(Relaxnews) - The many health benefits of physical activity are well-known, with a new study citing yet another perk. U.S. and Australian researchers recently found people who remained physically active throughout their lives had stronger bones when they reached their golden years.

The study was commissioned by the National Institutes of Health and focused on bones in the arms of Major League Baseball players.

It was discovered that exercise contributes to bone size as well as strength. The research team worked with 103 professional baseball players and found "throwing arm" bones featured two times the bone strength of "non-throwing" arms. Bone size as well as density were measured.

The study showed bone size did not diminish after players retired, even if they didn't keep up a fitness regimen. Bone mass did eventually shrink in such players, however. Players who exercised following the end of their careers unsurprisingly reaped more bone strength benefits.

"This is an impressive level of maintenance, particularly considering that the baseball players had not thrown, or in other words, exercised, in over 50 years and were aged in their mid-80s," said study author Stuart Warden, associate professor and associate dean for research in the Indiana University School of Health and Rehabilitation Sciences at Indiana University-Purdue University Indianapolis.

While it's never too late to start an exercise routine, this study indicates working out and playing sports while young provides benefits that last well into old age.

"Exercise during youth adds extra layers to the outer surface of a bone to essentially make the bone bigger," Warden added. "This gives you more ‘bang for the buck,' as the addition of a small amount of new material to the outside of a bone results in a disproportionate increase in bone strength relative to the gain in mass."

The study was published in the journal Proceedings of the National Academy of Sciences.