Head impact exposure in youth football: elementary school ages 7-8 years and the effect of returning players.

Objective: To provide data describing the head impact exposure of 7- to 8-year-old football players.
Design: Head impact data were collected from 19 players over the course of 2 seasons using helmet-mounted accelerometer arrays.
Setting: Data were collected from 2 youth football teams in Blacksburg, VA, spanning 2 seasons.
Participants: A total of 19 youth football players aged 7-8 years.
Independent Variables: Type of session (practice or game) and the player's experience.
Main Outcome Measures: Head impact frequency, acceleration magnitude, and impact location for games, practices, and the season as a whole were measured.
Results: The average instrumented player sustained 9 ± 6 impacts per practice, 11 ± 11 impacts per game, and 161 ± 111 impacts per season. The average instrumented player had a median impact of 16 ± 2 g and 686 ± 169 rad/s and a 95th percentile impact of 38 ± 13 g and 2052 ± 664 rad/s throughout a season. Impacts of 40 g or greater tended to occur more frequently in practices than in games, and practices had a significantly higher 95th percentile impact magnitude than games (P = 0.023). Returning players had significantly more impacts than first time players (P = 0.007).
Conclusions: These data are a further step toward developing effective strategies to reduce the incidence of concussion in youth football and have applications toward youth-specific football helmet designs.