This chair squat exercise is geared toward special populations such as seniors, people with osteoporosis, joint problems or general deconditioning, but it can be performed by anyone. (Jenny DeMarco )

People work out to tone muscles, lower blood pressure or look good in a swimsuit. But there is another — less talked-about — reason: to build bone.

In youth, bones seem so hard that it’s difficult to imagine them as living tissue that grows and changes, just like everything else in our bodies.

But they do. And they grow stronger and better with the right nutrition and exercise.

Exercise

“Any type of weight-bearing endurance exercise such as walking and running helps,” says Andrew Wolff, a D.C. orthopedic surgeon.

So, if running is not your forte, walk or hike and maybe add some resistance exercise such as weights and resistance bands, suggests Wolff, to keep your bones strong, and, in later years, maybe even prevent osteoporosis.

Anything that “places force across the bones” helps maintain healthy bones, Wolff says.

[7 bone-strengthening exercises]

“It doesn’t make a difference as long as you are doing something,” he says.

This is because bones — just like muscles — break down and rebuild throughout our lives. This process is particularly active in adolescence and early adulthood, when we rebuild faster than we break down (referred to as “peak bone mass”).

“The more active you are when you’re young, the better it is,” says Jenny DeMarco, a D.C. personal trainer. “You’re banking it for later when the bones start deteriorating.”

That sounds ominous, but the truth is that even as bones start breaking down faster than they rebuild, particularly after menopause (there is a hormonal component to the breakdown), you still can keep rebuilding and maintain bone density with the right type of exercise, DeMarco says.

“If you are postmenopausal but you don’t have osteoporosis, you can do just about any resistance training and weight-bearing exercise anyone else can do,” DeMarco says.

And even if you have osteoporosis — or its precursor, osteopenia — you still can do exercises other than bends, twists and heavy weights, she says, which can put the spine and hips at risk

DeMarco recommends that clients with osteoporosis — once they are cleared by a doctor — should work out at least 30 to 60 minutes two to three times a week, with an emphasis on core and balancing (for example on one leg) exercises.

“Posture is important for everyone, but even more so as we age,” DeMarco says, adding that her most frequent instruction is to “bring your shoulders down and back.”

In addition to strengthening the actual bones, the weight-bearing and resistance training also strengthens the muscles, which help give the skeleton stability (in fact, the muscles we are talking about are called the skeletal muscles).

Nutrition

Exercises, though, need to be supported by the right nutrition, says Isabel Maples, a local registered dietitian and spokeswoman for the Academy of Nutrition and Dietetics.

“Physical activity can only build stronger bones if the building supplies — calcium, vitamin D, etcetera — are available,” Maples says.

Other nutrients — maybe less obvious — are important, too: protein, minerals and vitamins such as vitamin K and C, potassium, magnesium and manganese to name a few.

Where are these found?

“Dairy foods are some of the best bone-building foods,” Maples says. Others include dark leafy vegetables, canned sardines or canned salmon with bones, almonds and tofu.

“But as a registered dietician, in my experience, people who don’t regularly drink milk have a hard time getting the recommended amount of calcium,” she says, adding that three-quarters of the calcium in the American food supply comes from dairy foods.

[Ask registered dietitian Ellie Krieger your nutrition-related questions ]

Unfortunately, she says, people stay away from dairy because of the calorie content, and this sometimes has the unintended consequence of weakening bones in, for example, young female athletes.

So why not take supplements to make sure we get enough calcium?

“It’s better to develop good eating habits rather than just rely on supplements,” Maples says, partly because supplements might add a “leader nutrient” such as calcium and not supply the other important nutrients for bone health such as magnesium or protein.

Or they might give you too much of a good thing; a supplement might have 100 percent of your daily calcium, but depending on what you eat, you could be going way over the recommended amount. Adds Wolf: “Too much calcium intake can cause calcification of people’s vascular system,” which in turn can lead to heart problems.

So sticking with nutrient-rich food is the better option for the vast majority of people. Let’s face it, it’s hard to OD on calcium and other nutrients by eating turnip greens.

The right amount of calcium per day is somewhere between 1,000 and 1,200 mg, Maples says. The higher number is for adolescents and postmenopausal women.

In order to get that amount in regular food it would take roughly three cups of skim milk or three cups of cooked collard greens.

Other lifestyle choices that improve bone health avoiding tobacco products and moderating alcohol intake, Wolff says.

He also suggests that you talk to your doctor before taking any supplements. That also goes for any exercise program that you start after menopause. If you are at risk for osteoporosis (Caucasian and Asian postmenopausal women in particular), a doctor might recommend a bone scan to check bone density before you start doing any high-risk exercise, such as overhead squats.

Because unlike many other musculoskeletal conditions, there is no particular pain associated with osteoporosis. The only indication — if any — might be a rounding of the back.

“It doesn’t hurt until you have a fracture,” Wolff says.

Boston is a fitness trainer and freelance writer. She can be found at www.gabriellaboston.com.

More from Wellness:

7 bone-strengthening exercises

Is technology spoiling your workout?