The Guardian and Yahoo.com—August 21, 2008
And for younger athletes, who tend to be disproportionately female, there are yet more health issues related to intense training before bodies are fully developed.
For younger competitors, the American Academy of Pediatrics' guidance on sport suggests that it is unhealthy for children under the age of 12 or 13 to specialise in any one activity.
Yet most young athletes, notably gymnasts, whose balance and flexibility is affected as their bodies develop, are training intensively by eight or 10.
"You see people of 16 or 17 years old with the bones of a 60 or 70-year-old," said Jordan Metzl, a physician at Hospital for Special Surgery in New York.
Most health experts agree that the problems stemming from obesity and sedentary lifestyles outweigh those of rigorous sport, and stress that with proper training and proper nutrition, risks can be avoided.
Some suggest that athletes are also more susceptible to eating disorders, whether in "aesthetic sports" like gymnastics or diving, or those like wrestling, where diuretics are common.
"You have to be thin, perfectionist, driven and willing to push yourself," Metzl said of young, female athletes.