A new study has revealed that heading a soccer ball, even just once, can set off a cascade of biological signals that resemble the early aftermath of a concussion.
Researchers measured blood samples from 302 amateur male players before, immediately after, and 24 to 48 hours after matches, using video footage to quantify the frequency and force of each header.
The biomarkers that signal brain‑cell stress
The analysis detected rises in two proteins — S100B and p‑tau217 — that are widely used as indicators of neuronal injury. The magnitude of the increase corresponded to how often and how hard the players headed the ball.
Although the proteins returned to baseline within a day or two, the investigators caution that the temporary spike does not rule out cumulative damage, especially for athletes who head the ball repeatedly over a season.
A broader context of head‑impact research
The findings echo a 2025 investigation that linked repeated head trauma in soccer and other football codes to neuronal loss and chronic inflammation, prompting soccer governing bodies to trim practice limits for headers despite the lack of a scientifically defined safe threshold.
Experts such as Samantha Bureau, Marsh Königs and Peter Theobald, who contributed to the research, suggest that tracking the same athletes throughout a full season could clarify how these micro‑injuries accumulate and whether they translate into higher rates of neurodegenerative disease later in life.