Hurt Girls

Girls and boys diverge in their physical abilities as they enter puberty and move through adolescence. Higher levels of testosterone allow boys to add muscle and, even without much effort on their part, get stronger. In turn, they become less flexible. Girls, as their estrogen levels increase, tend to add fat rather than muscle. They must train rigorously to get significantly stronger. The influence of estrogen makes girls’ ligaments lax, and they outperform boys in tests of overall body flexibility — a performance advantage in many sports, but also an injury risk when not accompanied by sufficient muscle to keep joints in stable, safe positions. Girls tend to run differently than boys — in a less-flexed, more-upright posture — which may put them at greater risk when changing directions and landing from jumps. Because of their wider hips, they are more likely to be knock-kneed — yet another suspected risk factor.

This divergence between the sexes occurs just at the moment when we increasingly ask more of young athletes, especially if they show talent: play longer, play harder, play faster, play for higher stakes. And we ask this of boys and girls equally — unmindful of physical differences. The pressure to concentrate on a “best” sport before even entering middle school — and to play it year-round — is bad for all kids. They wear down the same muscle groups day after day. They have no time to rejuvenate, let alone get stronger. By playing constantly, they multiply their risks and simply give themselves too many opportunities to get hurt.

David Cooper, Hannah’s father, observed: “I once heard that the injury rate in the N.F.L. is 100 percent. It looks to me, in girls’ soccer, it’s the same thing.”

A study last year by researchers at Ohio State University and Nationwide Children’s Hospital in Columbus, Ohio, reported that high-school girls who play basketball suffer concussions at three times the rate of boys, and that the rate for high-school girls who play soccer is about 1.5 times the rate for boys. According to the N.C.A.A. statistics, women who play soccer suffer concussions at nearly identical rates as male football players. (The research indicates that it takes less force to cause a concussion in girls and young women, perhaps because they have smaller heads and weaker necks.)

If girls and young women ruptured their A.C.L.’s at just twice the rate of boys and young men, it would be notable. Three times the rate would be astounding. But some researchers believe that in sports that both sexes play, and with similar rules — soccer, basketball, volleyball — female athletes rupture their A.C.L.’s at rates as high as five times that of males.

But even football players, according to N.C.A.A. statistics, do not rupture their A.C.L.’s during their fall seasons at the rates of women in soccer, basketball and gymnastics. The N.C.A.A.’s Injury Surveillance System tracks injuries suffered by athletes at its member schools, calculating the frequency of certain injuries by the number of occurrences per 1,000 “athletic exposures” — practices and games. The rate for women’s soccer is 0.25 per 1,000, or 1 in 4,000, compared with 0.10 for male soccer players. The rate for women’s basketball is 0.24, more than three times the rate of 0.07 for the men. The A.C.L. injury rate for girls may be higher — perhaps much higher — than it is for college-age women because of a spike that seems to occur as girls hit puberty.

So imagine a hypothetical high-school soccer team of 20 girls, a fairly typical roster size, and multiply it by the conservative estimate of 200 exposures a season. The result is 4,000 exposures. In a cohort of 20 soccer-playing girls, the statistics predict that 1 each year will experience an A.C.L. injury and go through reconstructive surgery, rehabilitation and the loss of a season — an eternity for a high schooler. Over the course of four years, 4 out of the 20 girls on that team will rupture an A.C.L.

“Look at the girl on the left back with the ponytail,” she said as we stood on the sideline of a game at the Home Depot Center, a vast complex of fields in Carson, Calif., where the men’s and women’s national soccer teams train. “She really concerns me.” At first I couldn’t pick out whom she meant; there were lots of ponytails out there. “No. 8,” she clarified, and I fixed my attention on a tall, stiff-legged girl whose upper and lower bodies seemed not to be in communication with each other. She ran bolt upright, with very little bend in her trunk. Her knees seemed not to flex. When she came to a stop or slowed to change directions, she landed flat-footed. “She’s got really poor form,” Silvers said. “She won’t hold up running like that.”

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Silvers directed my attention to one more player, a girl who seemed light on her feet, quick and springy. When she changed directions, she stayed in what generations of gym teachers have called “the athletic position” — knees bent, butt low to the ground. Even when walking casually during stoppages in play, she seemed more lithe than the other girls. “She moves more like a boy,” Silvers said. “Believe me, that’s a good thing.”

In the 2000 soccer season, researchers calculated 37,476 athletic exposures for the PEP-trained players and 68,580 for the control group. Two girls in the trained group suffered A.C.L. ruptures that season, a rate of 0.05 per 1,000 exposures. Thirty-two girls in the control group suffered the injury — a rate of 0.47. (That was almost twice the rate for women playing N.C.A.A. soccer.) The foundation compiled numbers in the same league the following season and came up with similar results — a 74 percent reduction in A.C.L. tears among girls doing the PEP exercises.

The club structure is the driving force behind the trend toward early specialization in one sport — and, by extension, a primary cause of injuries. To play multiple sports is, in the best sense, childlike. It’s fun. You move on from one good thing to the next. But to specialize conveys a seriousness of purpose. It seems to be leading somewhere — even if, in fact, the real destination is burnout or injury.