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Crowley: High school students should think twice before competing in endurance sports

Runners compete near the start of the girls

Runners compete near the start of the girls 5k run in the NSCHSAA League Cross Country Championships. (Oct. 28, 2012) Credit: Kathleen Malone-Van Dyke

Bone health usually isn’t a worry until back or knee problems emerge well into adulthood. And by that time it may be too late to do something about it.

We should start worrying about bone health when the body builds most of its adult bones: early childhood into teenage years. Researchers who study bone health suggest any bone mass gained after peak bone growth, which is around 20 years old for girls and a little later for boys, is minimal compared to any potential bone mass gain during adolescence.

Competing in sports is a good way to build strong bones during adolescence. But surprisingly, scientific research has found that endurance sports, like running, swimming and biking, can be more harmful on the bones of youths than compared to ball sports, like soccer or basketball.

Dr. Kirk L. Scofield, a sports medicine specialist at the University of Minnesota in Minneapolis, conducted a study last year, which can be found in Current Sports Medicine Report(, on the bone health in endurance athletes. He found that adolescents who compete in endurance sports have a lower bone mineral density (BMD) than those who compete in other sports. And in some cases, endurance athlete’s bone density is lower than children who do not compete in any sport at all.

Why does bone mineral density matter?

Low BMD increases the risk of stress and fragility fractures, both while an athlete is actively competing and later in life. While high BMD, if increased by as little as 10 percent during childhood, can delay osteoporosis by 13 years .

In a New York Times interview on August 5, Dr. Scofield explained how repetitive stress, which is the key to endurance sports, can tear down bone and is not the best for increasing bone strength.

Although lifelong studies have not been completed, there are instances when children grew more fragile after competing in endurance sports. One, albeit extreme, example is three children who ran marathons before they were each 10 years old. All of them sustained injuries, either in their knees or hips, before they were 20.

Injuries can occur in any sport, but bone mineral density of young endurance athletes has been proven to be consistently lower than that of sprinters, gymnasts or ball sports athletes, resulting in weak bones that can last well into adulthood.

Running and swimming, the most common endurance sports for youths, should not be avoided completely, though. They can still be beneficial to a child’s health if mixed with other sports.

Most students who take part in these punishing sports, with their intense workouts, do so to either stay in shape or get a scholarship. Those looking to stay in shape may see short-term benefits but long-term health problems. And those aiming for a scholarship do not need to give up all other sports. There are countless examples of runners and swimmers who participated in a variety of sports, yet still got scholarships.

Children should wait for college if they want to compete only in an endurance sport. Unless they prefer having bad knees, weak hips and the physical endurance of grandpa. 

Patrick Crowley is a Newsday Opinion intern and a high school student on Long Island.