The key to reduce subconcussive head impacts in U.S. high school football is to look inside the practice drills and intensities, according to a new study by IU School of Education and IU School of Public Health faculty.

The study, recently published in PLOS ONE, is a continuation of research the cross-university team has done on subconcussive hits, or hits below the concussion threshold. The team used sensor-installed mouthguards and monitored magnitude and frequency of head impacts in 24 Bloomington High School-North football players throughout the 2019 football season. Researchers combined mouthguard data and film analysis to examine how many head impacts, and to what extent of magnitude, football players are experiencing during each level of contact, and whether there are differences in head impact exposure between various position groups.

The risk/benefit ratio of American football in adolescents has been debated over the past decade. “Some argue that football provides millions of kids opportunity to engage in physical activity while teaching the value of teamwork, comradery and respect, but others caution against the risks of concussion, subconcussive head impact exposure and potential long-term outcome”, said principal investigator Keisuke Kawata, an Assistant Professor at the School of Public Health.

Scientists, engineers and policymakers have come together to promote a safer football environment with countless rule changes and improvement in equipment. “These efforts seemed to reduce concussion risks and severe injury like skull fracture, but subconcussive impact exposure is not so simple,” Kawata said.

Having played football professionally and coached at various levels, Jesse Steinfeldt, a co-author of the paper and an Associate Professor at the School of Education, thought that head impact exposure may be tightly linked to the intensity of practice drills. Steinfeldt explained, “In 2014, USA Football, a governing body for amateur American football, categorized practice drills into five levels of contact ranging from air, bags, control, thud to live, where live is the highest intensity and air is the lowest. We were wondering whether this levels-of-contact guideline is influencing head impact exposure.”

A total of 6016 head impacts were recorded during five levels-of-contact in 24 football players, resulting in a median of 203 hits in a season. “We first identified that the higher the drill intensity, like live, thud and control drills, more frequent head impacts occurred,” said Kyle Kercher, the first author of the paper and a Ph.D. student at the School of Public Health. Kercher further explained, “Head impact exposure was similar between position groups in all drills and so as average magnitude of head impact. Most head impacts were in a lower range of 18 to 23 g-force. When we start diving deeper into the numbers, we found some high magnitude hits such as 100 g-force were buried inside each drill. These high magnitude hits were most prevalent in live followed by thud, but very few in control, bags and air drills. This study is innovative because it doesn’t just quantify head impacts, it quantifies them within a framework of USA Football’s guideline that was designed to be used by coaches attempting to teach the game safety.” 

Jon Macy, co-author and Associate Professor at the School of Public Health, sees the results as very encouraging, as coaches at all levels of football could potentially be trained on how to properly incorporate the levels-of-contact guideline into their practice plans: “Doing so at the middle school level, for example, provides additional years of reduced head impact burden for players and prepares them for high school football,” said Macy.

The finding from this study was particularly meaningful to Steinfeldt. “I wear a lot of Perspective Hats, if you will, as a football coach, researcher, Sport Psychologist, former football player, and perhaps most importantly, as a parent of high school and soon-to-be college football players. This study can help provide a better empirical understanding of what football is, what we need to do to make it safer and how data-driven policies can be implemented to allow America’s biggest participation sport to continue to positively influence the lives of the millions of kids who play it.” 

In closing, Kawata shared his investigative team’s next step: “This study is an excellent first step towards promoting safer football environment while keeping the fun of football intact. Players in this high school sustained reduced head impacts compared to other high schools that do not incorporate the levels-of-contact guideline, but this high school still won a conference championship. This is encouraging. We will be expanding the study to multiple high schools starting from the 2021 season. This large-scale longitudinal study will also include many cutting-edge neurologic assessments. Using holistic approach, we aim to answer questions like how many hits are safe or unsafe during a high school football career.”