By Kate O’halloran

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This year’s Women’s Rugby World Cup has been hailed as a groundbreaking event for women’s sport, with viewership figures over the first weekend surpassing that of the entire 2022 tournament.

But the competition, held in England, will also be remembered for its revolutionary approach to concussion: a growing issue for a number of sports, highlighted by increasing cases of posthumously diagnosed CTE.

This includes, most recently, the former West Coast Eagle Adam Hunter.

Players from across the 16 participating nations have been trialling what may prove to be the next frontier in its management: LED mouthguards that light up when a player sustains an impact that could lead to a concussion.

Mouthguards predict likelihood of concussion based on hits

The innovative approach has been led by World Rugby’s science and medical manager Dr Lindsay Starling and consultant Dr Eanna Falvey, who has previously worked with the British and Irish Lions.

Dr Falvey explains that the mouthguards do not ‘diagnose’ concussions but are set up to predict when they might occur.

“We know that bigger impacts are more likely to cause a concussion event, so what we’ve done is used the mouthguard to identify those large impacts,” he says.

The mouthguards work using an in-built sensor and ‘threshold’ system. If a player sustains an impact over a certain force, they flash red and send a Bluetooth signal to support staff at the ground, indicating the need for an HIA (head injury assessment).

A prototype of the current model was developed in 2022, which similarly sent a Bluetooth alert, but did not light up.

Two key factors determine the threshold: the speed at which the head moves forward or backward (called peak linear acceleration), and the speed at which the head rotates (peak angular acceleration).

While these provide a best estimate of when someone might sustain a concussion, they are not foolproof.

“What we’ve seen from our data set is that most of the concussion events happen above the threshold, but there are some that sit lower, and that’s what we’re currently evaluating”, Dr Falvey explains.

“We’re not sure if that’s to do with cumulative impacts, fatigue, or something about the players themselves.”

Promisingly, however, the mouthguards are identifying potential concussions that may have been missed otherwise.

Over one weekend of the group stages of the World Cup, he says, there were six alert events, one of which was not picked up by medical staff.

Dr Falvey suggests that in this case, the mouthguard may have picked up one of the approximately 18 per cent of concussions which do not result in symptoms until days after the incident.

And while such a concussion would likely have been diagnosed once a player self-reports symptoms, there is an advantage to picking it up earlier.

“If we don’t know about something, we can’t treat it, but the earlier we see these events, the better.”

Data shows women and men experience concussion differently

One key factor used in current modelling is sex, with the alert threshold set lower for women than men.

Dr Falvey says mouthguard data shows that women and men experience concussion at similar rates, but the way they are concussed differs.

While there may be less ‘intense’ hits in the women’s game, women tend to be concussed at lower intensities, resulting in a comparable overall number of concussions.

Female athletes are also known to report more concussion symptoms than men and experience them for longer periods of time.

They also report more ‘baseline’ symptoms, meaning they report more symptoms indicative of concussion before sustaining one.

Dr Starling argues this is an ‘added’ bonus of their concussion research, because it helps teams better understand women as athletes:

“It’s really helpful, even if those symptoms aren’t related to a concussion incident, because it’s a check-in point for our medical teams to understand what’s going on with our players and sometimes uncover some underlying things that we need to work on,” she said.

Individualised thresholds the way forward

There are also individual differences in the way concussions are experienced, which the team hope will form part of the evolution of the mouthguard.

World Rugby data indicates that the most important factors in sustaining a concussion are your history of concussions, number of symptoms, and a history of ‘slow’ recovery from previous concussions.

While these are currently taken into account when athletes are given a ‘return to play’ timeline, Dr Falvey is keen to see them used to set individualised mouthguard thresholds.

Dr Starling says that while this is the next step for their team, more data is needed.

“To individualise, you need to have a lot of data on a person, so we need players to wear their mouthguards for a [long] period of time to really understand what that player’s picture looks like,” she said.

As Dr Falvey explains, one complicating factor is that some players sustain a larger number of head acceleration events than others, even when they play in the same position and same competition.

“Out of caution we want to look at those particular players’ techniques, to see why they’re getting these larger number of events and what we can do about it,” Dr Falvey said.

“Is it because of poor technique? Because if it is, we can try and correct that.”

Community to benefit from elite mouthguard data

It’s hoped the data being collected at the elite level will benefit participants in community sport.

Dr Falvey points out that while many parents are worried about their children playing rugby, data shows that there are far fewer hits, at a much lower intensity, at the community level.

However, the advantage of using an LED mouthguard in the community setting is that it will light up to alert those in attendance, even if they don’t have officials monitoring for concussions.

It is likely there will be a lower threshold for mouthguards to light up at the community level, a number the World Rugby team are working on.

They are also collecting a range of additional data from the mouthguards, including measures such as duration and power, in collaboration with US company Biocore, who work with the NFL, to monitor their impact on concussions.

In addition to working with several other codes, such as the AFL and NRL in Australia, they have also been approached by an eclectic mix of potential clients, including the FBI, and the American Department of War, who are worried about the head impacts sustained by soldiers using parachutes.

“My attitude on this is that the data is not a competitive thing, this is something we can all share and learn from each other,” Dr Falvey said.

“From our point of view rugby is lucky because we cover over 120 countries, so we have huge scope to look at this, and the data is hugely transferable, not just to contact sports.”