What type of exercise is best for maintaining strong bones?

The key word here is “maintain,” since 95 percent of your mature skeleton is already in place by the age of 17 for girls and 19 for boys. Once you
reach adulthood, it’s basically one long fight against the slow but inexorable weakening of your bones. According to conventional wisdom, the key
to that fight is engaging in weight-bearing activities—those in which you’re standing and supporting your own weight rather than being seated. But
the latest research shows strength training can also play a key role—and in fact, lifting weights may be even more effective than some weightbearing
activities like elliptical training.
“Over the past decade, people have realized that bone is more dynamic than we thought. It’s actually a pretty responsive tissue,” says Heather
McKay, a professor in the faculty of medicine at the University of British Columbia and the director of the Centre for Hip Health and Mobility. It turns
out that training your bones has more in common with training your muscles than previously thought: if you stress them, they’ll get stronger. How
much stronger depends on what your body is currently used to, how big a load you apply, and how you apply it. Recent studies by McKay’s team
have found that short bursts of intense activity separated by brief rest periods—anything from jumping on the spot to squats in the weight room—
build bone more effectively than continuous, less intense activities.
This means that weight bearing, on its own, is a bit overrated. It’s true that the skeleton gets a bit of a workout from gravity whenever you’re
standing up, but you can stress your bones in a more targeted manner by training with weights. “Any time you’re increasing your muscle mass, the
tension of the muscles on the bone creates a ‘bending moment’ that stimulates your bones,” McKay explains. Lifting weights also allows you to
target vulnerable areas like your wrists, which get no benefit from your hours on the elliptical.
Another study by McKay’s group found that schoolchildren who jumped up and down between 5 and 15 times, three times a day (at the
morning, noon, and end-of-school bells) significantly increased their bone density. Since a quarter of your adult skeleton is laid down during early
puberty, it’s important to make sure children are doing the kinds of activities that build strong bones—and this study confirms that even small
amounts of intense, jarring activities like jumping are more effective than simply standing or walking around.
Numerous studies over the years have found that strength-trained athletes have greater bone mineral density than endurance-trained athletes,
lending support to the idea that building muscle is better for bones than weight-bearing activities like running. But a 2009 article in the Journal of
Strength and Conditioning Research showed that the differences aren’t that simple. Pamela Hinton and her colleagues at the University of
Missouri compared runners, cyclists, and strength-trained men. They did find that the strength group had the greatest bone density, but that was
only because they had the biggest bodies. The runners were leaner, but their bones were just as strong relative to their body size.
There was, however, a significant difference between the bone density of runners and cyclists, which suggests that it’s the repeated, jarring
impacts of running that produce stronger bones compared to cycling. As a result, Hinton recommends that those who engage in activities such as
cycling, swimming, and rowing consider adding a dose of either strength training or a higher-impact activity like running to their regimen. That also
means that elliptical trainers, which many people turn to precisely for their softer landing, suffer from the same shortcoming. “There’s no impact
force, as the steps of the machine move with you,” Hinton says