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CARE Consortium: Comparison of head impact exposure between concussed football athletes and matched controls

Head impact exposure, not merely the force of a given impact, may have a higher correlation with eventual concussion

While the understanding of sport-related concussion and its short- and long-term consequences has continued apace, what role might exposure to repetitive head impacts play in brain health and vulnerability to injury? Brian Stemper, an associate professor of neurosurgery at the Medical College of Wisconsin, and a team of researchers relied on data captured by Head Impact Telemetry Systems in use at six Division I varsity football programs as part of the NCAA-Department of Defense Concussion Assessment, Research and Education Consortium study to determine how exposure to contact might affect concussion vulnerability. The devices, mounted in each student-athlete’s helmet, measure linear and rotational acceleration. In all, Stemper and his team collected data from 511 college football players over the course of the 2015-17 football seasons. The examination was published in the Annals of Biomedical Engineering.

What did the study find?

More than 400,000 head impacts and 50 concussions were chronicled during the study. For each concussion suffered, researchers were able to identify which impact triggered the concussion via the HIT System data and video analysis. Each of the concussed athletes was matched against an uninjured control player from the same position and team. Of the concussed athletes, 72% experienced more head impact exposure either on the date of the injury or for the season up to the injury when compared with their matched controls. Additionally, the data demonstrated a wide range for the magnitude of head impacts that resulted in concussion. Most of the impacts that triggered an injury occurred at accelerations typically considered to be lower risk. More than half of the concussions were associated with head impacts at acceleration levels indicative of less than 1% risk of injury according to statistical models developed from previous research.

What are the implications?

Exposure to impacts, not merely the force of a given impact, appeared to have a higher correlation with eventual concussion. This suggests that a high magnitude of exposure, even to hits that produce lower levels of head acceleration, may have a priming effect. “This unique analysis provided some evidence for the role of repetitive head impact exposure in the onset of concussion,” the authors wrote.

What’s next?

This head impact analysis could be used to inform future rules governing how much contact student-athletes can be exposed to, but further study is needed. “While these trends require further validation, the clinical implication of these findings supports the contemporary trend of limiting head impact exposure for college football athletes during practice activities,” the study noted. Additionally, future work could further account for the differences in contact and exposure levels between starters and reserve players.