Head Impacts During High School Football: A Biomechanical Assessment

Abstract

Main Outcome Measure(s): Biomechanical variables (linear acceleration, rotational acceleration, jerk, force, impulse, and impact duration) related to head impacts were categorized by session type, player position, and helmet impact location.Results: Differences in grouping variables were found for each impact descriptor. Impacts occurred more frequently and with greater intensity during games. Linear acceleration was greatest in defensive linemen and offensive skill players and when the impact occurred at the top of the helmet. The largest rotational acceleration occurred in defensive linemen and with impacts to the front of the helmet. Impacts with the highestmagnitude jerk, force, and impulse and shortest duration occurred in the offensive skill, defensive line, offensive line, and defensive skill players, respectively. Top-of-the-helmet impacts yielded the greatest magnitude for the same variables.Conclusions: We are the first to provide a biomechanical characterization of head impacts in an interscholastic football team across a season of play. The intensity of game play manifested with more frequent and intense impacts. The highest-magnitude variables were distributed across all player groups, but impacts to the top of the helmet yielded the highest values. These high school football athletes appeared to sustain greater accelerations after impact than their older counterparts did. How this finding relates to concussion occurrence has yet to be elucidated.Key Words: concussions, mild traumatic brain injuries, Head Impact Telemetry System, acceleration Key Points N The mean linear acceleration resulting from impacts recorded during both high school games and practices exceeded that reported at the collegiate level.N Impacts to the top of the head yielded the greatest linear acceleration and impact force magnitude. Coaches must teach proper tackling techniques in order to reduce the risk of concussions and serious cervical spine injuries.

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

“…For the peak LA frequency distribution, both during the games and practice sessions, the range of 10 g ≤ X < 15 g was the most frequent, and the distributions were largely skewed towards low values, supporting previous reports [11][12][13][19][20][21][22][23][24][25] . However, the played over four 15-min quarters in the USA, it is played over four 12-min quarters in Japan, a shorter time period.…”

“…Recently, the development of HITS, which collects impact information from the acceleration sensor attached inside the helmet and the sideline response system, which transmits the data, has made it possible to collect collision data from players on actual fields [9][10][11][12][13][19][20][21][22][23][24][25][26][27][28] . However, HITS only measures LA, and RA had to be estimated 28) .…”

“…In the 2000s, many researchers started to use a headimpact telemetry system (HITS, Simbex, Lebanon NH) equipped with an acceleration sensor installed inside a Riddell (Elyria, OH) helmet to collect real-time headacceleration data during head collisions between American football players [9][10][11][12][13][19][20][21][22][23][24][25][26][27][28] . The data collected by HITS is transmitted to a PC application in real time via a sideline response system (Riddell, Chicago, IL).…”

The Influence of Head Impact Threshold for Reporting Data in Contact and Collision Sports: Systematic Review and Original Data Analysis

“…Nearly three-quarters (74%) of the studies 6-9, 12-16, 20 15 ) and 36ms (HIC 36 ). 8,90 No study reviewed reported the Generalised Acceleration Model for Brain Injury Threshold (GAMBIT) 77,78 or the Head Impact Power (HIP) 79 in their assessment of head impact biomechanics.…”

“…Based on the differences observed in this study, at the 14.4g threshold there could have been as many as 42% of the impacts recorded not being reported. As a result, studies 7,8,[12][13][14][15]20, 27, 33, 94, 107, 115, 119 using impact thresholds above 10g may have removed 2,100 to 206,573 impacts (see Table 2). At the 30g impact threshold it can be estimated that 80 to 85% of impacts were not reported.…”