The Women’s Rugby World Cup has had record attendances and record viewing figures in the United Kingdom, introducing new fans to rugby union.
But what might not be so widely known is that an equipment innovation has also been introduced during the 16-team tournament in England, which is now at the semi-final stage.
Set to be rolled out across the sport at all elite levels after the World Cup concludes next weekend, mouthguards that have a visible LED that flashes red when a player sustains a significant head impact during a match are being worn by players at the World Cup.
Previously used smart mouthguards, which were introduced to the sport in October 2023, had no flashing light and instead informed matchday doctors of strong head collisions via Bluetooth.
World Rugby, rugby union’s world governing body, is hoping the introduction of the LED feature can help raise awareness around head injuries and concussions.
Speaking at the England World Cup player welfare briefing, Lindsay Starling, the science and medical manager for World Rugby, said: “It now means that everyone will be able to tell when a player has sustained a significant head injury during the match because their mouthguard will be flashing red. It will create awareness in the stands and among fans on TV.
“It also means there’s absolutely no delay in a player being pulled off the field after sustaining a big head impact because everyone on the field will see they have had a big knock.” This has happened during this World Cup, with six alert events over one weekend of the group stages.
But how do they work, and will these mouthguards help reduce the severity of head injuries in rugby union, and potentially even be used in other contact sports?
Who makes them?
The clear mouthguards are created by Prevent Biometrics, an American company that has worked with World Rugby since 2021 and provided the first iteration of smart mouthguards that were introduced in 2023.
Its chief science officer, Adam Bartsch, told The Athletic that the mouthguards created for World Rugby have always had LED lights. It is just that the governing body have now decided to turn them on.
Bartsch said: “I suspect on their end, they had to go through some verifications to ensure the data we are providing them was useful and accurate.
“That takes a little bit of time, so it’s no surprise to me that back in 2021, they didn’t tell us to flip on the lights. So it’s taken a few years, but I think that’s kind of the right amount of time for everything to marinate, to get ready for being used on the big stage.”
World Rugby trialled the mouthguards in Major League Rugby, a professional league in America, and the World Rugby Under-20 Championship last month.
Bartsch described the LED mouthguards, which have a rough value of $200-$250 per unit, as “the overnight success that took 20 years”.
The mouthguards have a visible LED light that flashes when a significant head injury has occurred (Prevent Biometrics/World Rugby)
Bartsch, who joined Prevent Biometrics in 2017, started working on the concept of smart LED mouthguards 20 years ago, along with some neurosurgeons and a NASA-trained mathematician. Bartsch said the lights were first turned on in January by the U.S. military, who used them when paratroopers were jumping through a field at night.
“A reader might go: ‘Hey, what’s so hard about sticking a light on a circuit and then sticking that in a mouthguard?’, and I agree it’s not very hard to do,” Bartsch explained. “But to be able to do that and have that smart mouthguard perform to the expectation of that specification, it’s night and day.”
When does the light flash?
The specification Bartsch refers to is the threshold set by World Rugby for a head collision.
The sensors in the mouthguard can decipher how far someone’s head has moved up or down — this is known as a linear movement — and rotated. The light flashes during occurrences over 75 gravities (the measurement for linear movement) and 4,500 radians (the measurement for angular acceleration, telling us how fast the head has rotated) for men, and 65 gravities and 4,500 radians for women.
Bartsch said: “This is the first global specification for this product and I believe it’s going to have long-lasting effects (on protecting players).”
The mouthguard that is changing rugby forever 🙌
The LED smart mouthguard represents world leading innovation and utilises sophisticated technology in real-time for significant improvements for player welfare 💯 pic.twitter.com/NuCC87ogvx
— World Rugby (@WorldRugby) August 14, 2025
Will they help with concussions?
Concussions are the most common type of traumatic brain injury, leading to a temporary disruption in the brain’s ability to function. They can have long-lasting and life-threatening effects, with repeated head trauma connected to an increased risk of chronic traumatic encephalopathy (CTE), a degenerative brain disease that can only be diagnosed after death. Clinical symptoms can include memory loss, confusion and anxiety.
In several contact sports, a number of former players have suffered from neurological issues as a result of head trauma sustained during their playing careers.
In 2015, the NFL agreed to roughly a $1billion-plus (£770million) concussion settlement, with dozens of Black retired players becoming eligible for payouts in 2022 when the league agreed to end race-based testing.
In an ongoing lawsuit, UK sports law solicitors Rylands Garth is representing hundreds of former players from both rugby union and league.
Sam Peters is a former rugby journalist and wrote Concussed: Sport’s Uncomfortable Truth.
Discussing the potential benefits of LED mouthguards, he told The Athletic: “I think the key piece to this is that the medical staff are going to get a real-time read of when the big hits occur.
“What was happening previously was that because these are essentially reliant on Bluetooth technology, which is quite limited in terms of its range, the medical staff were getting deluged with loads of high readings, but they didn’t have any idea when the impact had occurred. Sometimes they were getting a read, which was like 10-15 minutes after the actual event had happened.”
Peters explained how the thresholds for gravities and radians weren’t perfect.
“There isn’t one number where a player will either be concussed or not concussed,” he said. “A lot of the time, it’s kind of repetitive, low-grade impacts, which then accumulate over the course of a match or a few days, which then cause the actual concussive event.
“I think there’s a real risk that they (team doctors) could become reliant and say: ‘Well, they haven’t had a flashing LED; the mouthguards haven’t flashed, so therefore they don’t have a concussion’.”
Luke Griggs, chief executive of UK charity Headway, concurred, saying in a statement to The Athletic that the challenge is to ensure that players, coaches and medical teams are not solely relying on the data to make welfare decisions.
“There are perhaps more obvious potential benefits for the community game, where there are no medics on hand to look out for the more subtle signs of concussion,” he said. “If this technology is reliable and affordable, it could significantly help the process of identifying players who should be removed from the field of play.”
In November 2021, World Rugby launched a global brain health education campaign “to educate and support current and former elite players who might be concerned about their wellbeing and brain health”.
World Rugby’s Starling said: “One of the most important points we can make and just keep drilling home about the mouthguards is that they are head impact devices. The purpose of the mouthguard is to measure head acceleration events. It’s not to identify or diagnose concussions… because there are still concussions that occur at smaller magnitude head impacts.”
Can they be used in other sports?
“Here in the States, all the medical leaders have been stuck in a kind of vicious cycle of products claiming to be able to measure head impacts and be able to send an alert when a serious head impact occurs,” Bartsch said.
“These leaders have been frustrated for decades by the lack of technology that could do the job, and so many of them, I think, have just switched off into saying: ‘Well, it’s hopeless. It’ll never happen’.
“So internationally, Europe will lead the way for both women and men, and then here in the States, it started with the United States military, who have a keen desire to keep their folks healthy and mission-ready, and then, at some point, we’ll see folks like the NFL or the NHL over here in North America learn from what’s been done overseas.”
This mouthguard took 20 years to see the light, but it is unlikely to be the last advancement in monitoring concussions, Bartsch said.
“We’re iterating new versions of hardware, software, and firmware literally every week, so the pace (of innovation) is definitely accelerating.”
Peters said: “AI helps in terms of something called vestibular ocular movement: essentially, how your eyes track. So you remember the old-fashioned finger in front of the eyes? There are really much more sophisticated ways of doing that using mobile phone technology. Cameras on phones can get a much more accurate read of any potential damage when compared against the baseline, so that’s moving forward.
“Cognitive tests have had a radical evolution because there are some big advances in technology. Medical science is moving on all the time, and the technology that’s used to diagnose concussions is getting better and better, helping athletes recover post-concussion, so there are lots of reasons to be optimistic.
“But I always come back to this idea that the only guaranteed way to reduce exposure to brain trauma is to limit contact and limit training, and put stricter limits on the amount of games played.”
Griggs warned, however, that technology alone could not solve the problem. “There needs to be continued focus on changing cultural attitudes to concussion and long-term brain health in rugby to ensure players are not ignoring clear signs of concussion — whether clear and obvious, more subtle, or identified by technology — ore returning to play or training before they are ready to do so,” he said.
(Top photo: Stu Forster/Getty Images)
