How does physical activity affect bone mass?

Bone mass is subject to mechanical factors; when bone is stressed regularly through movement or physical activity, it responds by increasing mineral density. When bone is not stressed regularly, it loses density. Thus, athletes have more bone mass than sedentary individuals, and the most bone mass in those areas most stressed (the bones in the preferred arm of a tennis player will show more density).

Research shows that physical activity, including and especially weight-bearing activity like walking, jogging, and upright weight-lifting, etc., can increase bone density. This is turn can lead to lower risks of bone fractures of the hip, spine, and other body areas. There are some risks to physical activity and exercise, however, so if you are over 40 years old and haven't been exercising much lately, you should consult your doctor about whether it's safe for you to start an exercise program. Sports medicine doctors can also help you determine safe ways to exercise to protect your joints and muscles and build good health and endurance.