Head Injury in Youth Football
Plain Language Summary – “Brain Trauma Exposure for American Tackle Football Players 5 to 9 and 9 to 14 Years of Age”
NOCSAE awarded research grants to help expand the scientific background for a possible youth helmet standard. One of these studies, “Brain Trauma Exposure for American Tackle Football Players 5 to 9 and 9 to 14 Years of Age” is by a team of researchers who found that head impacts in younger players can be more serious because they have weaker necks and proportionally larger heads. Because of this it is difficult for them to control their bodies during a fall to the ground and on the recoil after helmet-to-helmet impacts. The following is a summary of how the research team conducted their investigation and what they concluded.
Who were the researchers?
J. Cournoyer, C. Karton, D. Koncan, M.D. Gilchrist, R.C. Cantu, and T.B. Hoshizaki.
How was this study done?
This study involved three stages of analysis: video analysis, laboratory reconstructions, and finite element modeling of head impacts from youth football games.
Video
Sixty football games were video taped and were divided into two categories for ages 5 to 9 and 9 to 14-year-olds. There were 30 teams in each age group. Head impacts were documented for 7 players on the team. The players were one quarterback, one running back, one wide receiver, one offensive lineman, one defensive lineman, one linebacker, and one defensive back. For each verified head impact that was observed on the video, the researchers documented where the impact occurred on the head, and how it occurred, such as head-to-head or head-to-ground. The researchers then visually classified the velocity of the impact from very low to high.
Laboratory Reconstructions
Following the video analysis of the head impacts, the researchers simulated the impact scenario in the laboratory. For these simulations they chose the head-to-head, head-to-ground, and head-to-shoulder impacts as these made up over 85% of the impacts seen on the videos. They used the small-sized NOCSAE headform for both age groups, fitted with a youth-sized football helmet. Head-to-ground impacts were simulated using the free fall drop test and head-to-head and head-to-shoulder simulations were completed using a pendulum test.
Finite Element Modeling (FEM)
The third component of the study involved using finite element modeling, which is a computer derived model of the brain that allows the researcher to enter an impact magnitude (from the laboratory reconstructions) into the model to determine peak Maximum Principal Strain. MPS is used to classify the severity of a head impact.
Concepts
More About FEM
Finite Element Modeling is a computational technique used in brain injury research (and other types of investigations) to simulate and analyze the mechanical behavior of the brain and its tissues under various conditions, such as impact or acceleration. It breaks down complex structures, like the brain, into smaller, simpler elements (finite elements) that can be analyzed mathematically. It helps us understand how brain tissue behaves under stress, including deformation (changes in shape or structure caused by pressure) and strain (stretch). This allows researchers to model the physical responses of brain tissues to different forces and predict injury risk.
More About MPS
Maximum Principal Strain is a threshold calculation for measuring the highest level of deformation (changes in shape or structure caused by pressure) that a material, such as brain tissue, experiences under stress. It is an important concept in brain injury research because it helps predict how and when brain tissue will fail or sustain damage due to forces like acceleration (sudden movements) and impact.
What were the results of the study?
In the group of 5 to 9-year-olds, the researchers recorded 590 head impacts in 30 games. In the group of 9 to 14-year-olds, researchers verified 805 head impacts. This difference in the number of impacts between groups is not statistically significant. In both age groups, most impacts were a result of head-to-head contact, and the next highest number were head-to-ground impacts.
The majority of impacts in both age groups had MPS values classified as low. While impacts in this category may not be linked to diagnosed concussions, they are important to note because they are linked to injuries that lead to changes in brain structures and cognitive impairments that may not have symptoms.
More impacts in the moderate-range category occurred in the younger group than in the older group. Moderate-range MPS level impacts have been associated with concussions. This higher number of moderate-range impacts appears to be due to the relative inability of younger kids to control the the motion of their heads during an impact event. Further, because the added weight of a helmet adds to this problem, the researchers concluded that younger athletes may benefit from a smaller and lighter helmet.
In both age categories most of the head impacts occurred to running backs, followed by defensive line players, and then linebackers. Impact events were similar for both age groups as well. Most impacts were a result of head-to-head followed in number by head-to-ground.
Laboratory reconstructions of the impacts showed that measurements of peak linear and rotational accelerations were both lower than the range used in testing helmets to the current football helmet standard. Because of this, researchers suggested lowering the pass/fail testing criteria for youth helmets to more accurately capture the magnitudes of impacts experienced by younger players on the field.
Ultimately the findings reported in this study helped support the development of a youth-specific helmet standard.
Where can I learn more about this study?
Read the full study: “Brain Trauma Exposure for American Tackle Football Players 5 to 9 and 9 to 14 Years of Age – PDF.”