Leo Anderson was in the middle of a baseball game when he threw a ball he had just caught, heard a crunch in his elbow and fell to the ground.
That sound was a growth plate in his elbow breaking, and it ended the now-15-year-old's season last spring.
Doctors said the break was caused by overuse, and the Highland Park, Ill., teenager had surgery to place a pin in his elbow to stabilize it.
Anderson, a catcher who had been trying out pitching, wore a cast for 12 weeks before his comeback this fall, playing for the Slammers club team in Lake County. The high school freshman also had physical therapy until November and said he hopes to play for his high school team in the spring season, in addition to his other team.
But his father, Bill Anderson, said he now closely monitors his son's play, and that the injury was a warning. Leo, like many youth athletes, plays baseball 10 months out of the year.
"Quite honestly, it just didn't occur to me that he was overusing his arm," he said.
Doctors say overuse injuries in youth sports have increased significantly in the past decade. They blame it on children focusing on one sport early on and playing it year-round, sometimes on multiple teams at once.
"Sports specialization has led to almost an epidemic in sports injuries," said Dr. Elizabeth Matzkin, surgical director of women's musculoskeletal health at Brigham and Women's Hospital in Boston and assistant professor of orthopedic surgery at Harvard Medical School. "Kids are fatigued, and they're not strengthening the way they should be."