Soccer players who frequently head the ball may be more likely to experience short-term balance problems, suggesting that repetitive head impacts could potentially lead to subtle neurological deficits not previously recognized, according to a new study by researchers at the University of Delaware (UD).
Further research is needed to study the long-term effects of these repetitive head impacts and to develop any potential interventions.
“Soccer headers are repetitive subconcussive head impacts that may be associated with problems with thinking and memory skills and structural changes in the white matter of the brain,” said study author John Jeka, Ph.D., a professor and chair of the Department of Kinesiology and Applied Physiology in the College of Health Sciences. “But the effect of headers on balance control has not been studied.”
For the study, the researchers observed recreational and club soccer players from the UD community, Wilmington and Newark. Participants reported the number of times they headed the ball and how often they played and practiced. The average player was 22 years old and reported heading the ball 451 times in the past year.
Participants were asked to walk with eyes closed on a foam pad. They were tested under two conditions: one with electrodes placed behind their ears to make them feel like they were falling sideways and another without the stimulation. The electrodes make use of tool called galvanic vestibular stimulation that stimulates the nerves in the inner ear and brain that influence balance.
The findings reveal that players exposed to more repetitive head impacts were more affected by the vestibular stimulation while walking, suggesting subtle balance problems. For every 500 headers that a player reported, their foot placement and hip adduction responses slightly increased, Caccese said.
“At this point, it appears that frequent soccer heading may result in subtle balance impairments,” said Jaclyn B. Caccese, Ph.D., one of the authors of the study. “The question is, how do we get these really subtle effects and how do they manifest to later life complications?”
Because the balance problems are so subtle, there may be no external way to identify the effects of repetitive head impacts, say the researchers.
“We are looking to understand the relationship between head impacts and concussion,” said Fernando V. Santos, a doctoral student in the biomechanics and movement science interdisciplinary program. “These athletes, they’ve experienced head impact and they don’t show any signs.”
The team says that more research is needed to better understand the effects of repetitive head impacts. The next step is to study how people use sensory information to maintain balance following concussions or even mild head impacts that do not result in acute symptoms of concussion.
“The hope is if you can identify concussion and treat it, but also if there are effects from repetitive head impacts, identify individuals who are going to be susceptible to those. Not everyone has effects from repetitive soccer headings,” Caccese said. “We need to identify individuals who do have it, identify why they have it and how to treat it — and if balance deficits persist, then you can design targeted interventions to rehabilitate those balance deficits.”
The research was presented at the American Academy of Neurology’s Sports Concussion Conference in Indianapolis, Ind.
Source: University of Delaware