Whether young athletes are throwing, rowing, swimming or running, sports medicine experts have been warning for years against specializing in one sport and one position.
Orthopedic surgeons have been repairing blown-out shoulders, elbows, knees and ankles on a troubling number of athletes barely in their teens, and some youths have had to give up competing before they finish high school.
But now, a new report in the Journal of Athletic Training suggests injury from overdoing it in one sport continues into college athletics, particularly among women.
The study, which analyzed injuries among athletes on 16 teams reported by athletic trainers at the University of Iowa over three years, found that more than a quarter of all injuries involved overuse, and women's sports actually had a higher rate of overuse problems than those caused by acute injuries.
The Iowa study, led by Erin Heiden, a behavioral health and injury prevention researcher, found repetitive stress had the most injury impact on participants in women's rowing and among men's cross country and track and field athletes.
The highest overuse injury rates per 10,000 "athletic exposures" -- a game or coach-supervised practice -- were in four women's sports: field hockey, soccer, softball and volleyball.
The dangers of year-round training and play for younger athletes have been a concern for more than a decade.
For instance, one 2011 report in the American Journal of Sports Medicine followed nearly 500 young baseball pitchers between the ages of 9 and 14 for a decade and found that those who pitched 100 innings or more a year were at least 3 1⁄2 times more likely to sustain an injury that required surgery or forced them to give up the sport.
Other studies of fastpitch softball's underhand windmill pitching style -- once thought to be less stressful that overhand baseball pitching -- have recently suggested that the motion puts strain on the front of the shoulder and that pitch counts and innings need to be more closely monitored.
Whether you blame it on adults driving kids too hard, the rise of elite teams that play year-round or the pursuit of elusive college athletic scholarships only a handful will ever see, specialization has become commonplace among tens of thousands of youngsters in almost every sports venue.
"It used to be that teenagers were active in several sports throughout the year," said Dr. Greg Nicholson, a sports medicine specialist at Midwest Orthopaedics at Rush University Medical Center in Chicago. "Competition to make the team in high school has more young athletes focusing on one sport, forcing them to use repetitive motions and often resulting in injuries."
But there's also been grudging acceptance from the pediatric and orthopedic communities that the bodies of older teens, say, after 14 or 15, could handle a single-sport commitment, with proper conditioning and maybe some rest periods, and not suffer much from overuse injuries.
Fourteen-year-olds generally have stopped growing much around plates at the joints that are susceptible to repetitive injury at younger ages, the thinking goes.
At Iowa, Heiden and her colleagues said it's not clear why female collegiate athletes remain at higher risk from overuse. Structural differences in joints between the genders may be to blame, but it will take more study to find out, they said.
The researchers also noted that half of the overuse injuries required no time lost from the sport. That doesn't necessarily mean they weren't serious, just that they're approached differently than sudden traumatic injuries.
Rather than shutting down entirely to heal, athletes with overuse injuries are more likely to alter training routines and return to play even if they're still experiencing pain than they would with an acute injury.
For more information on overuse injuries and prevention, see www.stopsportsinjuries.org.