Cumulative Head Impact Burden in High School Football

Abstract

Impacts to the head are common in collision sports such as football. Emerging research has begun to elucidate concussion tolerance levels, but sub-concussive impacts that do not result in clinical signs or symptoms of concussion are much more common, and are speculated to lead to alterations in cerebral structure and function later in life. We investigated the cumulative number of head impacts and their associated acceleration burden in 95 high school football players across four seasons of play using the Head Impact Telemetry System (HITS). The 4-year investigation resulted in 101,994 impacts collected across 190 practice sessions and 50 games. The number of impacts per 14-week season varied by playing position and starting status, with the average player sustaining 652 impacts. Linemen sustained the highest number of impacts per season (868); followed by tight ends, running backs, and linebackers (619); then quarterbacks (467); and receivers, cornerbacks, and safeties (372). Post-impact accelerations of the head also varied by playing position and starting status, with a seasonal linear acceleration burden of 16,746.1g, while the rotational acceleration and HIT severity profile burdens were 1,090,697.7 rad/sec 2 and 10,021, respectively. The adolescent athletes in this study clearly sustained a large number of impacts to the head, with an impressive associated acceleration burden as a direct result of football participation. These findings raise concern about the relationship between sub-concussive head impacts incurred during football participation and late-life cerebral pathogenesis, and justify consideration of ways to best minimize impacts and mitigate cognitive declines.

Similar head impact acceleration measured using instrumented ear patches in a junior rugby union team during matches in comparison with other sports

“…20,21 Additionally, the cumulative impact burden per match and per player per match were analyzed using Kruskal-Wallis 1-way ANOVA with a Dunn's post hoc test for all pairwise comparisons. Although there is no accepted method for quantifying cumulative impact burden, 2 the sum of the linear and rotational accelerations associated with each individual head impact over the course of the study was calculated for all of these parameters.…”

“…11 As well as a higher risk of a concussive event, younger players can also have a prolonged recovery process when compared with adults. 12 In American youth football (6-to 9-year-old players) there was a reported average of 107 impacts per player per season, with an average linear and rotational acceleration of 18g and 901 rad/sec 2 . Most impacts occur during practice (59%) and have a higher magnitude than those recorded in aBBreViatiOnS HITS = Head Impact Telemetry System; IQR = interquartile range; K-D = King-Devick; PLA = peak linear acceleration; PRA = peak rotational acceleration.…”

“…37 Nonhelmeted sports have also used accelerometers to measure impacts in sports participation. Heading the ball by female soccer youths yielded peak accelerations of 63g and 8869 rad/sec 2 . 18 No concussions were reported, 18 as no injury or injury risk was assessed, even though some of the rotational accelerations were within the nominal values for an injury to the head when compared with National Football League data 33 and injury risk tolerance levels.…”

Head-Impact–Measurement Devices: A Systematic Review

“…48,49,64,68,71 Defensive-line players sustained more impacts per session than offensive linemen, offensive-skill players, and defensive-skill players. Defensive-line players also had impacts of greater linear magnitudes than did defensive-skill and offensiveline players.…”

Medical Ethics and School Football

“…5;Gessel, Fields, and Collins 2007;Marar et al 2012;Dompier, Kerr, and Marshall 2015). Nine-to 12-year-old players experience an average of 240 head impacts per season; high school players average 650 head impacts per season (Broglio, Eckner, and Martini 2011;Cobb, Urban, and Davenport 2013;Daniel, Rowson, and Duma 2012). An initial football concussion increases the risk of a subsequent concussion three-or fourfold not simply for the balance of that season but for the following season as well (GoodwinGerberich, Prieste, and Boen 1983, chap.…”