However the authors of the study thought of a different explanation behind the numbers -- a lack of school nurses and P.E. teachers.
"We know that the number of school nurses had declined," said Nationwide Children's hospital's McKenzie. "Without school nurses on site, more students might be sent to the emergency room for treatment."
McKenzie also hypothesized that larger class sizes in P.E. might lead to less supervision and therefore more injuries. "Only 36 percent of the schools that require P.E. have a maximum allowable teacher to student ratio," she said.
Or, McKenzie suggested, the movement known as "new P.E." might be to blame. New P.E. incorporates more adult exercise activities such as jogging, fitness classes and weights than team sports and skills learning.
"But these are all speculations," McKenzie added.
One thing doctors didn't debate was the gender differences reported in the study. Boys were more likely to have head injuries, fractures or cuts, while girls were more likely to have strains, sprains and other non-contact injuries.
"With boys you see more aggressive activity that leads to more blunt trauma and forceful injuries, lacerations and head trauma," explained Dr. Amy Miller-Bohn of the University of Michigan. "With the female population, we see things more related to mechanical and anatomical issues, like strains and sprains."
In fact, Dr. Bohn has seen a major increase in sprains and other more severe injuries among her cheerleading patients. The rates of cheerleading injuries rose sixfold, going from 5,000 in 1980 to nearly 30,000 today.
As for McKenzie, she hopes her study will lead to more investigation to prevent injuries.
"I think one of the big messages from this paper is that a physically active lifestyle is important. The long-term effects of psychical activity outweigh the minor injuries," she said.