Effects of Inactivity and Exercise on Bone

Abstract
In brief: Research has shown that bone tissue responds to the forces of gravity and muscle contraction, and thus, weight-bearing exercise is useful in preventing or reversing age-related osteopenia that often results in fractures. For persons with very low fitness levels or with preexisting fractures, non- weight-bearing or low-impact exercise may help strengthen or protect bone by increasing the muscle strength. However, the specific intensity, duration, and frequency of exercise necessary to enhance bone have not yet been delineated.