For soccer players, heading a ball is an important part of the game. But players who use this technique a lot might be more likely to suffer short-term balance problems, new research has found. Those repeated head impacts could also cause subtle, previously unknown neurological problems.

While more study is needed to assess the long-term effects of heading a ball, University of Delaware scientists reached this conclusion: The repetitive head impacts may be associated with memory and thinking problems as well as changes to the brain’s white matter.

The researchers evaluated the habits of recreational and club soccer players. The average player was 22 years old and reported heading the ball 451 times in the preceding year. Using electrodes to create a sensation of imbalance, the players walked on a foam pad with their eyes closed. The same test was repeated without the stimulation.

Those who reported the most repetitive head impacts were more likely to be affected by the artificial stimulation, the researchers found. That suggests balance problems are associated with the repeated head impacts from soccer. Players’ hip movement foot placement also changed with every 500 soccer headers.

The effects are subtle, and researchers still don’t know what, if any, long-term complications might result from the repeated head impacts of soccer. Next, the researchers hope to better understand how sensory information is used to maintain balance after head impacts.

Not every player shows the effects of repeated soccer headers. But knowing more about who is most susceptible and designing ways to avoid or rehabilitate balance issues will be the focus of future research.