Exercise is important so that your muscles do not go into atrophy. You must remember that your skeleton is alive and is constantly changing. To increase your bone mass, you must increase the flow of nutrients to your bones. Weight bearing and resistance exercises such as biking, baseball, aerobics, and dancing increases your muscle strength. The pressure and tension to the bone during these exercises increase your bone mass.
Osteoblasts are the agent in making bone.
Your racial and genetic heritage is another factor in getting Osteoporosis. Research has claimed that light skinned women from northern Europe, United Kingdom, and the far eastern countries have increased rates of Osteoporosis. Women from Hispanic, African, or Mediterranean countries have less occurrences of Osteoporosis. This stems from the fact that there is less synthesis of vitamin D in the skin of dark skinned individuals which results in a lower rate of bone turnover. Vitamin D is used in the body to bring calcium back out of the bones and causes the recycling of calcium in the body.