Catching concussions early in sport

During the Women’s Rugby World Cup this year, you may have noticed something a bit different about the mouthguards the players have been wearing. This year, World Rugby has been trialing some new technology to help catch the incidence of concussions early – mouthguards that are equipped with accelerometers, gyroscopes, a Bluetooth connection, and flashing LED lights.

In contact sports like rugby, American football, hockey, boxing, and wrestling, concussions are a known hazard. Concussions occur when rapid velocity changes caused by impacts to the head, neck, and body cause the brain to move within the skull. This movement can cause injury to the brain which can result in a variety of symptoms including headache, dizziness, nausea, and vision problems. Concussions can also impact thinking, emotions, and the ability to sleep.

The mouthguards being used in the Women’s Rugby World Cup measure the force of impact events the player is subjected to and, if the force meets a certain threshold, will send a Bluetooth alert to support staff. Flashing LED lights provide a visual cue to referees so they can immediately stop play and send the player for a head injury assessment. For women, the threshold for an alert is when a player experiences an impact of 65gs. These high-g very short duration forces (like colliding with another player) are what cause the type of brain movement that results in a concussion. (Note: this is different from what we think of as the g-forces that a fighter pilot might endure, which are lower but sustained for a longer time and cause a different set of issues, such as blood pooling in the legs).

So far, the mouthguards are yielding results, with six impact events picked up over the course of one weekend of matches. Where the mouthguards are particularly valuable are for concussions that might not exhibit symptoms until days after. According to Dr. Éanna Falvey, chief medical officer for World Rugby, continued play after a concussion-causing event raises the risk of prolonged recovery. If a player doesn’t know they are concussed, they may continue playing and make their condition worse.

Repeated concussions or even subconcussive impacts have been linked to a condition called traumatic concussive encephalopathy (CTE), which can appear years after repeated head injuries. Symptoms range from physical issues like dizziness and tremors, to mental health issues such as depression, and can develop into a form of dementia. While CTE shares some similarities with Alzheimer's disease, they are distinct from one another. Currently, professional athletes are the largest group with CTE.

CTE is only able to be diagnosed via autopsy, with the first case confirmed in 2005 in football player “Iron Mike” Webster. Boston University’s CTE Center has since posthumously diagnosed hundreds of former athletes through donor brain examination. While pro athletes are possibly the largest group studied for CTE, other people at risk include those in the military, first responders, and victims of physical violence.

The mouthguards being used currently are just the most recent iteration of the technology, with non-flashing versions being used by World Rugby since 2023, and similar technology used at University of British Columbia for their Thunderbirds hockey team. These high-tech mouthguards are not mandatory for players. Since the medical data they collect and transmit is considered private, the players need to be comfortable with agreeing to use them. But, in the Women’s Rugby World Cup, the uptake has been close to 100%, with only a handful of players willing but unable to wear them due to having dental braces.

This is particularly important as concussions in women are under studied. The incidence of concussions in rugby is higher in women than in men despite an estimated lower impact rate in women’s rugby. Understanding why that may be the case can lead to the development of preventative measures specific to women players. Additionally, susceptibility to concussions can be highly individual, and studying the types of problematic impacts of a particular player could help with individualized interventions. These could include introducing changes in technique, better protective equipment, or even changing the rules of the sport to make it safer (which is what the NFL did with their kick-off rules this year).

As this technology becomes more widely used in professional sports, the hope is that it becomes accessible to youth and amateur sports. According to Boston University, young players may be more likely to develop CTE when they get older because of injuries sustained in their teenage years. Being able to detect concussions quickly, reduce their frequency, and prevent repetitive head injuries across all contact sports will help reduce the number of athletes whose lives are affected by CTE. Also, if aspiring players see their sports heroes treating concussions with the seriousness they deserve, they’ll be more likely to treat them seriously too.

Learn more

Women's Rugby World Cup players trialling flashing mouthguards to help predict concussions 2025. Kate O’Halloran (ABC News) Last accessed 2025/09/30

Flashing mouthgards for concussion to be introduced at Women’s Rugby World Cup 2025. Sean Ingle (The Guardian) Last accessed 2025/09/30

High-tech mouthguard tracks head impacts during varsity hockey playoffs 2022. Lou Bosshart (UBC) Last accessed 2025/09/30

From concussion to breast injuries: How the Women’s Rugby World Cup is sparking a medical revolution 2025. Hannah Bradfield (Women’s Health) Last accessed 2025/09/30

Women's Rugby World Cup: Flashing mouthguards to indicate HIA check 2025. Mike Henson (BBC) Last accessed 2025/09/30

Research on CTE and Concussions Changed the NFL. Experts Say That’s Not Enough 2024. Doug Most (Boston University) Last accessed 2025/09/30

What a lifetime of playing football can do to the human brain 2020. Brian Resnick (WashU McKelvey School of Engineering) Last accessed 2025/09/30

Chronic Traumatic Encephalopathy (Wikipedia) Last accessed 2025/09/30

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Dal study of football players sheds light on how concussions affect the brain 2024. Tehosterihens Deer (CBC) Last accessed 2025/09/30

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Flashing mouthguards that signal a head injury will soon hit the rugby field – are they a game changer? 2025. Nick Draper and Kevin Mangan (The Conversation) Last accessed 2025/09/30

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