On-field Characteristics and Head Impact Magnitude in Youth Tackle Football

Abstract Purpose This study determined the effect of video-verified collision characteristics on head impact magnitudes in male youth tackle football. Methods Participants (n=23, age=10.9±0.3yrs, height=150.0±8.3cm, mass=41.6±8.4kg) wore Triax Sim-G sensors throughout the Fall 2019 season. Ten filmed games were used to identify nine different collision characteristics: mechanism, preparedness, head direction, struck versus striking activity, stance, play type, closing distance, penalty, and quarter. Random-effects general linear models and Cohen’s d effect sizes were used to examine differences in log-transformed peak linear (PLA; g) and rotational (PRA; rad/s 2 ) accelerations across characteristics. The 10 games produced 533 total video-verified impacts and 23.2±7.2 impacts per athlete. Results PLA (p range:0.107-0.923) and PRA (p range:0.057-0.768) did not differ across characteristics. Struck players (3,370rads/s 2 , 95%CI=2,986-3,808) had a small effect for higher PRA compared to striking players (3,037rads/s 2 , 95%CI=2,713-3,404, d=0.251), but negligible effect for simultaneous struck-striking players (3,340 rad/s 2 , 95%CI=2,945-3,792, d=0.018). Fourth quarter impacts (3,490rads/s 2 , 95%CI=3,083-3,951) had a small effect for higher PRA compared to first (2,945rads/s 2 , 95%CI=2,596-3,337, d=0.404), second (3,196rads/s 2 , 95%CI=2,832-3,604, d=0.219) and third quarters (3,241rads/s 2 , 95%CI=2,841-3,699, d=0.144). Conclusion Youth tackle football characteristics did not significantly affect head impact magnitudes during games. More research is needed to explore additional factors that could be modified for sport safety rather than mitigating impact mechanism.