Young cyclists training to join the Tour de France could be causing irreversible damage to their bones.
The combination of cycling extreme distances and restricting caloric intake to reduce weight can decrease bone density to levels that put young athletes at greater risk for serious fractures and, in the long term, developing osteoporosis.
It is unclear whether these athletes can rebuild bone density if the condition is caught early enough. Most bone density is built in childhood and the teen years.
Researchers at Wake Forest University have found that approximately 50% of collegiate-level cross-country runners had abnormally low bone-density levels. Other endurance athletes such as cyclists and swimmers may be at even greater risk as they train just as hard and restrict calories to keep their weight down but without doing any of the weight bearing activity that runners do.
"Young cyclists could have the lowest bone density of all and be the highest-risk group," said Peter Brubaker, a professor in the Department of Health and Exercise Science and the executive director of the Healthy Exercise & Lifestyle Programs at Wake Forest. "Cycling doesn't build bones."
Brubaker and his team believe young endurance cyclists are at greater risk because training does not strengthen bones by putting weight on them, also called bone "loading." Loading exercises include jumping, running, dancing, stair climbing, aerobics, walking and skiing. Training burns so many calories that little if any are left to build bones.
"Young cyclists do no bone loading, but they severely restrict calories to compete," Brubaker said. "Biking is not generally the best activity for bone health."
More resistance training and weight training in the lower extremities could reverse bone loss. Wake Forest researchers plan to study such interventions in the future.
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