Exercise during youth builds strong bones for life

From ABC News in Science, 25 March 2014:

A study of major league baseball players’ pitching arms has shown that bone strength in later life is decided by the quality of exercises we do in our youth.

The research by US and Australian scientists is published today in Proceedings of the National Academy of Sciences throws a curveball at the concept of ‘use it, or lose it’ in the context of bone health.

Researchers examined the cross-sectional size of the humerus — the upper arm bone — it’s torsional strength, bone mass and bone mineral density of the throwing arms of 103 professional baseball players at various stages of their careers.

They found that even decades after players had stopped playing baseball, the cross-sectional size of the bone — which is a key determinant of bone strength — was largely preserved.

“The current paradigm seems to be that if you increase bone mass then you preserve bone strength over a lifetime, but we know that as we age the bone mass decreases,” says research Professor Marcus Pandy, chair of biomedical and mechanical engineering at the University of Melbourne.

“What we found was is that in these baseball players, whether they continued to pitch or not, bone mass did decrease, but the size of their bones did not decrease.”

Baseball players were used in the research because when they throw a fast ball, the muscles in the upper part of the arm twist and therefore twist the bone.

The CT imaging used in the study showed that over time, that twisting motion causes the outer surface of the bone to increase in size. Read more.