We always hear that exercise helps us lose weight — but it also helps us keep our bones strong.

“Exercise can reduce or prevent the age-related decline in bone density,” says Dr. Sonja Kukuljan from the school of exercise and nutrition studies at Deakin University in Australia. “It can also improve muscle mass, strength, balance and co-ordination.”

The best exercises to improve the quality and strength of your bones and reduce your risk of osteoporosis are resistance training and weight-bearing exercises, says Kukuljan. Osteoporosis is quite common after age 50, affecting 21.3 per cent of women and 5.5 per cent of men.

Resistance training can mean working with machines at a gym or using free weights. Kukuljan suggests getting your strength tested before you begin a program: This will help you decide what weight you should use. Medical guidelines suggest the best weights are those that allow you to do 10 to 15 repetitions for each exercise.

The ideal workout involves using eight to 10 major muscle groups, and this should be done at least twice a week, on non-consecutive days.

Then, after two or three months, higher weights can be used. “Strength training is likely to have multiple benefits, such as psychological, emotional, physical and social,” says Kukuljan.

On the days that you don’t lift weights, you can mix it up with aerobic exercise(walking, running, playing), flexibility exercises(stretching), or balance exercise(yoga).

Canadian researchers have discovered that to prevent future bone fractures, it’s important to boost not just the bone density, but also the quality of the bones. The Canadian Multicentre Osteoporosis Study included 9,423 participants in nine cities across Canada.

Osteoporosis and fractures can run in families, but there are some ways you can help lower your risk, including: not smoking, not drinking too much, and possibly avoiding anti-depressants called SSRIs (ask your doctor).

As you get older, being skinny (BMI under 20) is also a risk factor for osteoporosis.

“The thinner you are, the more likely you are to develop osteoporotic fractures,” says Dr. David Goltzman, a professor of medicine at McGill University, who gave a talk recently in Toronto about osteoporosis.

Taking enough calcium and vitamin D is really important too. Doctors generally recommend 1,200 mg/day calcium. Supplements are fine, but the best source of calcium is food. The optimal amount of vitamin D for many people is 800 I.U.