The National Football League (NFL) made headlines in 2024: first, for reporting that the number of player concussions had increased across the league for the second year running, and then for announcing the introduction of new helmets, including position specific helmets, for the 2024-25 season. A few weeks later, the league also okayed the use of Guardian caps, a padded soft-shell cover, during practices to help reduce impact during games. The only problem, said Nauman, is that there is little data to say these changes help.

“The extra padding doesn’t hurt unless it presents a false sense of security,” he said. “When we tested the Guardian caps when they first came out using the National Operating Committee on Standards for Athletic Equipment (NOCSAE) standard, they essentially collapsed so quickly they didn’t absorb a meaningful amount of energy.”

The NOCSAE standard involves two key tests. The first places a helmet, minus the face guard or any other additions, on a standard head form and drops it onto a steel anvil. The second has the helmet struck by a pneumatic ram traveling at 19.6 meters per second. These tests, however, only measure the force hitting the outside of the helmet. They do not look at the forces on the inside, which are more important when you are trying to prevent concussions.

“The ways helmets are tested are not at all like how a kid gets hit in a game,” he explained. “So, they can’t tell us much about what the helmet is doing in terms of protection beyond skull fractures.”

Nauman and colleagues were able to get much more meaningful data when they took a page from military traumatic brain injury (TBI) researchers and started to use an impulse hammer to record the applied force for the head form alone and then to different locations on the helmet, to measure the reduction of impact the helmet afforded.

“We learned that angular acceleration, the force we think does the most damage, is a disaster when it’s at the back of the helmet,” he said. “Think of the quarterbacks or the receivers who hit the back of their heads on the turf when they are tackled. Our data says some helmets only absorb about 10 percent of that impact. A few do go up to 50 percent, but every other location on the helmet is closer to 65 to 80 percent absorption.”

Ellen Arruda, a mechanical engineer who works on football helmets at the University of Michigan, said her research demonstrates that helmets, as currently designed, simply don’t dissipate enough energy after a hit. She’s been trying to improve their viscoelasticity, by optimizing the materials placed inside the helmet.

“You don’t have to change the outer shell of the helmet, which is generally polycarbonate or something similar to that,” she said. “You can put the right polymer, commercially available materials, on the inside that has the right dampening characteristics at the right frequencies, and they will do a better job of protecting the brain.”

While some have called for new-age materials to be used to make lighter, more durable helmets, Nauman said they aren’t needed.

“I’m very comfortable in saying that I think we can get to above 80 percent impact mitigation on every location on the helmet with materials that already exist,” he said. “We just need to test them in the appropriate way, collect the right data, and build from there.”

“If you have a sport where you are going to allow the ball to travel at high speeds and people are expected to catch that ball, there’s going to be risk,” said Lloyd, whose research focuses on baseball equipment. “We all must admit at the outset that many of these games are inherently risky. The question then becomes, how much risk are we comfortable with at what level?”

Susan Sokolowski, director of the Sports Product Design Program at the University of Oregon, said a good place to start is by defining and then working within what she calls an “athlete benefits model.”

“You have to look at all the different ways a piece of equipment can support the athlete in their sport,” she said. “You have to dabble in many areas, from thermal regulation, impact protection, compression, and aerodynamics, just to name a few. And that means you are going to hit trade-offs as you work on your design.”

Every engineer is familiar with trade-offs. It’s part of the design game. But Sokolowski said that working closely with athletes can help engineers interested in improving safety make sure they aren’t doing so at the expense of something else that matters greatly to the athlete.

“You want to create products with the athlete as part of the journey,” she said. “And it means taking the time to really understand the whole universe around the product, grasping what’s really needed, and then prioritizing and ranking those attributes to come up with something that people want to use.”

But the bigger challenge to making sports equipment safer, regardless of the sport, may be overcoming sports culture. Big companies shy away from making injury prevention claims because the causes of concussions and ACL tears are multi-factorial. And, let’s face it, no one is going to spend $200 on a pair of shoes solely for their injury-prevention qualities. (Well, except maybe an athlete’s mother.) Athletes generally want something that will allow them to play, and maybe even look like their favorite sports star. Still, Arruda believes that there are vast improvements that can be made with better data and more thoughtful approaches to design.

“We need more component testing so we can understand the components of each design. We need to understand the material and structural properties,” she said. “But, at the end of the day, making these changes is fundamentally a physics problem. When you learn the basic mechanics of the problem you are trying to solve—and there are so many fantastic experimental and computational tools to help with your accuracy, speed, precision, and possibilities for improvement—you can find a way forward. You can absolutely go for it.”   

Kayt Sukel is a technology writer and author in Houston.