Anthropometrics and maturity status: A preliminary study of youth football head impact biomechanics

Context: There is a paucity of head impact biomechanics research focusing on youth athletes. Little is known about how youth subconcussive head impact tolerances are related to physical size and maturation. Objective: To examine the effects of age, anthropometric and maturational status variability on head impact biomechanics. Design: Cross-sectional. Setting: Outdoor youth football facilities in South Carolina. Participants: Thirty-four male recreational youth football players, 8 to 13 yrs. Interventions: Categorized by CDC standards, independent variables were: age, height, mass, BMI, and estimated peak height velocity (PHV). Participants wore a designated head impact sensor (xPatch) on their mastoid process during practices and games. Main outcome measures: Linear acceleration (g) and rotational acceleration (rad/s(2)). Results: Boys in the older age category had a greater linear (F = 17.72; P < 0.001) and rotational acceleration (F = 10.74; P < 0.001) than those in the younger category. Post-PHV boys had higher linear (F = 9.09, P = 0.002) and rotational (F = 5.57, P = 0.018) accelerations than those who were pre-PHV. Rotational, but not linear acceleration differed by height category with lowest impacts found for the tallest category, whereas both linear and rotational accelerations by mass differences favored average and heavy categories. BMI overweight boys, had the greatest linear (F = 5.25; P = 0.011) and rotational acceleration (F = 4.13; P = 0.260) means. Conclusion: Post-PHV boys who were older, taller and had longer legs, but who were not heavier, had higher impacts perhaps due to the type of impacts sustained. Taller boys' heads are above their peers possibly encouraging hits in the torso region resulting in lower impact accelerations. Obese boys did not have sequential results compared to boys in the other BMI categories probably due to league rules, player position, and lack of momentum produced.