I have written many times about the risks with single-sport specialization, where kids as young as seven or eight years old play only one sport and often play it year-round. I’ve always felt that focusing on one sport intensely at an early age increases a child’s risk for suffering a serious overuse injury. But is it the single sport specialization that is the problem? Or is it the higher volume of training that comes with playing that sport that is the underlying culprit?

A study recently published in the American Journal of Sports Medicine tries to answer that question. Neeru A. Jayanthi, MD and others collected data on athletes between the ages of 7 and 18 in Chicago. Before the season, the authors surveyed athletes and tried to assess their degree of single-sport specialization, which they defined as “year-round intensive training in a single sport at the exclusion of other sports.”

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Is single sport specialization bad for young athletes?

They assessed the degree of single-sport specialization by asking three questions:

• Can you pick a main sport?
• Did you quit other sports to focus on a main sport?
• Do you train more than eight months in a year?

Three “yes” answers categorized the athletes as highly specialized. Two equaled moderately specialized. One or zero counted as low specialization.

The authors then collected data on injuries among these athletes during the season and categorized them as acute injuries, overuse injuries and serious overuse injuries. A serious overuse injury was one for which a doctor recommended at least one month out of sports.

Injuries and single sport specializationYouth boys soccer players

The authors found some interesting data on injuries and single-sport specialization:

• The injured athletes were older than the uninjured athletes.
• Athletes who suffered “serious overuse” injuries had 1.90 times the odds of being a “highly specialized” athlete compared to athletes who did not suffer such an injury.
• The higher an athlete’s degree of sports specialization, the higher his or her risk of injury, overuse injury and serious overuse injury.
• Injured athletes reported more physical activity time in organized sports activity time than uninjured athletes.
• Young athletes who spent more than twice as much time in organized sports compared unstructured free play were more likely to suffer injuries, including serious overuse injuries.

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The authors concluded that single sport specialization by itself increased the risk of injury and serious overuse injuries in young athletes, independent of age and training volume.

Observations about single sport specialization

It’s hard to know what the underlying issues with single sport specialization are, but clearly it is more than simply the amount of training. The author speculated as to several possible explanations.

First, playing only one sport, especially at a high level, could entice young athletes to push themselves too hard and play through pain, risking injuries.

It’s also possible that playing only one sport trains and strengthens certain body parts and reinforces certain motions at the expense of others not used in that sport. These imbalances could lead to a higher risk of injury.Youth baseball pitcher in white

Novel recommendation

One of the most interesting points in the study came from looking at the number of hours kids spent playing their sports. Kids who spent more hours each week in organized sports than their age in years were more likely to be injured. While we need to study this variable more to confirm this finding, it could lead to a recommendation that is easy for anyone to understand. Basically a 12-year-old and his parents would need to keep the total number of hours he spent playing that sport each week at or under 12 hours.

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Encouraging Little League baseball coaches to use pitch counts
Give kids two or three days a week to rest

Reference: Jayanthi NA, LaBella CR, Fischer D, Pasulka J, Dugas LR. Sports-Specialized Intensive Training and the Risk of Injury in Young Athletes: A Clinical Case-Control Study. American Journal of Sports Medicine. Published online ahead of print February 2, 2015.