Football players receive concussions because of cumulative hits to the head, as opposed to just one single blow, according to researchers at Purdue University. During the course of a two year study, scientists examined football players from Jefferson High School in Lafayette, Indiana, and analyzed 21 players in the first season, and 24 in the second season, including 16 repeating players.

Football helmets used during the season were equipped with attached sensors, which were compared with brain-imaging scans and cognitive tests performed before, during, and after each season.

“The most important implication of the new finding is the suggestion that a concussion is not just the result of a single blow, but it’s really the totality of blows that took place over the season,” said Eric Nauman, an associate professor of mechanical engineering and an expert in central nervous system and musculoskeletal trauma. “The one hit that brought on the concussion is arguable the straw that broke the camel’s back.”

Shifts were noticed in regions of the brain that have been linked with chronic traumatic encephalopathy (CTE), a progressive degenerative disease found in people who suffer multiple concussions and other types of head injuries.

“This is still circumstantial evidence, but it suggests that whether you are concussed or not your brain is changing as a result of all these hits, and the regions most affected are the ones that exhibit CTE,” Nauman said.

“Now that we know there is definitely a buildup of damage before the concussion occurs, ultimately, there is hope that we can do more to prevent concussions,” he concluded.