title: Head impact exposure in youth football: elementary school ages 9-12 years and the effect of practice structure.
abstract: Head impact exposure in youth football has not been well-documented, despite children under the age of 14 accounting for 70% of all football players in the United States. The objective of this study was to quantify the head impact exposure of youth football players, age 9-12, for all practices and games over the course of single season. A total of 50 players (age = 11.0 ± 1.1 years) on three teams were equipped with helmet mounted accelerometer arrays, which monitored each impact players sustained during practices and games. During the season, 11,978 impacts were recorded for this age group. Players averaged 240 ± 147 impacts for the season with linear and rotational 95th percentile magnitudes of 43 ± 7 g and 2034 ± 361 rad/s(2). Overall, practice and game sessions involved similar impact frequencies and magnitudes. One of the three teams however, had substantially fewer impacts per practice and lower 95th percentile magnitudes in practices due to a concerted effort to limit contact in practices. The same team also participated in fewer practices, further reducing the number of impacts each player experienced in practice. Head impact exposures in games showed no statistical difference. While the acceleration magnitudes among 9-12 year old players tended to be lower than those reported for older players, some recorded high magnitude impacts were similar to those seen at the high school and college level. Head impact exposure in youth football may be appreciably reduced by limiting contact in practices. Further research is required to assess whether such a reduction in head impact exposure will result in a reduction in concussion incidence.
authors.affiliation: School of Biomedical Engineering & Sciences, Virginia Tech-Wake Forest University, 440 ICTAS Building, Stanger St., Blacksburg, VA, 24061, USA.
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Cobb
authors.forename: Jillian E
authors.initials: JE
authors.lastname: Urban
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Davenport
authors.forename: Steven
authors.initials: S
authors.lastname: Rowson
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Duma
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Maldjian
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Whitlow
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Powers
authors.forename: Joel D
authors.initials: JD
authors.lastname: Stitzel
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D002648:Child; D006259:Craniocerebral Trauma / Q000503:physiopathology / Q000517:prevention & control*; D005538:Football / Q000293:injuries*; D019416:Head Movements / Q000502:physiology; D006260:Head Protective Devices; D006801:Humans; D012399:Rotation; D013686:Telemetry