High school football remains a popular, physically demanding sport despite the known risks for acute brain and neck injury. Impacts to the head also raise concerns about their cumulative effects and long-term health consequences.


To examine the effectiveness of a helmetless tackling training program to reduce head impact exposure in football participants.


A three-year, quasi-experimental, prospective cohort ( #NCTXXX) study.


Honolulu (XXX, XXX) area public and private secondary schools with varsity and junior varsity football.

Patients or Other Participants

Football participants (n=496) ages 14 to 18 years old. Intervention(s) Participants wore new football helmets furnished with head impact sensor technology. Teams employed a season-long helmetless tackling and blocking intervention in Years 2 and 3 consisting of a 3-phase, systematic progression of 10 instructional drills.

Main Outcome Measure(s)

Head impact frequency per athlete exposure (ImpAE), location, and impact magnitude per participant intervention adherence levels (60% and 80%).


An overall regression analysis revealed a significant negative association between ImpAE and adherence (p=0.003, beta=-1.21, SE=0.41). In year 3, a longitudinal data analysis of weekly ImpAE data resulted in an overall difference between the adherent and non-adherent groups (p=0.040 at 80%; p=0.004 at 60%), mainly due to decreases in top and side impacts. Mean cumulative impact burden for the adherent group (n=131: 2,105.84g ± 219.76,) was significantly (p=0.020) less than the non-adherent group (n=90: 3,158.25g ± 434.80) at the 60% adherence level.


Participants adhering to the intervention on at least a 60% level experienced a 34% to 37% significant reduction in the number of head impacts (per exposure) through the season. These results provide additional evidence that a helmetless tackling and blocking training intervention (utilizing the HuTT® program) reduces head impact exposure in high school football players. Adherence to an intervention is crucial for achieving intended outcomes.

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Author notes

We wish to thank Elissa Roblero, MS, ATC, Maddison Cunningham, MA, and Jesse Williams MS, ATC, for their assistance in data collection and analysis. We wish to thank James Dunn, Greg Taguchi, Garrett Gillick, Casey DeAndrade, and Herb Lloyd for their assistance with participant coach training and consultation.