The Smart Mouthguard: How a Gumshield Became Sport's Most Important Sensor
- Shane Riddle
- Jun 20
- 7 min read
Updated: Jul 5
For decades the mouthguard also known as a gumshield did one job, protect teeth. Today, in the elite game, the same piece of kit has quietly become one of the most important sensors in sport. A sensor that can flash red the instant a player takes a dangerous knock and send a doctor running. This is one of the clearest examples of innovation reshaping player welfare, and the governing bodies leading it, from World Rugby to the NFL are publishing the data to prove it works. In this article we'll explore how the smart mouthguard works, what it already does today, and what it might do next.
Key Takeaways:
A sensor where it matters most: Instrumented mouthguards sit against the teeth, the part of the body most rigidly connected to the skull, making them an unusually accurate place to measure how the head moves on impact.
Real-time alerts, not just data: In elite rugby, a mouthguard that detects a high-acceleration event flashes and pings the medical team, triggering an immediate off-field assessment.
Two different jobs: Rugby uses the device to remove players in-game right now; the NFL mainly uses mouthguard sensors to gather research that reshapes rules and equipment.
The numbers are real: World Rugby reported around 90% mouthguard uptake at a recent World Cup, generating more than 20,000 measured head acceleration events across the tournament.
The science is honest about limits: A head acceleration event is not the same as a concussion, the technology flags risk, and a doctor still makes the call.
The next frontier is the grassroots game: The big ambition is to bring affordable versions to community and youth sport, though that remains a work in progress.
Table of Contents
Smart Mouthguard Quick Facts:
An instrumented mouthguard contains a tiny accelerometer and gyroscope that measure both the linear and rotational movement of the head on impact.
In elite rugby, an alert is triggered at roughly 75g for men and 65g for women in linear acceleration, plus 4,500 radians per second squared of rotation for both.
World Rugby integrated smart-mouthguard alerts into its Head Injury Assessment from January 2024, after debuting them in the women's WXV competition in October 2023.
At a recent World Cup, around 90% of players wore one, recording 20,000+ head acceleration events.
The NFL has run a mouthguard-sensor program since 2019, now spanning professional clubs and several universities.
Sources: World Rugby, BBC Sport, NFL Health & Safety, Adelaide University
What Is a Smart Mouthguard?
An instrumented mouthguard, often shortened to iMG, looks almost identical to an ordinary gumshield. The difference is inside in which a miniature accelerometer and gyroscope that track how the head accelerates and rotates when a player is hit. World Rugby calls the thing being measured a head acceleration event (HAE): the change in speed or velocity of the head caused either by a direct blow or by the head being whipped around after a hit to the body.
Why the mouth?
Because it is the best seat in the house, the teeth are rigidly coupled to the skull, so a sensor held against them moves almost exactly as the brain's bony housing does. Far more faithfully than a sensor in a helmet or a headband, which can slip and rattle. As NFL chief medical officer Dr Allen Sills put it, the league wanted to get "inside the helmet and closer to the target of interest" and the mouthguard sits closest to the brain.
It is worth being precise here, because the difference matters, the device measures force and motion, not concussion. A big number is a flag for risk, not a diagnosis. That distinction shapes everything about how the technology is used.
How Rugby Uses It Today
This is where the technology has gone furthest, and it ships today. In elite rugby, when a player's mouthguard records an impact above the set threshold, it does two things at once, an LED on the device flashes and an alert pings the medical team's app. At the Women's Rugby World Cup 2025 (22 August–27 September), referees were instructed to stop play on sight of a flashing mouthguard so the player could be assessed, rather than waiting for a pitchside doctor to spot a problem and find a gap in play.
The thresholds are specific and, importantly, sex-specific, an alert triggers at around 75g for men and 65g for women in linear acceleration, with a shared rotational trigger of 4,500 radians per second squared. The lower female threshold reflects emerging evidence that women may experience a similar rate of concussion despite fewer high-acceleration impacts.
Once an alert fires, the player gets an immediate on-field check, and if the doctor has any concern they leave the field for a full Head Injury Assessment. The reason this matters is captured by a striking figure from World Rugby's chief medical officer, Professor Éanna Falvey: around 15% of the concussions rugby used to catch only showed up after the game or days later where events that slipped through at the time because the player had no obvious symptoms. The mouthguard is designed to catch exactly those silent hits. World Rugby reported that at a recent World Cup, around 90% of players wore one, generating more than 20,000 head acceleration events across the tournament.
"Now everybody will be able to tell when a player has sustained a significant head impact during the match such that it has triggered an alert." — Professor Éanna Falvey, World Rugby Chief Medical Officer
How American Football Uses It Differently
The NFL has been collecting mouthguard data even longer, its sensor programme launched in 2019 but it uses the device for a noticeably different purpose. Working with Align Technology (the company behind Invisalign), the league makes custom-fit sensor mouthguards using intraoral scanners, and the sensors capture kinematic data including impact speed, direction, force, location and severity. The programme spans professional clubs and a group of partner universities.
Crucially, in American football this is primarily a research tool, not an in-game removal trigger. The data feeds back into rule changes, equipment design and training techniques. That feedback loop appears to be paying off, with the NFL recording 182 concussions in the 2024 season, a 17% drop on 2023 and the fewest in a decade. One mouthguard-sensor study run with the Children's Hospital of Philadelphia followed 98 players across four seasons and found that facemasks which have barely changed in design were taking a surprising share of the impact, pointing to a new avenue for safer equipment.
What the Research Actually Shows
The genuine value of all this is in peer-reviewed work, and the findings are concrete. Studies using instrumented mouthguards in elite rugby have shown that tackles where the ball-carrier is hit above the sternum carry a greater propensity to produce high-magnitude head acceleration events, the evidence that directly supports lowering legal tackle height to protect players and help understand how much impact is too much. In youth American football, a study using mouthguard sensors found that tackle-football players experienced roughly 15 times more head impacts than flag-football players, and 23 times more hard impacts which is useful and sobering context for any parent weighing up the options.
Closer to home, Australian rules football is asking the same question of its youngest players and an Australian company is at the centre of it. The AFL began trialing instrumented mouthguards made by Melbourne-based HitIQ back in 2019, and that same technology is now being pointed at the junior game. In South Australia, a joint trial run by SAHMRI and the University of Adelaide has fitted HitIQ smart mouthguards to players at Norwood Football Club's SANFL and SANFLW sides, pairing each impact reading with brain MRI and cognitive testing. The team has since won a Channel 7 Children's Research Foundation grant to extend the work to junior athletes aged 14 to 16, with the explicit aim of establishing concussion thresholds tuned to a still-developing brain. That distinction is the whole point as rugby researchers have also found, young players can show concussion well below the levels set for adults, so a force that looks safe for a grown professional may not be safe for a fourteen-year-old.
This is the honest promise of the technology, not a magic concussion detector, but a way to see, count and study impacts that were previously invisible — and then change the rules of the game accordingly.
Final Thoughts
The mouthguard's quiet promotion from tooth-protector to brain-protector is one of the most genuinely hopeful stories in sport's relationship with technology. It does not remove the risk of contact sport, and it does not replace a doctor's judgement and the people building it are refreshingly clear about both points. But it gives players, parents and medics something they never had before, an objective real-time window into what the head is actually experiencing.
As the technology gets cheaper and spreads beyond the elite game, the most important matches it influences may be the ones played on a muddy Saturday-morning field, far from any television camera. If you're fascinated by how innovation is changing the rules of play, explore our guide to the future of sports technology next.
Frequently Asked Questions
Q: Does a smart mouthguard diagnose concussion?
A: No. It measures how hard and how fast the head moves on impact and flags events above a set threshold. A flag indicates risk, after which a trained doctor performs the actual assessment and makes the diagnosis.
Q: What is a "head acceleration event"?
A: It's the change in the head's speed or rotation caused by a hit, either a direct blow to the head or the head being jolted after a hit to the body. World Rugby uses the measurement to decide when a player should be checked.
Q: Why are the alert thresholds different for men and women?
A: Evidence suggests women may suffer concussion at a similar rate to men despite experiencing fewer high-acceleration impacts, so World Rugby set a lower female trigger (around 65g versus 75g) to account for that difference.
Q: Can I buy a smart mouthguard for my child's team?
A: Versions exist commercially, but cost has been a barrier to widespread grassroots use. Bringing an affordable, community-grade device to youth and amateur sport is a stated goal rather than a finished reality, so check current availability and pricing before relying on one.
Q: Are smart mouthguards used in other sports?
A: Rugby league and other contact sports have run instrumented-mouthguard studies, and the underlying sensor technology is sport-agnostic. Rugby union and American football are simply the furthest along in putting it to practical use.
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