Weight training has long been associated with numerous health benefits, including increased muscle mass, decreased bodyfat levels, healthier organs, improved moods and outlook on life, etc.
A lesser-known, but very significant benefit of weight training is its effects on bone density. This is beneficial for people as they begin to age into the middle of their lives, when bone density begins to decrease. It is also especially useful information for young women, whose bone density starts to decrease at a younger age than men.
This article will look at the various studies that show the link between weight training and increased bone density, the specific types of exercises that do the increasing, and surprisingly, which exercises may actually decrease bone density.
In 2009, researchers from the Bone & Joint Injury Prevention & Rehabilitation Center at the University of Michigan reviewed research as far back as 1961 to determine the impact exercise has on bone density and bone health. They discovered three of the main characteristics of exercise that have the largest impact on increased bone density:
1. Strain frequency of the exercise
This typically has a higher occurrence in running, where the impact to the bones occurs frequently during the workout.
2. Strain rate of the exercise
This is typically higher in exercises that include jumping or plyometrics, where the rate at which the impact is felt is high.
3. Strain magnitude of the exercise
This is highest on weightlifting or gymnastics, where the force/impact of the exercise is greatest.
Evidence has also shown that weightlifting two or three times a week seems to stimulate bone formation and calcium retention. The forces of muscle pulling against bone stimulates the bone building process.
Interestingly enough, swimming and bicycling are not on the list of exercises, and there is some evidence that elite level cyclists actually lose bone density during high intensity training. Researchers are not entire sure of the causes of this finding, but some of the theories include:
The non weight-bearing nature of cycling put little strain magnitude (see above) on the bones.
Minerals, including calcium, are lost at an enormous rate during hours of sweating.
The possible energy imbalance (more calories are used than consumed) during hours of intense exercise.
The fountain of youth has yet to be discovered, but I think strength training is about as close as we can get. Researchers at Tufts University found that normally women are only able to slow their bone loss, but thanks to strength training they can, along with people of any age, can actually increase its density, not just slow its loss. Because 9 out of 10 hip fractures result from falls, it seems like common sense to engage in strength training to help decrease the risk.
Men can also have brittle bones, but women–especially thin women–who are past menopause are at an even greater risk. If you’re thin, you have less weight bearing down on your bones, which translates to losing bone density even faster.
Strength training may be perceived as something that is best left to the silverbacks, but in reality it something that should be implemented by people from all walks of life, regardless of age. Not only will it make you stronger, more conditioned and an all around better person, it will also increase your longevity and keep your bone density high for the remainder of your days.
-R.S. Rector, R. Rogers, M. Ruebel and P.S. Hinton, Participation in road cycling versus running is associated with lower bone mineral density in men. Metabolism, 2007.