When you strengthen your muscles, you also strengthen your bones. If you're not exercising, regardless of your age, you are setting your bones up for osteoporosis. A study from Deakin University in Melbourne, Australia shows that lifetime sports and leisure activity participation is associated with greater bone size, quality and strength in older men. The older men who exercised regularly when they were younger have stronger, bigger and tougher bones that are harder to break. (Osteoporosis International, June, 2006).

Another study from University of British Columbia showed that lifting weights strengthened the bones of women in their late sixties. The women were asked to use several weight machines three times a week for one year. At the end of that year, the women gained a tremendous amount of muscle strength, and they also had denser bones.

Weight-bearing exercise in early life helps strengthen bones for later life, and exercising to strengthen muscles also strengthens the bones on which these same muscles attach. Another study showed that professional tennis players' bones in the arm that holds the racquet are much larger and stronger than the bones in the other arm. The arm bones are bigger, denser and stronger in athletes who whose activities involve upper body strength, such as rugby, rock climbing, kayaking, and weight lifting, while leg bone mineral density was highest in athletes whose activities included both running and strength training.