The rise in reported-concussion rates coincides with the passage of state legislation aimed at curbing brain injuries, as well as a surge of media attention to the problem. More athletes are coming forward to report moderate symptoms, which the American Orthopaedic Society for Sports Medicine suggests “may point to a lower threshold used by healthcare providers in diagnosing concussions in more recent years.”

But that doesn’t mean the head blows are inconsequential. A team of researchers from the Center for Injury Research and Policy that studied concussions among high-school athletes concluded in a 2014 report that the rise in diagnoses resulted from greater awareness among coaches, parents and athletes and not “an overdiagnosis of insignificant hits to the head.” Some of those hits may be the by-product of year-round, single-sport play that many young athletes engage in, generating more bodily hurts of all kinds. “If you’re seeing more overuse injuries, you’ll probably see more concussions,” Nowinski said. And research suggests that concussions are still underreported. An exhaustive 2013 study by the Institute of Medicine on concussions in youth sports summarized the cultural barriers to reporting like this: “Youth profess that the game and the team are more important than their individual health and that they may play through a concussion to avoid letting down their teammates, coaches, schools, and parents.”

Some head injuries, of course, are too ugly to miss. During a scrimmage last August, a running back on the Kearny, New Jersey, high-school football team was knocked out when a linebacker from the opposing team lunged at him and they banged helmets. It wasn’t a proper tackle, said John Kryzanowski, the head coach of the Kearny team, and it didn’t help when his player landed head first. “We immediately ran out on the field, and so did the trainer,” Kryzanowski said. Paramedics eventually arrived, and the player woke up, but the concussion kept him off the field for three weeks. In addition to the state-mandated concussion training he has received over the years, Kryzanowski has educated himself on how to limit the injury in football, a sport he has coached for 14 years. He limits the amount of contact players experience during practice, requires the kids to practice their plays by running into soft bags rather than each other, and deploys “hawk tackling” to keep players’ heads out of tackles, among other measures. Most youth-sports coaches, he suggested, are conscientious about keeping players safe. “I don’t want kids to put their futures in jeopardy,” he said, and “most coaches are afraid of lawsuits.”

State lawmakers and sports governing bodies have taken some steps to respond to the science on concussions. By 2007, all states and the District of Columbia had passed modest legislation on concussions in youth sports, setting guidelines for when to remove an athlete from play after a suspected concussion, and suggesting when it was safe for the athlete to return. But just 21 states require coaches to be trained to recognize concussion symptoms, and no federal laws are in place that mandate concussion safety in high-school sports.