Football’s concussion problem has spawned a vast market of questionable solutions—unproven supplements, mouth guards claiming to protect against brain trauma, a collar marketed as “bubble wrap” for a player’s brain. If only preventing brain trauma were that easy.

Whether in an effort to save the sport and players’ brains or in a cynical ploy to profit off the fear of parents and players, the market for concussion technologies is booming. An eagerness to “do something” has led people to adopt or promote some pretty dubious products, says Kathleen Bachynski, an assistant professor of public health at Muhlenberg College. In a paper published in July, she and her colleague James Smoliga documented the increasing availability of pseudoscientific concussion products.

The Federal Trade Commission has also been monitoring bogus claims. In 2012 it prohibited a company called Brain-Pad from claiming its mouth guard can reduce the risk of concussion. The FTC also warned 18 other companies about their products, including a dietary supplement endorsed by New England Patriots quarterback Tom Brady and marketed by his business partner Alejandro Guerrero that promised to protect against concussions by providing a kind of “seat belt” for the brain. The supplement was eventually discontinued. But new products continue to crop up, making claims that go beyond the evidence.

These technofixes face a difficult challenge: the laws of physics. When your head gets yanked around, your brain does too, and it’s nearly impossible to decouple the two. “You can’t put a seat belt around the brain,” says Adnan Hirad, a graduate student at the University of Rochester who has done research on brain injuries in football players.

Concussions happen when the head abruptly accelerates or decelerates, pressing the brain toward the skull—think of how an astronaut gets pushed into their seat when a rocket takes off, or how a passenger gets thrown against the dash if the vehicle makes a sudden stop. With enough force, the brain can slam the inside of the skull, but what happens more commonly is the force of the movement stretches the nervous tissue, impairing the ability of neurons to fire properly, says Steven Broglio, director of the Michigan Concussion Center in Ann Arbor.

Rotation of the head seems to cause more brain stretching and deformation than just straight back-and-forth motions, says Mehmet Kurt, a mechanical engineer at Stevens Institute of Technology. “It’s feasible to think that the more deformation in the brain, the more likely it is to produce a concussion.”

Because there’s no good way to see what’s happening in the brain when someone gets dinged on the head, researchers are left to examine the aftermath. “What’s puzzling about concussions is that the symptoms can vary a lot,” Kurt says. “Most of the time when a player has a concussion, standard medical imaging techniques do not show damage,” he says, and that makes it impossible to diagnose with any one test. Instead, a doctor conducts a clinical exam to assess the patient’s symptoms and makes a judgement call.

And the worry about head injuries isn’t just about concussions, but about chronic traumatic encephalopathy, or CTE, a neurodegenerative disease characterized by memory loss, cognitive problems, and mood disorders, among other things. “It’s close to settled science that CTE is caused by repetitive head blows and not by single concussions,” Hirad says. The current thinking is that even sub-concussive hits can contribute, which means preventing concussions alone won’t eliminate the risk.

Earlier this year, Hirad’s research group reported a stark finding. After a single season of play, collegiate football players ended up with less midbrain white matter than they’d started with. Using accelerometers mounted to the players’ helmets, the scientists observed that the degree of white matter loss correlated with how much rotational acceleration the players’ brains had experienced. The study reinforces the idea that rotational forces are especially risky, Hirad says.