COLLEGE PARK, Md. — A growing number of young athletes are focusing on playing a single sport, putting themselves at greater risk of serious injuries, physicians say.
"When athletes play one sport and one sport alone, there's probably more hours of competition in that one sport than there were competing if they had two or three other sports," said Dr. James Dreese, Maryland Terrapins team physician and an assistant orthopedics professor. "It's the hours of competition that puts them most at risk for having those problems."
Some parents think specialization can help their children become stars, earning college scholarships or even pro careers.
During the past decade, Dr. Chris Stankovich, a sports performance scientist, said he has noticed more and more children beginning to specialize in one sport.
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"Culturally speaking, more and more kids are seeing that a friend of theirs or a schoolmate is doing one sport year-round, so it kind of normalizes it," Stankovich said.
More than 44 million children in the United States participate in youth sports, according to a 2008 survey by the National Council of Youth Sports. But only about 6 percent of high school athletes go on to play football, baseball or soccer in college, according to the NCAA. About 3 percent play college basketball.
Specialization at a young age, however, can set young athletes up for serious injuries.
For example, the throwing arm of a baseball player who specializes in pitching too early can undergo major structural changes.
"There are some pretty significant adaptive changes that take place in the throwing shoulder with regards to the way it rotates and the way in which it's orientated that is most related to the hours of which the athlete is throwing," Dreese said. "The younger they are, the more that adaptive change tends to be."
Reggie Zayas, who serves as commissioner of the Marlboro Boys & Girls Club and a travel league in Upper Marlboro, Md., said about 40 percent of his kids specialize in baseball, usually by ages 9 or 10.
Kids on travel-select leagues are "falling behind the curve if they play multiple sports," Zayas said. "If you try to play (football, basketball and baseball) ... you're falling behind the curve because there are so many kids just concentrating on one sport."
Harry Hudson, president of Henlopen Pop Warner and coach of the Cape Vikings pee-wee team in Lewes, Del., tells his baseball players the same thing.
Hudson and his fellow coaches encourage kids younger than 12 to stay active and participate in as many sports as possible. But when they become teenagers, he advises them to consider specializing.
"When you move on to that middle school or that high school level, you need to start looking at your future," he said.
Some parents, like Hudson, view sport sampling as more dangerous than focusing on one sport.
"In football, you're using your shoulders by hitting people. You're using your legs also. You go into wrestling, and you're not giving your body enough time to heal. Now you're going right back into another sport that has to do with possible shoulder injuries," Hudson said.
But doctors argue that playing only one sport is more dangerous.
The movement toward specialization might produce more successful athletes, but it also results in more injuries. More than 3.5 million children 14 and younger were treated for sports injuries in 2010, according to the American Academy of Orthopaedic Surgeons. In contrast, 1.9 million were treated in 2002, according to the Centers for Disease Control.
Researchers at Loyola University Chicago's Stritch School of Medicine found in 2011 that single-sport athletes were almost twice as likely to suffer an injury as multisport athletes.
"Certainly, if you're throwing a baseball 10, 11, 12 months a year, you're going to have a much higher risk of injury than if you're throwing four, five months a year and maybe throwing a football a few months a year," Dreese said.
Chronic overuse injuries account for about half of new injuries in pediatric sports medicine practices, according to the International Youth Conditioning Association.
Children who specialize can develop Osgood- Schlatter syndrome — which causes knee pain — and os calcis apophysitis — which causes heel pain.
In adolescents and young adults, there's a risk of shin splints, and patellofemoral syndrome, also known as "runner's knee."
By playing a multitude of sports, kids are more likely to develop better coordination and muscle balance, doctors said.
"Children participating in a variety of different sports develop a lot of different skill sets in terms of coordination and muscle development," Dreese said. "Playing a variety of sports that require a variety of skills helps to develop that better than playing one single sport that focuses on just a few of those factors."
Stankovich warned that kids who specialize face psychological risks. They begin to look at their sport more like a job and run the risk of burnout.
"It doesn't take a doctor or an expert to tell you that when sports become so intense that they're day in, day out, it's not going to be as much fun for most kids," Stankovich said. "There's an apex that a person hits when they're performing a skill. You hit a point where it's no longer productive to put that kind of time and energy in it."
Most parents aren't looking for signs of burnout, Stankovich said, which includes loss of intrinsic motivation to play the sport, difficulty sleeping, irritability and lethargy. Instead, parents become intoxicated with their child's success.
"When you see kids who are not enjoying it anymore but mom and dad are still foot on the accelerator ... then maybe (the child) bottles that all up," Stankovich said. "At some point ... with all that cumulative stress, that's where they ... explode."
Burnout itself can lead to injuries. If children are tuned out mentally, they can lose their focus on the field or court. Burnout can be prevented, ironically, by participating in a variety of different activities.
Zayas, a father of two, played baseball and football throughout high school. His son, 11, did the same until he decided to concentrate on football last year.
"If the specialization occurs after several years of playing youth sports, I don't see anything wrong with it," Zayas said. "If they only concentrate on one sport since they've been 5 or 6, and they've been playing that sport until the end of their youth days, I think the kid is losing out on some different environments they could be in, and there may be potential somewhere else."