There are growing calls for a fundamental change in the training systems for school-age American footballers after research found that players suffered far more head collisions in practice than in a game itself.
Researchers from Wake Forest School of Medicine and the University of Texas Southwestern in Dallas, Texas, examined the frequency and severity of head impacts experienced by youth American football players and how exposure to head impacts changed from one year to the next in returning players.
It comes amid ongoing liability issues over the long-term impacts of head injuries caused by playing the game with a significant number of professional players seeking to bring legal action against the sport’s governing body for head injuries sustained during their playing careers and the long term damage they have caused. There are similar moves in the United Kingdom over the long term head injuries caused to professional rugby union players.
The latest study compared the resulting data with findings on neuroimaging studies obtained over consecutive years in the same athletes. The comparison demonstrated a significant positive association between changes in head impact exposure (HIE) metrics and changes in abnormal findings on brain imaging studies.
The study found that in one football season, youth football players (10–13 years of age) can sustain between 26 and 1003 head impacts, and high school players can sustain between 129 and 1258 head impacts. Fortunately, most of these impacts do not result in concussions. In fact, most of these subconcussive impacts do not produce any acute signs or symptoms attributed to concussions.
“Nevertheless, there is concern that, over time, repetitive subconcussive impacts may cause damage to contact-sport athletes’ brains,” added the report. “This is particularly of concern when we are speaking of young athletes, who have many years ahead of them in their sport and in their lives.”
To examine changes in head impact exposure (HIE) from year to year, the researchers focused on a group of 47 athletes who participated in youth football for two or more consecutive years sometime between 2012 and 2017. The athletes played on a variety of teams. All wore football helmets outfitted with the Riddell Head Impact Telemetry System, which measures linear and rotational head accelerations that occur during a head impact. The outfitted helmets were worn during all football sessions—both practices and games. Biomechanical data on head impacts were transmitted in real time via radio waves to a sideline data collection field unit for later analysis. Altogether, the data covered 109 football athlete–seasons with 41,148 head impacts. Despite the large number of head impacts, none of the 47 youth athletes sustained a clinically diagnosed concussion during the study period.
The study found:
- HIE varied among individual athletes from one season to the next. Increases and decreases in HIE across three consecutive seasons in individual youth football players were observed; the changes were not significant from one season to the next.
- Trends in DTI imaging changes varied among individual athletes from one season to the next. Increases and decreases in the number of abnormal voxels on DTI from the first to second season were identified in individual players.
- The amount of HIE an athlete experienced in football, particularly in practice, was associated with the amount of change in neuroimaging metrics. Positive associations between changes in abnormal voxels on DTI and the number of head impacts per practice session, 50th percentile impacts per practice session, and 50th percentile impacts per session overall (including both practice and game sessions) between consecutive seasons (seasons 1 and 2) were found.
Because of the significant correlation between changes in HIE metrics and changes in the number of abnormal voxels on DTI between consecutive seasons, the researchers called for a reduction in the number and frequency of head impacts, particularly those occurring during practice sessions, when the majority of head impacts occur.
“We believe this action may reduce the number of abnormal imaging findings in youth football athletes from one football season to the next,” the study said.
Dr. Jillian Urban, Assistant Professor at Wake Forest School of Medicine, added: “Our findings further support ongoing efforts to reduce the number of head impacts in football practices. In an upcoming study, we plan to engage stakeholders in the youth football community to develop and test practical solutions informed by the biomechanical data we collect on field to reduce head impacts in practice.”
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