Former baseball players have big, strong bones in old age

Decades after exercising, male athletes see health benefits persist

PLAYING HARDBALL  For professional ballplayers, a childhood spent throwing baseballs can make the upper arm bone of the throwing arm twice as strong as that of the nonthrowing arm. Though strength fades with age, some of the strength benefits last until former players are in their 80s.

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Got baseball?  Spending one’s youth playing catch is good for the bones, with benefits that last a lifetime.

Years of hurling balls boosted bone size, mass and strength in the throwing arms of current and former professional ballplayers, researchers report March 24 in the Proceedings of the National Academy of Sciences. Though bone mass withered away when players retired, some of the extra size and strength stuck around — even 50 years after the athletes last played ball.

“If you exercise when you’re young, it makes your bones bigger and stronger for life,” says study coauthor Stuart Warden, a bone physiologist at Indiana University in Indianapolis.

Scientists have known for years that childhood physical activity makes bones stronger. But no one knew just how long the benefit lasted or whether it fended off fractures and bone disease such as osteoporosis, Warden says.

He and colleagues recruited 103 current and former professional baseball players to look at the differences between throwing and nonthrowing arms. Pro ballplayers have typically spent their youths heaving horsehides, Warden says. Because the game and its training methods haven’t changed much in 100 years, his team could compare today’s athletes with those who played decades ago.

The upper arm bone of a professional baseball player’s throwing arm is bigger (see cross section of bone, left), stronger and more massive than that of his nonthrowing arm. Some of the strength and size benefits last for decades — even if athletes stop throwing. Courtesy of S. Warden
Bone scans revealed major league differences in the upper arm bone strength of men’s throwing and nonthrowing arms.

“Just by exercising, they’ve made their bone twice as strong as the same bone on the other side of their body,” Warden says. “There’s no drug that you can take that will do that.”

Compared with nonthrowing arms’, throwing arms’ upper arm bones also had larger cross-sectional areas and more mass.

All of these bone benefits dwindled after players permanently stepped away from the plate, and mass gains eventually faded away completely. But retirees in their 80s kept more than half of the bone size benefits and a third of the strength benefits built up in their youth.

Still, people who don’t grow big bones in childhood haven’t struck out entirely on bone health: They might be able to cover their bases by exercising throughout adulthood. Former ballplayers who continued to throw staved off bone loss and retained more bone strength than those who didn’t.

The study convincingly shows that “you can expect some permanent benefits from physical activity,” says bone specialist René Rizzoli of Geneva University Hospitals in Switzerland. “This is an important public health issue.”

Kids who spend their time in front of the TV instead of at Little League games could miss out on a critical bone-building window that closes after puberty. “If we can get more children out and active, we can improve their bone health,” says kinesiologist Adam Baxter-Jones of the University of Saskatchewan in Saskatoon, Canada. Otherwise, he says, kids “will increase their risk of developing bone disease.”

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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