(HealthDay News) — Bone size and strength developed with physical activity in males during youth is maintained to some extent in old age, regardless of activity level, according to research published online March 24 in the Proceedings of the National Academy of Sciences.

Stuart J. Warden, M.D., of Indiana University in Indianapolis, and colleagues conducted a cross-sectional study comparing arm differences in professional baseball players (throwing-to-nonthrowing arm; 103 participants) with those in controls (dominant-to-nondominant arm; 94 participants) at different time points. The authors sought to assess whether the effects of physical activity during youth persist with aging.

The researchers found that the benefits of throwing activities during youth, including increased cortical bone mass, area, and thickness, were gradually lost with age because of greater medullary expansion and cortical trabecularization. However, once throwing activities ceased, half of bone size and one-third of bone strength persisted throughout life in professional male baseball players. Among players who continued throwing during aging, some cortical bone mass and more strength were maintained as the result of less medullary expansion and cortical trabecularization.

“These data suggest that physical activity during youth should be encouraged for lifelong bone health, with the focus being optimization of bone size rather than increasing mass,” the authors write.

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