Weight training for bone density
Womens’ bones begin demineralizing and becoming less dense steadily from young adulthood on. This process accelerates after menopause. Men lose bone density as well, only usually much slower. Other than diet and drugs, what can we do about it?
You may have heard that resistance training is good for improving bone density, or at least stopping bone loss. What you may not have heard is that it’s not quite that simple. Not all resistance training methods and exercises are created equally for the purpose of bone-building. More often than not (at least as I have found in my years as a fitness trainer), women who are new to resistance training and looking to strengthen their bones look to strength-training machines, as they are frequently simple to use and offer helpful instructions on the placard. If not machines, they will try simple, single-joint, muscle-isolating free-weight exercises. Usually they will use low resistance for fear of getting “bulky.” They’ll target primarily only the areas in which they wish to affect cosmetic change. While this can causes some changes in mineralization, they will be minimal. To understand why this approach doesn’t work so well, I’ll explain a little about how bone-remodeling and building work.
From a resistance-training standpoint, there are two primary methods for stimulated bone-building: stressing the muscles and stressing the bones. First I’ll discuss the muscle-stress method. When we use our muscles, tension is increased at the muscles’ attachments to the bones via their tendons. The tension on the bone stimulates a piezo-electric response, whereby a small electric current is created along the line of pull stimulating the osteoblasts (bone-building cells) to go to work at the attachment site. Unfortunately, this effect is limited to the tendon attachements, so any increased bone-density is isolated and minimal.
The other, and much more effective method of bone-building is the bone-stress method. This method calls for, believe it or not, the “bending” of the bones. Our bones are hollow and flexible which makes them light and resistant to fracture. When a substantial compressive force is applied to the long-axis of a bone, the bone bows slightly creating a compressive stress inside the bend and a tensile stress outside the bend. These compressive and tensile stresses create the same piezo-electric response previously mentioned, only along the entire length of the bone, increasing osteoblast activity throughout the entire bone and affecting a far greater increase to overall bone-density.
What does this mean for your workouts? Instead of those simple, light, isolated, single-joint exercises such as bicep curls and leg extensions, go the other way with it. Do complex movements with heavier loads, working many joints and muscles simultaneously, such as squats or military presses. Such exercises offer mineralization benefits to not only the attachments of all the involved muscles (which are many), but also to the entirety of all the bones loaded longitudinally (in the case squats, that’s the upper and lower legs and arms and the thoracic and lumbar vertebrae).
So, ladies, if you want to use weight-training as part of your bone-health regimen, you’ll have to redefine what you may think of as a “woman’s workout.” That means big movements, few or no machines, and heavier loads… a workout traditionally though of as more of a “man’s workout.” But hey, what’s good for the goose is good for the gander.