(CNN) Mark Jonas, a member of the Wisconsin Football Coaches Association Hall of Fame, knows what it takes to make kids into champions on the football field. He just took over the team at the Southern Door High School in rural Wisconsin and changed practice this summer to try to keep his players healthy.
Last year, the players did full-on tackling and blocking in practice, and some got head injuries, he said.
This year, Jonas has them doing form tackling, no-contact drills that teach tackling technique. When they block, they push against a sled rather than each other.
The changes seem to be working: No kids have showed signs of head injuries in practice or in games.
"I hate to be cliche, but I always think, 'what would you do if that was your kid?' You want your kid to be as healthy as possible and as safe as possible and enjoy the experience," Jonas said. "You don't enjoy the experience when you have a bad concussion. Our practices are for learning, not for beating the crap out of each other."
Practices in which kids don't pummel each other are exactly what the authors of a new study say it may take to reduce the number of chronic brain problems in high school football players without getting rid of the sport altogether.
Football is the most popular sport with high school boys; more than 1.46 million play. Over the years, participation has declined slightly as more parents and children have grown concerned about head injuries and the long-term effects of smashing into each other or the ground.
All 50 states have adopted some sort of concussion rules for schools, and districts have put rules in place to limit head injuries and make football safer. But it's not just concussions that are a problem. There's a growing body of evidence showing that chronic sports-related exposure to head impacts, not just in football, can cause microstructural damage and alter or impair some brain activity.
The authors of the study, published Thursday in the journal Pediatrics, suggest that a change in the way high schoolers practice may have an even bigger effect than previous approaches meant to restrict head injuries.
The researchers, from Indiana University, studied games and practices for three high school teams in the Midwest in the 2021 season. They observed practice and studied videos of the teams. Additionally, the players wore mouthguards with sensors in them. They also surveyed the players and parents.
They found that there were 7,312 head impacts among the 74 players: about 66.5 hits per student. Linemen caught the brunt of the head hits. There were the fewest head hits when the kids practiced "air" training, meaning drills without contact.
With 5,144 minutes of "air" drills, there were about 310 head impacts overall. In comparison, in 6,901 minutes of "thud" drills, in which players train at high speeds and restrict contact to above the waist, there were 3,360 head impacts.
"The limitation of impact-prone practice drills may reduce overall head-impact exposure," the study says. "This data are significant because athletes who are diagnosed with a concussion have shown to be exposed to frequent head impacts before the concussive event. This makes a strong case that minimizing head-impact exposure, especially before games, can be done by incorporating less impact-prone drills."
Dr. Elizabeth Matzkin, Mass General Brigham Orthopaedic Surgeon and Sports Medicine specialist in Boston, works with several high school and Division 1 college football teams. She thinks the suggestion of limited-contact practice is a good one.
"Unfortunately, concussion is a problem, and anything that we can do to limit I think not just concussion -- but what part of this article gets to is just head impact, you know, kids falling down, hitting their heads on the ground. Everything adds up," said Matzkin, who did not work on the study. "How we can modify practices to limit head impacts in our high school football players, it's a really good place to start."
Dr. Jeffrey Kutcher, medical director of the Henry Ford Kutcher Clinic for Concussion and Sports Neurology, said this study adds important and specific evidence to back up previous understanding of the sport.
"While this isn't a new idea or new concept, it definitely provides data that allows us to have stronger conventions about how we design football practice," said Kutcher, who was not involved in the new research.
The study authors suggest that the data can be effective only if coaches adopt a policy that emphasizes less time spent on "thud" and "live" drills and more time in lower-exposure drills. Whether coaches would be willing to change practice is something they would like to study more.
Jon Millett, athletic director at Cony High School in Augusta, Maine, said his football coach holds practices for the team that are a mix of no-contact and contact.
"You have to practice what you're going to do. There's no way to get around that," he said.
In practices, they use Guardian Caps, spongy lightweight devices that go on top of helmets and are designed to reduce the force of impact to the head. He says he isn't aware of any concussions on the football team this year.
"Even if it saved one kid from a [brain] injury down the road, it's worth it," Millett said. "Obviously, the objective is to keep everybody healthy and functioning so that they can be part of the team."
Jonas' players in Wisconsin also use Guardian Caps, even without full contact in practice. He said he grew up with a very different kind of practice, but "when you hit and hit every day," he thinks it puts kids at unnecessary risk of injury.
Working on hand and shoulder placement, doing drills, is enough. He said his kids know what they're doing on Friday nights.
"This is one of the hardest-hitting groups I've ever had in 26 years of being a head coach," Jonas said.
And it's paid off. Jonas' team is 8-0 in his first year coaching at the school. They're ranked fifth in the state.
"We just can't afford to have our kids hurt," he said. "Keeping full contact out of practice has worked great for us. Ultimately, the muscle memory is in the tackling for what you bring to that form, and this group of kids brings a lot, so we're really lucky."