May 2014

Exercise Brings Bone Benefits that Last

Building bone as a young adult can have benefits that last a lifetime, a new study showed. The research also confirmed that physical activity as we get older can help us maintain bone strength.

Bone is a living tissue. It responds to physical activity by becoming heavier, bigger, and stronger. It does this best when we’re young. Bone mass usually peaks when we’re in our 20s. After that, we often begin to lose bone.

Studies of animals have shown that exercise during periods of rapid growth can lead to lifelong benefits in bone size and strength.

To see if the same holds true for humans, a team of NIH-funded scientists studied more than 100 professional baseball players at different stages of their careers. Baseball players were ideal subjects, because their throwing arms get a lot more action than their non-throwing arms. Baseball players also tend to retire from stressful throwing activities once they stop professional play. This allowed the scientists to look at the effects of physical activity long after intense throwing had ended.

The researchers found that the upper bones in the throwing arms of players were nearly twice as strong as the bones in non-throwing arms. Throwing arm bones had about 50% greater mass, size (total cross-sectional area), and thickness.

As players got older, the bone mass benefits from throwing were gradually lost. But about half the bone size benefits and one-third of the bone strength benefits were maintained lifelong. Players who continued throwing during aging lost less bone and kept even more of the strength benefits.

“Exercise during youth adds extra layers to the outer surface of a bone to essentially make the bone bigger,” says study leader Dr. Stuart J. Warden of Indiana University. “The bigger bone generated by physical activity when young has a means of sticking around long term to keep the skeleton stronger.”