How does strength training slow bone loss?

DEAR DOCTOR K:

I was recently diagnosed with osteopenia. My doctor advised strength training because it can help slow bone loss. How does it do that?

DEAR READER:

Osteopenia is a thinning of the bones. It is often a precursor to osteoporosis, a more severe thinning of the bones. Osteoporosis puts you at risk for disabling, and sometimes debilitating, fractures.

Bones are filled with cells. Some cells build up new bone; other cells tear down old bone. In most people, those two processes are in good balance. But in some people, particularly as they grow older, more bone gets torn down than built up.

To reverse that imbalance, and the osteopenia that comes from it, you need to stimulate the bone-building process. Bone, like muscle, follows the “use it or lose it” rule. One way to “use it” is to exercise. When you exercise, particularly in strength training, it stimulates the formation of new bone. The tug of the muscles on the bone, and the weight that the bone is being asked to support, signal the bone-building cells to work harder.

Strength-training exercises build muscle by harnessing resistance — that is, an opposing force that muscles must strain against. Resistance can be supplied by your body weight, free weights, elasticized bands or specialized machines. No matter what kind of resistance you use, putting more than the usual amount of load on your muscles makes the bones stronger.

Strength training should target bones of the hips, spine and wrists, as these are the bones that are most likely to fracture.

People with osteopenia, like you, or with osteoporosis have to exercise carefully. A person should not do exercises that could cause thin bones to fracture. For example, I tell my patients to protect their spine. This means avoiding activities and exercises that require you to bend your spine, especially to lift a weight. Bowling is a common example.

I also advise my patients to avoid free-weight exercises and machines that put added stress on the spine. These include some leg-press machines, leg raises performed lying down, and squats done with weight bars resting on the shoulders.

A person with thinning spine bones needs to do strength-training exercises that build strong core muscles, such as the standing side bridge. I’ve put a description and illustration of this exercise below.

I don’t know your age, but it’s possible that you’re thinking as you read this: “I’m too old to do strength training, to work out with machines and weights and such.” That’s wrong. Supervised weight training in older people builds muscle and bone.

Finally, don’t stop with strength training. Add a few balance exercises to your routine to reduce your risk of falls.

 Standing side bridge

Exercises the lower back, side, and abdomen

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Stand next to a wall, so the wall is on your right. Position yourself about two to three feet from the wall. Place your left foot directly in front of your right, and bend your right arm at your elbow. Lean your forearm against the wall so you are tilted toward it at about a 15-degree angle. Keep your body and spine in a straight line. (A) Hold that position for 30 seconds.

Now pivot on your toes, turning so you are facing the wall. Your feet should be side-by-side. Lean both forearms against the wall. Again, keep your spine straight; don’t bend the torso. (B) Hold for 30 seconds. Finally, pivot on your toes again so the wall is now on your left side. Your right foot should now be in front of your left, and you should lean against the wall on your left forearm. (C) Hold for 30 seconds. Rest, and repeat the whole sequence for another set. (While most exercises in this workout are performed eight to 12 times in a set, this exercise is only done once per set.)

Try to move from one position to the next as fluidly as possible, maintaining your spine in a straight line. Once you are comfortable with this exercise, increase the amount of time you hold each position by about 15-second increments, working your way up to two minutes at each step.