Head impact exposure in collegiate football players

Abstract

In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in head impact exposure by player position. A total of 314 players were enrolled at three institutions and 286,636 head impacts were recorded over three seasons. The 95th percentile peak linear and rotational acceleration and HITsp (a composite severity measure) were 62.7g, 4378 rad/s2, and 32.6, respectively. These exposure measures as well as the frequency of impacts varied significantly by player position and by helmet impact location. Running backs (RB) and quarter backs (QB) received the greatest magnitude head impacts, while defensive line (DL), offensive line (OL) and line backers (LB) received the most frequent head impacts (more than twice as many than any other position). Impacts to the top of the helmet had the lowest peak rotational acceleration (2387 rad/s2), but the greatest peak linear acceleration (72.4 g), and were the least frequent of all locations (13.7%) among all positions. OL and QB had the highest (49.2%) and the lowest (23%.7%) frequency, respectively, of front impacts. QB received the greatest magnitude (70.8g and 5428 rad/s2) and the most frequent (44% and 38.9%) impacts to the back of the helmet. This study quantified head impact exposure in collegiate football, providing data that is critical to advancing the understanding of the biomechanics of concussive injuries and sub-concussive head impacts.

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.…”

“…Football. Collegiate football athletes sustained 420 to 1177 impacts, 48,55 with 9.4 impacts per session 49 at a median linear magnitude of 19g 50 and average 73 Linear magnitudes averaged 26g, 71 with a median of 22g. 74 Angular magnitudes averaged 71,72 1627 to 1694 rad/s 2 and had a median value 74 of 973 rad/s 2 .…”

“…73 Whereas quarterbacks sustained the fewest overall impacts, they had the greatest linear magnitudes, and tight ends, running backs, and linebackers had the greatest angular values. 48,71 Ice Hockey. Collegiate ice hockey players sustained 170 to 347 impacts per season.…”

Impact on the head during collisions between university American football players - focusing on the number of head impacts and linear head acceleration -

“…However, Broglio et al set the cut-off value at 15 g 20) , and the study performed by value. In this study, we removed the data with a peak LA less than 10 g. In previous studies as well, the data with a peak LA of 10 g or less were removed because these data included noncontact motions such as quick stand-up, running, and jumping 41) . However, the data with a peak LA less than 10 g amounted to 9.7% of the total number of impacts.…”

Chronic traumatic encephalopathy: A paradigm in search of evidence?

“…He further played on the offensive line, a position that suffers the most frontal impacts of all positions in the sport. 97 He retired after several years in the NFL, having also played for 5 years at a major Division I university. A conservative estimate, based indirectly on accelerometer studies, is that he suffered as many as 10 000 head impacts exceeding 10 times g, over the course of just his collegiate and professional careers.…”