For one, the risk of injury is high, due in part to many kids’ decision to focus intensely on one particular sport. In 2016, the American Academy of Pediatrics warned that “the increased emphasis on sports specialization has led to an increase in overuse injuries, overtraining, and burnout.” An analysis in the medical journal Pediatrics of soccer-related emergency-room visits among children aged 7 to 17 reveals a dramatic uptick in injuries: Researchers found that the annual rate of injuries for every 10,000 soccer players rose by 111.4 percent between 1990 and 2014; the annual rate of concussions and other “closed head injuries”—when the head is hit, but the skull isn’t penetrated—over the same period went up by 1,595.6 percent. Girls are injured more than boys. Knee injuries, including ACL tears, are nearly four times more likely to bedevil female soccer players than male. (The American Academy of Orthopaedic Surgeons reported that female soccer players have a higher rate of concussion than football players.)

“Almost all researchers in the field agree that later specialization”—ideally, after the early growth spurt associated with puberty—“is the healthier route (from the perspective of the child’s overall well-being),” Richard Bailey, a senior researcher at the International Council of Sport Science and Physical Education, wrote me in an email. “And that is why they predominantly recommend … [the] sampling of multiple sports, the development of a broad base of movement skills, and delayed specialization as the preferable approach.”

U.S. Soccer, the sport’s national governing body, has a different perspective. The organization’s chief medical officer, George Chiampas, told me that findings from an upcoming study that he co-authored, which compared injury rates among boys on teams in its Development Academy, a program set up by U.S. Soccer to cultivate top players, found no difference between those who just played soccer and those who played additional sports. Is it ever too early to specialize? “It depends on the environment,” he said.

Unlike U.S. Lacrosse, which has come out in favor of multi-sport play, U.S. Soccer has taken no definitive position on specialization. “We’re still analyzing the research,” said Ryan Mooney, U.S. Soccer’s chief soccer officer. As evidence of the organization’s commitment to protecting kids, Chiampas pointed to a safety and injury-prevention platform, Recognize to Recover, and to the fact that in 2015, U.S. Soccer instituted a rule disallowing children 10 and under to head the ball. Chiampas also said that the organization has stepped up its coaching education and is deeply committed to creating a “culture of safety” for all players.

Intense youth travel teams can also send unhealthy messages, to kids and adults alike, about a family’s priorities. Club soccer can require heroic measures on the part of adults—driving regularly to and from distant games, giving over sacred weekends to a child’s pursuit, and dividing up the family to deposit different kids at separate venues. One of the main jobs of parents, said Madeline Levine, a psychologist and the author of The Price of Privilege: How Parental Pressure and Material Advantage Are Creating a Generation of Disconnected and Unhappy Kids, is modeling for children what adulthood should look like. Youth sports teams that require parents to devote huge amounts of time and income signal to children that grown-ups are an afterthought, and that being a parent is an exercise in passivity and boredom. “We have become so child-centered that what kids have to look forward to [when they become parents] is diddling with a cellphone and sitting passively, not being an active participant,” she said.