Why do I shrink in height as I age?

Q. I am 68 years old. I used to be 5 feet, 9 inches tall. I just visited my doctor, and my height was just over 5 feet, 7 inches. What causes me to shrink, and what can I do to stop it?

A. Around age 40, most people lose some height, and the decline often accelerates in later decades. While multiple factors contribute to this "shrinkage," maintaining bone density to help prevent osteoporosis and improving posture are two ways to stand a little taller.

When a hip or wrist bone weakened by osteoporosis breaks, it's the kind of crack we envision when we picture a broken bone. But fractures of bones in the spine, called vertebrae, are different. Thin vertebrae don't crack, but rather get crushed, like a cardboard box after too much weight is placed on top.

Most compression fractures in the spine occur without any known trauma or injury. And often, it happens without any symptoms. Sometimes, though, a vertebra collapses suddenly, which can be painful.

All types of vertebral compression fractures result in loss of height. You can decrease the risk of losing more height the same way you prevent or treat osteoporosis.

For instance, eat a calcium-rich diet. (You need sufficient dietary calcium to maintain bone density.) Also, take a daily vitamin D supplement. (Vitamin D helps the body absorb calcium.) I recommend 1,000 IU of vitamin D3. If you haven't had a bone density test, ask your doctor about ordering one. It can show whether you need medication for thin bones.

Healthy bones also require daily exercise, such as walking and weight training. Putting pressure on your bones helps maintain bone strength.

Paying attention to your posture and taking steps to avoid stooping helps add height. If you spend a lot of time in front of a computer, you may notice your back bends toward the video monitor, and your shoulders roll forward. Weak back and abdominal muscles also contribute to poor posture.

Two simple exercises that can strengthen these weak muscles and help you stand straighter are the Superman and plank poses.

To do the Superman, lie facedown with your arms extended overhead. Lift your legs, shoulders, and arms off the floor simultaneously and hold for two to three seconds. Rest and repeat the lift about five times.

For the plank, lie facedown with your forearms on the floor, legs extended, and feet together. Push into your forearms as you raise your body, so it forms a straight line from your head and neck to your feet. Keep your gaze down and engage your abdominal muscles. Do not let your hips rise or sag. (If this is uncomfortable, try it with your arms in a push-up position, with your hands on the floor.) Hold for up to 30 seconds, and then lower your body. Rest and repeat two or three times.

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