I devoted my pedestrian athletic career to one sport -basketball- and eventually blew out my knee.  My daughter did the same thing.  Not exactly a scientific study but our first hand/knee experience with a singular focus on one sport has some new scientific support.  United Press International (UPI) reports that  Brown University researchers found that kids who concentrate on only one sport may be at greater risk of stress fractures, tendinitis and knee injuries.

It's kind of like repetitive injuries at work. The study found that kids who do the most hours of intense activity per week, which also happens to be kids focusing on one sport, are most likely to be injured. Specialization did not significantly increase boys' risk of injury, but baseball, gymnastics and cheer leading did increase the risk. For girls, specialization in any sport increased their risk of injury by about 30 percent.

"The findings are a result of following more than 10,000 older children throughout the United States......coaches, parents and doctors (should) urge children to engage in less intense, less specialized training.

The report was published online recently in the Orthopaedic Journal of Sports Medicine.