Don’t Follow This Fitness Advice

Dec 12 / Build Muscle

If I told you to go out and do whatever you could to jar your bones, the goal being to place as many stressful impacts on them as possible, you might think that I have a side business selling casts, crutches, and pain pills. But that’s just what a musclemorphosis.com in the New York Times told its readers to do. 

The piece is based on a study where scientists tracked how a group of adolescents’ bone density measurements changed depending on how many G-forces the kids put on their bodies. Here is what The Grey Lady had to say about the results:

(Adolescents) who experienced impacts of 4.2 G’s or greater — though these were infrequent — had notably sturdier hipbones. Additional work done by the same researchers showed that running a 10-minute mile or jumping up onto and down from a box at least 15 inches high was needed to produce forces that great. The significance of these findings is that people should probably run pretty fast or jump high to generate forces great enough to help build bone.

In other words: “Since kids benefit from putting a ton of force on their bones, you will too!”

The problem, says Mike Reinold, a Physical Therapist in Boston, is that kids and adults are inherently different. “Kids are always out playing, moving around, and their bones are constantly growing,” he says.

Yes, stress helps bones get stronger, but high impact activities can be detrimental to the average adult, especially if he or she has a desk job, says Reinold. “The more sedentary a person is, the more likely it is that their body has adapted to that lifestyle in a way that just isn’t conducive to doing a lot of impactful exercises.” 

Your body is an animal of efficiency. Slouch all day and your posture becomes slouchy. Lean to one side as you sit at your desk and your hips “remember” that comfortable position and become misaligned. Keep your arms below your neck all year, and your shoulders lose the mobility required to properly reach overhead, explains Reinold. Sure, ingraining those bad habits throws your body out of whack, but it’s what’s most efficient when you sit around all day; if you never go to point B, why not just get really comfortable in point A? 

The same rule holds true for bones, which are actually ever-changing tissues: if you never stress them—i.e. you do a lot of sitting and not much exercise—then your bones have no need to be strong and actually become weaker.

“Adding a lot of stress in the form of running, jumping, and bounding to a weak, misaligned structure can lead to injury,” says Reinold. “In sedentary people, high impact moves can bring on sore joints, arthritis, or even a painful stress fracture.” And that’s especially the case if the person is overweight, where each mile run or box jump carries with it that much more force.

Even professional athletes aren’t always ready for high impact moves, says Kevin Carr, C.S.C.S., a trainer at Mike Boyle Strength & Conditioning, in Woburn, MA, who trains everyone from NHL, NFL, and MLB guys, to accountants and stay-at-home moms. “Olympic lifts are the highest impact moves,” he says. “Those lifts can help an athlete perform better, but I’ll only have the athlete do them if he has really great movement patterns.” Otherwise, they could just put the person on the injured list, and those lifts are also simply “not worth it” for the average person. 

It’s a risk versus reward proposition, says Carr. “If you have bad movement patterns, the potential rewards from high impact stuff just aren’t worth the risks.” That’s especially true for the regular Joe, whose income doesn’t depend on his athletic performance. Carr’s go-to for helping his clients build bones of steel is actually basic, safe, weight exercises, which studies show bolster bone.

So the fix, of course, is not to avoid exercise or placing impact on your bones. “If you’re sedentary, simply ease into a workout routine that focuses on fat loss, strength, and mobility,” says Reinold. “Don’t go too hard too soon.” Mobility work can shore up your faulty movement patterns, while strength and fat loss work will help your bones and also make you feel and look better (in addition to providing many other health benefits). Once you’re comfortable with the basics, progress into more stressful moves.

And for relatively fit guys, there’s probably no need to stack your routine with high-impact exercises, says Reinold. “Just lifting weights and the occasional jog or jump rope session is enough to strengthen your bones.” But if you notice that an activity hurts, avoid it and see a physical therapist.

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