Abstract
Background:
With growing concern about long-term effects of head injuries from contact sports, understanding differences in impact frequency and magnitude across age groups is critical. Youth athletes may face heightened risks due to developmental factors, yet the relationship between level of play and HIE remains unclear. Our systematic review aims to compare head impact exposure (HIE) characteristics between youth (defined as younger than 14 years) and college-level football players using accelerometers, which are placed on headgear to measure acceleration forces during impacts.
Hypothesis:
We hypothesized that while youth athletes may sustain fewer impacts than collegiate players over the season and per session, both groups could exhibit comparable acceleration magnitudes.
Methods:
A systematic review search, following guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), was conducted in PubMed, Embase, and Scopus for studies from 2015-2024 that used accelerometer-based sensors on helmets or headgear to quantify HIE in youth or college-level football athletes, with impacts defined as acceleration events exceeding a 10-15g threshold. Study variables included cohort age, length of study period, type of accelerometer used, frequency of impacts during practice and competition, and median and 95th percentile linear and rotational acceleration.
Results:
29 studies met inclusion criteria, representing 1,742 youth athletes (ages 6–14) and 3,850 collegiate athletes (ages 17–23). On average, collegiate players sustained more impacts per season than youth in both practice (472.11 vs. 113.03) and combined settings (449.04 vs. 228.04). However, youth athletes experienced an amount of impacts per individual game comparable to collegiate players (9.97 vs. 9.78). Median linear acceleration values were similar across age groups during the overall season (youth: 18.6g; college: 20.7g), as were 95th percentile values (46.4g vs. 47.7g). For rotational acceleration, youth athletes had higher seasonal median (1144.9 vs. 964.0 rad/s²) and 95th percentile values (2929.7 vs. 2072.2 rad/s²).
Conclusion:
Despite lower cumulative exposure, youth football players experience similar impacts per game and occasionally higher magnitudes compared to collegiate players. Given their developmental vulnerability, these findings highlight the need for age-specific safety protocols (i.e., restructured seasons, practice modifications, biomechanical interventions such as compression collars) to mitigate long-term neurodegenerative risks and better protect pediatric athletes during a critical period of brain maturation.