A recent study on soccer players found that heading a soccer ball can impair cognitive function and disrupt the organization of neural processes associated with this activity. The findings were published in Frontiers in Human Neuroscience.
Soccer heading is a technique where players use their foreheads to strike and direct the ball. It is commonly used for passing, scoring goals, and defensive clears. Effective heading requires precise timing, positioning, and the ability to generate power and accuracy with the head. Players often practice heading through drills that enhance their ability to judge the ball’s flight and impact.
However, recent studies suggest that repeated impacts from heading a soccer ball are associated with an increased risk of neurodegenerative diseases later in life. Soccer players, except for goalkeepers, are 3.5 times more likely to suffer from neurodegenerative diseases compared to goalkeepers and the general population. The risk is five times higher for players in defensive positions, where heading is more frequent. A recent study showed that regular soccer heading for just two weeks can increase neurological symptoms.
Study author Johnny V. V. Parr and his colleagues aimed to explore how a short bout of repetitive soccer heading affects the brain’s control of movement and the communication between the cortex and muscles. They compared individuals practicing real soccer heading with those performing the same task in virtual reality, where no physical impact occurred.
The researchers hypothesized that the group practicing heading in virtual reality would show improved accuracy and precision of movements, accompanied by increases in specific brain activity indicators measured through electroencephalography (EEG) and electromyography (EMG). These improvements were expected to be absent or reduced in the group practicing real soccer heading.
The study involved 60 soccer players, equally divided between males and females, with an average age of 24 years. Most were recreational players, while six were semi-professional. The majority were midfielders or defenders, and none reported a prior history of concussions.
Upon arrival at the lab, participants first completed the King-Devick test, a cognitive functioning test indicative of head trauma or concussion. They also answered questions about concussion symptoms. Researchers then fitted them with EEG and EMG equipment and asked them to squeeze a dynamometer and complete a neuropsychological assessment.
One group then proceeded to head a soccer ball thrown from 13 meters 20 times, while the second group performed the same task in virtual reality. Participants executed a defensive header without jumping. Afterward, they retook the King-Devick test and answered questions about concussion symptoms.
Results showed that 90% of participants practicing real soccer heading experienced concussion symptoms, compared to only 10% in the VR group. Head accelerations were greater in the real ball group.
On the King-Devick test, the real ball group showed no change in reaction speed but made more errors. The VR group displayed faster reactions and fewer errors after practice.
Both groups demonstrated more precise force contractions post-training. However, the VR group showed elevated overall brain activity, including increased frontal theta and global alpha and beta activity during the contraction task. The real ball group exhibited elevated corticomuscular coherence, indicating improved connectivity between brain and muscle activity.
“Our findings indicate a short bout of soccer heading may impair cognitive function and disrupt the organization of efficient neural processes that typically accompany motor skill proficiency. Soccer heading also induced corticomuscular hyperconnectivity, which could represent compensatory brain-muscle communication and an inefficient allocation of increased task-related neuromuscular resources,” the study authors concluded.
This study highlights the effects of ball strikes to the head in soccer heading on cognitive functioning. However, the authors noted that the head impacts in this study were generally weaker than those experienced by elite soccer players. The duration of the observed changes remains unknown.
The paper, “Soccer heading immediately alters brain function and brain-muscle communication,” was authored by Johnny V. V. Parr, Liis Uiga, Ben Marshall, and Greg Wood.