Weight-bearing exercise is the type of exercise you're supposed to do to boost bone density, a standard goal for those of us experiencing a loss of bone density/strength due to age, menopause, or drugs.
But it can be confusing trying to sort out which exercises are weight-bearing; which are weight-bearing, but might not be good for you; and which AREN'T weight-bearing, but still might help with your bone density. Confused? I used to be. But not any more.
In my previous post I talked about the various weight-bearing exercises that are good for you. Essentially, these are exercises where your bones support your body as you work against gravity, or work against some other resistance (e.g., weightlifting). High-impact weight-bearing exercises, things like basketball, soccer, and jogging, are generally avoided by those with osteoporosis, due to risk of fracture. Low-impact weight-bearing exercises (elliptical machine, Nordic machine, brisk walking, stair-step machine) are preferable.
Notice that impact refers here not to the effect these exercises have on you; but rather on the degree of physical stress they put your bones through. Basketball is high impact; your feet pound on the floor as you run down the court, and your bones absorb impact when you come down with a rebound. The elliptical machine is low-impact; your legs aren't subjected to any impact stress at all, since your feet never leave the pedals. See the difference? Keep it in mind when you're reading about high- vs. low-impact weight-bearing exercises.
So, I understand all that. Where I become confused is in trying to classify bicycling (which I love); swimming (which I loathe, but would do if it were good for me); and Pilates and yoga, both of which I pursue sporadically. Why aren't cycling and swimming good for bone density? And how about Pilates and yoga? Yes, or no?
Let's look at swimming first. Apparently swimming is inefficient at building bone density due to the fact that the water supports you, rather than your bones. Gravity pulls you down; the water buoys you up. Your bones aren't working hard.
Now, I don't really see much difference between a good, hard breaststroke, and doing "flys" on a Nautilus machine. Same motion, exactly. Water provides the resistance in one, a metal weight the resistance in the other. But I'll take the experts' word on it: swimming isn't your first pick for building (or even maintaining) bone density.
Then there's cycling. Here's an explanation I found that makes sense: cycling is NOT a weight-bearing exercise when you're sitting down. But it IS when you're standing up in the pedals, and your leg bones are bearing your weight. So cycling is a good low-impact (unless you crash) weight-bearing activity if you ride standing in the pedals.
And how about Pilates and yoga? Well, it depends. Each of those include times when you're lying on the floor simply stretching; and times when you're on your feet balancing, stretching, bending, or twisting (or all of the above). Now granted, some of those floor stretches are pretty strenuous; it's not easy rolling back to touch your toes on the floor behind your head! But your bones aren't supporting your body; the floor is.
As soon as you get up on your feet (or arms and legs), though, everything you do in Pilates or yoga is weight-bearing. Think dog pose in yoga; your arms and legs are bearing all of your weight. Think crawling your back up the wall in Pilates; your legs support you as you lift your back. And everything you do in each of these pursuits is low-impact (no pounding), perfect for those trying to avoid fractures.
So, what's the takeaway here? Use this information to build yourself an exercise program, one that suits your personality, pocketbook, and propensity for pushing yourself. After all, exercise the RIGHT kind of exercise comes with many fewer potential side effects than Boniva or hormone replacement therapy. It can also be free; no forking over money to the drugstore. What's not to like other than the fact that it's work?!
Next time, I'll tell you more about your bones than you ever thought you'd want to know: how they grow, what happens to them as we age, and exactly why exercise the right kind of exercise helps keep them healthy.