Researchers investigating the risk to the brain from heading a football commonly focus on velocity and force. Specifically, the quicker a ball travels, the harder it reportedly bounces back. These assumptions have fueled years of debate concerning which footballs are deemed the safest.
A study conducted in England uncovered a different kind of event lurking within the same collision—an occurrence registered in the frontal lobe of the brain even before the head has begun to move at all. The findings of this research were published in the journal Proceedings of the Institution of Mechanical Engineers: Journal of Sports Engineering and Technology.
Investigators from Loughborough University’s Sports Technology Institute sought to look beyond typical metrics. The majority of football heading impact studies rely on sensors placed externally on the skull or on crash test dummies. These instruments track how rapidly the head jerks and how the neck absorbs the blow. Often, they fail to account for what is actually happening inside the brain itself.
Lead author Ieuan Phillips and Professor Andy Harland, who has been examining football’s impact on the game for two decades, employed an alternative method. They constructed an artificial head—a skull shell filled with brain-mimicking gel—and inserted a hydrophone into the cavity.
This sensor does not measure movement; instead, it attentively listens for pressure waves within the brain. The device detected a sharp pressure spike propagating through the gel towards the front of the brain with every ball impact. It reached its peak mere microseconds after contact.
On a graph, this manifests as a distinct peak. There is no extraneous noise or slow hum caused by head movement. It is purely a swift wave emanating from the point of impact, recorded at a rate of 10 million readings per second. It was here that the team made an unexpected discovery.
The wave arrives before the head has a chance to start moving—before acceleration begins and before brain strain occurs. This happened faster than any conventional measurement. Prior to this research, nobody had measured the pressure impulse directly inside a model of a football header impact. Accelerometer sensors were not designed to capture this signal.
Separate studies on brain injury have previously linked abrupt internal pressure surges within the skull to phenomena observed when soldiers are exposed to blast waves, which cause damage to cells and blood vessels.
A paper utilizing lab-grown brain organoids established that shockwaves alone can disrupt brain cell activity. The Loughborough study cannot confirm analogous effects, but it did register similar magnitudes of pressure energy reaching the forebrain.
The team gathered 20 footballs representing key models from the past century. These spanned older leather panels stitched with cotton, modern heat-bonded synthetic materials, and variations in between.
The researchers launched each ball at the artificial head at match-realistic speeds, tested both when dry and wet, and under various temperatures. Since heading conditions on a Saturday pitch can vary, the lab replicated those conditions.
Across the 20 balls tested, the amplitude of the pressure wave varied dramatically. The largest differences amounted to a factor of 55—one ball delivered a slight forward impulse, while another delivered a much stronger one at the same velocity.
If certain ball constructions transmit less energy along this specific pathway, then the construction of the ball becomes a lever engineers can utilize. Answering the “why” is more complex. Ball weight, surface firmness, and how much the ball deforms upon impact are all distinct variables.
Earlier work from the same lab determined that leather balls held different moisture-dependent masses compared to synthetic ones. This new study does not pinpoint exactly which singular ball property is responsible for the pressure spike.
The researchers are exercising caution in both their published material and interviews because the methodology employed is a model system. No actual volunteer headed a ball, nor was memory or mood tracked before and after the experiments.
It remains unknown whether this pulse, repeated thousands of times over a career, contributes to the elevated rates of dementia among former professional athletes. This risk is indeed real. A landmark study in Glasgow involving over 7,000 former Scottish professionals showed they were dying from neurodegenerative diseases approximately three and a half times more frequently than a control group.
Harland, having spent 20 years studying the consequences of head impacts in football, stated that this allows the team to provide a much more granular description of how energy is transferred during a header.
“There is still a great deal of work to be done before we fully grasp what this means for brain health,” he remarked. “These findings open avenues for working on ball design and testing specifications that minimize energy transmission into the brain.”
The picture of head impact has now become more detailed. Before this work, the field only possessed two clear indicators—head acceleration and brain strain. Now, a third factor has entered the equation: a measurable pressure wave impacting the front of the brain microseconds before head movement concludes.
A Swedish analysis of top-division player data indicated higher dementia rates among outfield players who headed the ball frequently, with no excess cases found among goalkeepers who rarely did so.
Certifications for footballs may now include a threshold value for this pressure wave, in addition to existing criteria for size and weight. Manufacturers have a target, and leagues have leverage. The first tangible metric in the debate over whether ball design impacts brain health is now available.
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