But calcium alone can't build bone. Without vitamin D, calcium isn't sufficiently absorbed. Most people get enough vitamin D because skin produces it in sunlight. A lifelong habit of weightbearing exercise, such as walking or hiking, also helps build and maintain strong bone. The greatest benefit for older people is that physical fitness reduces the risk of fracture, because better balance, muscle strength, and agility make falls less likely.
Exercise also provides many other life-enhancing psychological and cardiovascular benefits.
Increased activity can aid nutrition, too, because it boosts appetite, which is often reduced in older people. The biggest reason older people don't get enough calcium, Recker says, is that they simply don't eat much. He suggests 30 minutes of brisk walking five days a week. Add a little weightlifting, and that's even better. It's always smart to ask your doctor before starting a new exercise program, especially if you already have osteoporosis or other health problems.