Age-related differences in head impact exposure of 9-13 year old football players

While more than two-thirds of football players are under the age of 14, little biomechanics research has been conducted to quantify head impact exposure for players in this age range. The objective of this study was to quantify head impact exposure and the influence of age for 9-13 year old football players. Kinematic data from over 4400 head impacts were collected from 25 youth football players on two teams for one season using in-helmet accelerometers. The 50th and 95th percentile magnitudes for linear and rotational head acceleration and the number of impacts sustained were determined for each player. Comparisons were made for each metric by team and by player age. Players on the 9-11 year old team sustained an average of 154 ± 126 impacts with a 95th percentile linear acceleration magnitude of 40 g. On the 10 to 13 year old team, players sustained an average of 193 ± 158 impacts with a 95th percentile linear acceleration magnitude of 47 g. Players on the older team sustained slightly more and higher magnitude impacts than those on the younger team. These differences in head impact exposure were not significant due to large variation between players within each team.