It's never too late to strengthen bones with exercise. Every woman, and most men, will suffer from osteoporosis if they live long enough. Hip bones broken by osteoporosis do not heal, and must be replaced immediately. A study from Australia shows that regular exercise helps to keep bones strong and exercising into later life protects bones of older people even more ( Journal Osteoporosis International, August 2006). An earlier study from Sweden showed that men who were highly competitive soccer players in their youth and then gave up active sports did not have bigger and stronger bones and did not have fewer fractures than people who never exercised at all. On the other hand, people who did not exercise in their youth, but started and continued their exercise programs into later life did have larger and stronger bones.
A person has the strongest bones at ages 20 to 30. After that people lose bone continuously for the rest of their lives. Any activity helps keep bones strong, but exercises that put extra pressure on specific bones offer greater benefit. That is why weightlifting is a much better exercise for strengthening bones than swimming. The bones in the arm that hold the racquet in tennis players are much stronger than the other arm. Pick any sport that keeps you active and try to do it daily for the rest of your life. Take off only when you are tired or sick or your muscles are sore. More at: lifting weights makes bones stronger