As study limits draw scrutiny

Chris Nowinski is challenging how the NFL presents the evidence for Guardian Caps, bringing a dispute over the padded helmet covers back into public view through a Tuesday interview with Pablo Torre.

The brain injury researcher questioned the league's concussion claims in an October 6 post from Pablo Torre Finds Out. An early Wednesday Pro Football Talk report revisited that criticism.

The disagreement concerns whether the padding caused the reduction observed after the NFL mandate.

A 2025 study in the American Journal of Sports Medicine examined NFL preseason practice concussions from 2018 through 2023, excluding 2020. Its abstract reports a 54%–62% decrease associated with required Guardian Cap NXT use among affected positions. But the smaller analysis of concussions involving helmet-shell impacts found no statistically significant association. The authors said the overall reduction could not be attributed solely to the cap's energy-absorbing effects.

That leaves a more complicated finding than either a guarantee of protection or a blanket conclusion that the equipment has no benefit. The study concerned preseason practices; it does not establish what happens in every game, age group or helmet combination.

The league has defended its interpretation. In Jeff Eisenberg's September 22 Yahoo Sports investigation, NFL health and safety executive Jeff Miller argued that at least part of the observed concussion decline should be attributed to the caps. Nowinski disputed that explanation and warned about a false sense of security. That reporting predates this week's interview.

The study also disclosed NFL-linked funding and affiliations, including NFL chief medical officer Allen Sills among its authors.

The NFL’s current helmet guidance allows players at positions that require Guardian Caps in practice to use one of ten designated helmet models without the cover. The league cautions that its laboratory results should not be extrapolated to college, high school or youth football.