Nobody doubts the benefits of phys ed for children, especially as national child-obesity rates climb. But kids who are active are also at risk of getting hurt, and there are a lot more injuries than there used to be. From 1997 to 2007, annual gym-class-injury rates leaped 150%, from 4.39 trips to the emergency room per 10,000 kids to 10.9 trips, according to a study by the Center for Injury Research and Policy at Nationwide Children's Hospital. Six activities — running, volleyball, football, basketball, soccer and gymnastics — were responsible for 70% of the injuries. Boys, who accounted for 54% of those injured, were more likely to get hurt in team sports. Girls were likelier to get hurt while running or playing tennis. Why the numbers rose even as budget cuts reduced phys-ed programs is unclear. It may simply be that with fewer schools hiring nurses, more accidents are being treated in emergency rooms and thus being reported. It's also possible that heavier kids are less fit, making them more apt to get hurt.