Youth football: How young athletes are exposed to high-magnitude head impacts
CHARLOTTESVILLE, VA (OCTOBER 17, 2017). The majority of football players in the US (70%) are elementary and middle school students. These young athletes enthusiastically put on their gear, learn strategy, acquire skills, and participate in games with their peers. Unfortunately, like their professional counterparts these athletes sometimes get injured. Fairly often they sustain head impacts during tackling and blocking maneuvers. Exposure to head impacts in American football has become a national concern: neurocognitive and brain changes can occur from repeated head impacts, even when no evidence of concussion is found.
To gain a greater understanding of head impacts, researchers from the Department of Biomedical Engineering and Mechanics at Virginia Tech examined exposure to these blows in young athletes, 9 to 12 years of age, during football games and practice drills. Their goal was to determine under what circumstances high-magnitude head impacts (linear or rotational accelerations measuring more than 40g, which are more likely to cause concussions than lower-magnitude impacts) occur and how representative practice activities are of game activities with respect to these head impacts. This type of information can help coaches and league officials make informed decisions in structuring both practices and games to reduce risks in these young athletes.
The researchers focused on head impact exposures in 45 athletes from two youth football teams: Juniors (27 players, mean age 9.9 years) and Seniors (18 players, mean age 11.9 years). The researchers collected biomechanical data and videos during 14 games and 55 practice drills. All youths wore helmets equipped with accelerometer arrays that measure head impacts in terms of acceleration. Each time the arrays recorded a head impact greater than 14.4g, data collection was automatically triggered and the impact data were transmitted wirelessly to a sideline computer. Videos of games and practice activities were recorded to verify the occurrence of a high-magnitude head impact, provide evidence of circumstances surrounding the impact, and record the duration of the activity in which the high-magnitude impact occurred.
To define specific circumstances in which high-magnitude head impacts occur, the researchers characterized these impacts based on 1) the position of the team member who received the head impact, 2) the place in the field where the impact occurred, 3) the cause of the impact, and 4) whether the impact occurred during a game or practice drill.
The accelerometer arrays recorded 7590 head impacts, of which 571 (8%) were of high magnitude. Players in "Back" positions (quarterback, running back, and linebacker positions) sustained more head impacts than players in other positions. These players were more likely to experience high-magnitude head impacts during a tackling activity; players in offensive and defensive line positions were more likely to sustain head impacts during a blocking activity.
Not surprisingly, the more playing time an athlete had, the greater chance that particular youth would sustain a high-magnitude head impact. During games, high-magnitude head impacts occurred more often in the open field–where players in Back positions were often found–than in the line of scrimmage.
The authors found a higher rate of high-magnitude impacts during games than during practice sessions for both teams. Nevertheless, practice sessions occur more frequently than games, and thus subject players to more opportunities to receive head impacts. Twice as many high-magnitude head impacts occurred in Senior team members than in Junior team players. The researchers state that differences in age and weight alone cannot explain this difference. Video data indicated that practice intensity or coaching style may be another factor in this difference. This factor could be a focus of future studies.
When asked about the study, senior author Steven Rowson, PhD, said, "This study builds on a growing body of research on head impact exposure in youth football. These studies are important because they allow you to make data-driven decisions when structuring changes to practice in football to reduce exposure to head impact. Purposeful reduction of exposure means less opportunity for concussion and a reduction in any potential consequences of cumulative exposure."
Detailed findings of this study can be found in the following article: Campolettano ET, Gellner RA, Rowson S. High-magnitude head impact exposure in youth football. Journal of Neurosurgery: Pediatrics, published online, ahead of print, October 17, 2017; DOI: 10.3171/2017.5.PEDS17185 (http://www.thejns.org/doi/full/10.3171/2017.5.PEDS17185).
Funding: Research reported in this paper was funded by National Institute of Neurological Disorders and Stroke Grant No. R01NS094410.
Disclosure: The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
For additional information, please contact: Ms. Jo Ann M. Eliason, Communications Manager, Journal of Neurosurgery Publishing Group, One Morton Drive, Suite 200, Charlottesville, VA 22903. Email: [email protected] Phone: 434-982-1209
The Journal of Neurosurgery: Pediatrics is a monthly peer-reviewed journal focused on diseases and disorders of the central nervous system and spine in children. This journal contains a variety of articles, including descriptions of preclinical and clinical research as well as case reports and technical notes. The Journal of Neurosurgery: Pediatrics is one of four monthly journals published by the JNS Publishing Group, the scholarly journal division of the American Association of Neurological Surgeons. Other peer-reviewed journals published by the JNS Publishing Group each month include the Journal of Neurosurgery, Neurosurgical Focus, and the Journal of Neurosurgery: Spine. All four journals can be accessed at http://www.thejns.org.
Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 8,300 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada, or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the brain, spinal column, spinal cord, and peripheral nerves. For more information, visit http://www.AANS.org.
Jo Ann M. Eliason