ABSTRACT: Lindsey Vonn was skiing by her second birthday, Michael Phelps was in the pool at age seven and under the wings of Bob Bowman by 10, and Wayne Gretzky was skating with 10-year-olds—when he was six. While child prodigies are, by definition, the exception to the norm, they help set public perception. Want to raise the next Vonn? Make sure your daughter’s skiing before she can walk. Heck, don’t even let her walk. But as more and more kids get their starts earlier and earlier, we have to ask: Does specializing in a sport at a young age make your kids any better, and what does it do to their health?

HYPOTHESIS: Specialize from a young age if you want to succeed, but prepare to pay the price in injuries and burnout.

METHODS: An article in the journal Sports Health: A Multidisciplinary Approach reviewed the most pressing questions facing young athletes and their parents: Do children who specialize at a young age perform better than their peers down the road and do they suffer more injuries?

Researchers combed through articles from 1990 to 2011 looking for answers, and they also tapped into a recent study conducted by the article’s lead author, Dr. Neeri Jayanthi, the medical director of primary care sports medicine at Loyola University Chicago, that examined injury rates in 519 tennis players ages 10-18 who spent, on average, 11-15 hours a week training.

RESULTS: The kids who specialized in tennis were 1.5 times more likely to report an injury, regardless of their total—think: all activities included—training time. When it came to performance, several studies showed that in sports like cycling, swimming, and skating, those who started training intensely around age 15 were more likely to become elite-level athletes (defined by podium placings in European competitions and top-10 results in World and Olympic events) than their peers who started training earlier.

DISCUSSION: The game is changing, and it might not be for the best. Increasingly in recent years, youth sports have evolved from “child-driven, recreation free play for enjoyment to adult-driven, highly structured, deliberate practice devoted to sports-specific skill development,” reads Jayanthi’s review. While parents make the initial push by introducing their kids to a variety of activities, coaches encourage young children to specialize—to train year-round in a single sport to the exclusion of others.

The problem: Settling in on a single sport before age 15 won’t always to lead to long-term success, Jayanthi says. The contradictory example of Tiger Woods might be first to come to mind, but “if we look at all these athletes as a group, it’s an uncommon thing to get to the top level by only doing one sport early on,” he says. Overall, children who specialize at a young age have higher rates of burnout, peak sooner, and perform inconsistently compared to those who wait. Diversifying, then, with some exceptions, is the safer bet.

While sports like gymnastics require peak performance before maturation and hence specialization, endurance events are a whole different question, Jayanthi says. “You can make a late decision about being an endurance athlete and still be successful.” Just look at pro cyclist Evelyn Stevens (who began racing after a career on Wall Street) if you need any convincing.