Does heading the ball in football really affect the brain?

Compiled by: Gong Zixin

At a football game

Pass, shoot or clear with your head

It is a routine action that does not usually cause concussions

However

A new study from the University of British Columbia shows

Even a slight header

It also affects the brain

The study, published in the Annals of Biomedical Engineering, shows that the impact of heading a ball causes a momentary slowing of brain activity, producing brain waves that are typically associated with sleep and sleepiness. In the experiment, eight healthy adults controlled heading of a soccer ball with forces comparable to those typically seen in competition. Participants performed simulated soccer heading at two light levels (6g, 4rad/s and 10g, 8rad/s) and three directions (frontal, left oblique, right oblique) while wearing EEG sensors and a custom-made mouthguard. Throughout the experiment, synchronized head kinematics and brain activity measurements were made using an inertial measurement unit (IMU) and EEG electrodes.

Lead researcher Lyndia Wu, PhD, assistant professor of mechanical engineering in the College of Applied Sciences, who studies sports-related injuries, said that immediately following the impact, participants experienced a brief but statistically significant increase in delta brain waves. "Delta waves are low-frequency waves that are associated with drowsiness and sleep. When this sleep-like delta activity occurs during wakefulness, it can disrupt information processing and lead to a lapse in focus. For athletes, this could lead to decreased concentration after an impact." Lyndia noted that there is growing concern about the effects of repeated exposure to such mild head impacts on the brain. This study is unique because it was able to measure what happens in the brain immediately after a head impact. There is a growing body of research on subconcussions, but most studies can only measure impacts after a game or season, which does not help understand the effects of individual impacts and how they accumulate. The study also investigated how the severity and direction of the impact affected brain activity. These changes were statistically significantly higher for 10g impacts compared to 6g impacts in certain areas, and oblique impacts led to an increase in contralateral delta power. That is, more intense impacts resulted in a greater increase in delta waves, while oblique impacts resulted in greater activity on the other side of the head.

Additionally, resting-state measurements did not show any cumulative effects, meaning that brain activity quickly returned to normal for most participants, suggesting no long-term effects. However, some people showed more pronounced changes, suggesting individual differences in brain responses. These findings highlight the need for personalized safety measures and further research into individual responses to impacts, especially in sports such as football and rugby where head impacts are frequent. The researchers note that the results suggest that even mild head impacts in football can lead to immediate, transient neurophysiological changes. This study advances the understanding of how mild head impacts affect brain function and illustrates the importance of ongoing research to protecting the health of athletes. It also paves the way for further research into the effects of more frequent, repeated impacts, and how rest time between impacts affects recovery.