You've gotten the message that a calcium-rich diet is important for building strong bones. But have you heard that gardening and yard work can also be good for bone strength?

Studies have shown that women 50 years and older who actively worked in their yards or perform other weight-bearing exercises - such as walking, aerobics, dancing and jogging - have stronger bones.

Stronger bones means fewer fractures. Women after menopause and men after age 70 are at risk for osteoporosis, a condition that weakens bones to the point where they break easily. This most often happens to bones in the hip, backbone (spine) and wrist.

Osteoporosis is a major public health threat for millions of Americans today.

Yard work, it turns out, has many elements that make it a perfect exercise for building strong bones. There's a lot of weight-bearing motion going on in the garden - digging holes, pulling weeds, pushing a mower.

And the great thing about gardening is that you don't need a gym pass to do it. Also, exposure to sunlight boosts vitamin D production, which aids the body in calcium absorption. Of course, you should always cover up and wear sunscreen.

Exercises that help your bones
A survey by the National Osteoporosis Foundation showed that few Americans understand what types of exercise benefit bones. Almost half the adults surveyed falsely believed that weight-bearing exercises require the use of weight-training equipment. While strength training with weights does help bones, you don't need weights. Everyday activities are weight-bearing and can be worked easily into your daily routine. Weight-bearing exercises are anything that make you move against gravity while staying upright.

In truth, all of us at every age need to make weight-bearing activities - like walking, dancing and playing tennis - part of our lifestyle to keep our bones healthy.

Experts say that you should do weight-bearing exercise for at least 30 minutes most days of the week, to maintain bone strength and mass.

Examples of weight-bearing exercise are:

• Walking
• Gardening/yard work
• Jogging
• Aerobics
• Climbing stairs
• Cross-country skiing
• Soccer
• Tennis
• Dancing
• Rollerblading
• Hiking

Swimming and bicycling are excellent cardiovascular exercises. They are not considered to be weight-bearing, though.

Here are some simple steps to add weight-bearing exercise to your daily routine. Remember to check with your doctor before you start or change any exercise program:

• Walk your dog (or borrow a neighbor's) for 30 minutes (or twice a day for 15 minutes).
• Start a walking club during lunch hour with friends from work.
• Take the steps or walk up the escalators at your office, in the mall or at the subway or whenever possible.
• Do 30 minutes of housework and/or gardening four times a week. Not only will your house and yard be beautiful, but your bones will be stronger.