Soccer players who frequently head the ball may be increasing their risk for concussion, a new study reports.

The study, published Wednesday in Neurology, included 222 amateur soccer players — 175 men and 47 women — who reported the number of times they headed the ball over a two-week period. The athletes also reported any unintentional head impacts, such as collisions with other players or the goal post.

Over the two-week period, men had head contact with the ball an average of 44 times, while women headed the ball an average of 27 times. Overall, players reported heading the ball an average of 5.3 times a game. Players who headed the ball the most (those in the top quartile of heading reports) were three times as likely to have concussion symptoms, such as pain, dizziness and feeling dazed, compared to those players in the lowest quartile.

Collisions with another player or the goal post were far more risky. Those with two or more unintentional head collisions were six times as likely to have concussion symptoms as those who reported a single impact. In 470 reports of head impacts, a fifth resulted in moderate or severe symptoms of concussion.

An accompanying editorial noted that the study focused on adult players, and the results can’t be generalized to teenagers and children. However, they noted that the study group reported three practices and two games in two weeks, a schedule that would be comparable to that of both adults and children playing in amateur leagues.

The lead author, Dr. Michael L. Lipton, a professor of radiology at Albert Einstein College of Medicine and Montefiore Medical Center, said the finding is just the beginning of an effort to understand the long-term implications of heading the ball, and whether all forms of heading carry similar risks. He said the data don’t yet support a ban on the practice.

“We don’t know how much is too much. It would be great to say ‘no heading,’ but we don’t have enough information to say that. Public health interventions have to be based on evidence.”