Are Gawky Adolescents More Injury Prone?

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Does the onset of puberty make a young athlete more clumsy? Many of us, particularly the parents of budding adolescents, would answer with a resounding yes. But it’s a question that has intrigued and vexed scientists and coaches for some time, and it has implications for how young athletes should be trained.

Children long have been thought to suffer through a physically gawky stage during the so-called tween years, beginning around age 11 or 12. It’s a time when most parents worry that their children are at particularly high risk of hurting themselves on the playing field, and there is some evidence, though limited, that sports injuries do spike around this time. A nationwide study from last year of running-related injuries in young people ages 6 to 18 found that 13-year-olds were the most likely to get hurt, and that typically, their injuries were caused by falls; the youngsters seemed to be tripping over their own growing feet. Similarly, epidemiological studies of knee injuries in female athletes have found that they occur far more commonly after a girl has entered puberty and undergone a growth spurt.

But other recent exercise science, somewhat surprisingly, has not been able to confirm the existence of an adolescent awkward stage. A few years ago, when scientists at the State University of New York at Buffalo tested 60 adolescent boys and girls on a series of tests of motor skills, they found that, consistently, the youngsters who’d begun puberty performed better than the children who had not. They ran faster, jumped farther and threw a ball a greater distance than the less physically mature children. The researchers concluded that there was no evidence of a physically awkward developmental period during puberty, only of consistent physical improvements.

Now, a review article in The British Journal of Sports Medicine sheds new light on why the teenage awkward phase may be so hard for scientists to detect. It may be a result of the subtlety of the growth period’s effects — and reflect the fact that it involves not just the changing adolescent body but the even more mutable adolescent brain.

For the review, researchers from the Cincinnati Children’s Hospital Medical Center and the Ohio State University gathered dozens of studies examining adolescent development. Most did not directly study exercise or sports. Instead, they looked at how children, adolescents and adults learn to control and position their bodies. The process is astonishingly complex, involving vision, touch, hearing, multiple sets of muscles and many different areas in the brain.

An interesting experiment cited by the review showed that when children ages 9 to 11 were outfitted with infrared sensors to capture their movements and then faced with a cone in their walking path, they edged around the obstacle quite differently than adults. The adults, nearing the cone, tended to reorient their bodies in one fluid, prolonged movement, changing their stride length and the direction of their feet well in advance of reaching the cone. The children, on the other hand, sighting the obstacle, would begin turning their heads and trunks before shifting the direction of their feet. As a result, their bodies displayed considerably more “yaw, pitch and roll,” in the felicitous phrasing of the researchers, than adults, and they were closer to the cone before they could manage to realign their feet and turn away from it.

“Children have to learn proprioception,” or how to orient their bodies in space, said Timothy Hewett, the senior author of the review.

Apparently as part of that process, “there seems to be a shift at some point during adolescence in which the brain processes information” about body positioning, said Catherine Quatman-Yates, a postdoctoral research fellow at Cincinnati Children’s Hospital and lead author of the review. Recent functional magnetic resonance imaging studies of people in motion, cited by the report, found that before puberty, children primarily show activity in subcortical regions of their brains when, for instance, they reach for an object, while adults primarily rely on the more sophisticated cortical regions of the brain to direct and integrate movements. This shift in brain function most likely occurs in adolescents just as they are shooting up in size. “The body is changing and so is the brain system” that controls body movement, Dr. Quatman-Yates said. “It’s hardly surprising that balance and postural control could be negatively affected.”

In other words, the bulk of the available science about adolescent development suggests that there is a period during which young people, even those who have always been superb little athletes, are going to trip over their own feet.

How can you tell, though, whether your child has hit that gawky phase, and can you do anything to help?

“Have your child do a drop-jump test,” Dr. Hewett suggested. Chalk one of the child’s fingers and have him leap as high as he or she can from the floor, marking the wall with the chalk. Then have him drop from a one-foot box and leap up immediately after touching the floor. “A well-coordinated kid will leap higher after dropping from the box,” Dr. Hewett said. An adolescent in the midst of his or her awkward stage probably will not. In that case, ask your child’s coach to incorporate balance training into warm-ups and training routines, Dr. Hewett said. But don’t panic. “Most kids,” he said, “adjust.”