Avenues for Sport-Related Concussion Prevention in High School Football: Effect of Limiting Collision Practices

Context: Football continues to demonstrate the highest rate of sport-related concussion (SRC) in high school athletics. To mitigate the SRC risk, the Michigan High School Athletic Association (MHSAA) implemented rules aimed at reducing the number of collisions occurring in practices.Objective: To estimate the rates of SRC in MHSAA football programs and evaluate progressive limitations to collision practices over 5 consecutive seasons.Design: Retrospective cohort study.Setting: Michigan high school football.Patients or Other Participants: High school (9th-12th grade) football athletes (.99% male) participating in MHSAA-sanctioned events.Main Outcome Measure(s): Designated administrators at each school recorded the total number of participating athletes and SRCs (defined as head injuries resulting from athletic participation that required the student-athletes to be withheld from activity after exhibiting signs, symptoms, or behaviors consistent with an SRC) in the MHSAA injury-surveillance system each season (2015-2016 through 2019-2020). Pro-gressive limitations to collision practices occurred across the study period. We estimated athlete-exposures (AEs) as the total number of players multiplied by the total number of possible practices (11 weeks, 4 days each) or competitions (9 weeks, 1 day each) during each season. Incidence rates and rate ratios (RRs) with 95% CIs were used to compare practice and competition SRCs and each season with the most recent season.Results: A total of 7755 football SRCs were diagnosed across the 5-year period. The overall SRC rate was 8.03 per 10000 AEs (95% CI = 7.85, 8.21). The competition SRC rate (30.13/10 000 AEs) was higher than the practice rate (3.51/ 10 000 AEs; RR = 8.58; 95% CI = 8.19, 9.00). The practice SRC rate was lower in 2017-2018 (RR = 0.86; 95% CI = 0.77, 0.97), 2018-2019 (RR = 0.89; 95% CI = 0.79, 1.0), and 2019-2020 (RR = 0.83; 95% CI = 0.74, 0.94) relative to 2015-2016. Conclusions: We found that the progressive limitations to collision practices were protective against SRCs, as the rate of SRC was lower in the 3 most recent seasons relative to 2015- 2016.