sedentary adults.

The positive effect that exercise has on bone density (BMD) (and therefore the risk of osteoporosis) is greatest in adults who have been sedentary and begin to exercise. A very active individual, on the other hand, will typically see less of a positive effect on BMD if they begin to exercise aggressively. Weight bearing exercises such as walking, running, jogging, and dancing have been the exercises that doctors have recommended for many years. It has become clear that those activities which include higher impact have a greater benefit to the bones. Therefore, although swimming is a great exercise for cardiovascular fitness, walking or jogging will usually provide better bone health. For older individuals, a regular program of brisk walking may assist in bone maintenance. Weight lifting may also be helpful even though it is not a high impact exercise, with some of the benefit likely coming from increased leg strength which may help prevent falls and the hip fractures with frequently accompany them.

Some studies have shown that bone mass will decrease when exercise training stops. Therefore, for an exercise program to help maintain healthy bones it needs to be continued. It is important for you to consult your doctor prior to beginning any exercise program. He/she will be able to prescribe the right exercises for you.