To move the legs, the muscles contract and pull on the bones, stressing them further. Non-weight bearing activities only put muscular stress on your bones. In swimming, for example, the buoyant force of the water negates most of the force of gravity, thus, only the muscular stress needed to move the arms and legs stress the bone. Many people have assumed that an exercise such as swimming would not increase bone density because of the lack of weight bearing and limited use of the large leg muscles. However, recent findings suggest that swimming can also increase bone density.
Swimming requires muscle movement which stresses the bones and promotes growth.
However, the gains are not as great as weight bearing exercises. The benefits of swimming in maintaining or increasing bone mass is very important to those who already have osteoporosis. For them, swimming and water aerobics can be a gentle, non-traumatic way to maintain or increase their bone mass. Increasing your activity levels Before you add an exercise program to strengthen your bones, think of ways to add more physical activity to your daily life. Take the stairs instead of the elevator.