"The biggest surprise was the extent of the data, not just the trend of the data," said Dr. Michael A. McCrea, the study's lead author and a professor of neurosurgery at the Medical College of Wisconsin, where he is co-director of the Center for Neurotrauma Research.
"Most people, scientists or not, are aware that there's more full-contact activity in the preseason than in the regular season, so I'm not sure the trend of that finding is a surprise," he continued. "But maybe the magnitude of it."
In an editorial also published in JAMA Neurology on Monday, two other experts on brain injuries described the study's findings as "shocking," particularly given statistics about concussions and head impact exposure, known as HIE, during contractually regulated practices in the NFL.
Professional teams may hold no more than 14 padded practices during the regular season. In the NFL's 2019 regular season, less than 7% of concussions happened during practices, according to league data.
"Concussions in games are inevitable, but concussions in practice are preventable," the experts, Dr. Robert C. Cantu and Christopher J. Nowinski, who were not authors of the McCrea-led study, wrote in their editorial. "Practices are controlled situations where coaches have almost complete authority over the HIE risks taken by players."
Even as they acknowledged that the NCAA had issued recommendations and pressed for wider changes, they noted tartly that "guidelines are not rules."
The NCAA, which draws its authority from its member schools, did not immediately comment Monday.
In a speech in January, Mark Emmert, the NCAA's president, said the association had "made wonderful strides around concussion protocols," perhaps a reference to a 2015 mandate that every school in a Power Five conference annually submit its concussion guidelines for review by a national committee. (That procedure has been waived during the coronavirus pandemic.)
During his address at the NCAA convention, Emmert, without elaboration, urged adding "some teeth to our health and safety protocols" and said there should be a system that "holds each other accountable for the commitments we make to promote and advocate and conduct those protocols."
But the NCAA's legislative process is grueling, and few sports enterprises are as sprawling and disjointed as Division I college football. Although the NCAA caps practice time and enforces rules around matters like transfers and recruiting, the conferences that play football within Division I have enormous power and set policies that can vary from one league to the next.
In 2016, for instance, the Ivy League — which plays in the Football Championship Subdivision, not the Football Bowl Subdivision that draws most of the money and attention — banned full-contact hits during all regular-season practices. The rule stands alone, the editorial noted, almost five years later.
The NCAA itself has often stuck with what it describes as "recommendations" to combat concussion risks, including that three days of practice each week during the regular season should involve no or minimal contact. The NCAA's approach, the study's authors asserted, "have had a limited effect in reducing preseason concussion incidence."
The findings that were published Monday were long in the making. In the study, conducted at six Division I schools that participate in a research consortium partly funded by the NCAA and the Pentagon, 658 football players wore helmets outfitted with accelerometers.
By the end of the 2019 season, when the study concluded after recording more than 528,000 head impacts across five seasons, 68 of the monitored players had suffered concussions. The researchers tracked players at Air Force, Army, North Carolina, UCLA, Virginia Tech and Wisconsin. Spring practices were not included, McCrea said.
Crucially, researchers have found variances in head impact exposures among individual players, even among teammates playing the same position.
"Certain teams practice different than other teams, and certain players play different than other players," McCrea said.
Beyond any overarching strategies that could emerge, he said, athletes should engage in more localized efforts to try to reduce risks.
"There's shared responsibility here: on the scientists who produce the evidence, on policymakers, on institutions and coaches and players," he said. "I think we all have a responsibility."