World Rugby to use mouthguard data to advise coaches on player availability

There is an increasing body of research to suggest that a high number of head impacts can correlate with neurodegenerative diseases later in life, with or without the presence of concussion or other similar brain injuries.

World Rugby say that the new guidelines will not mandate whether players can play, but will be used to advise coaches and unions about who should play.

The mouthguards, which have been introduced in the men’s and women’s men’s and women’s elite game over the last four years and are worn by about 8,000 players internationally, provide team doctors and medical staff with immediate information about the number of head impacts a player has received, as well as the velocity of the impact.

They have the technology to measure the change in a player’s velocity as well as their rotational force, which are used to determine the severity of the impact. They are worn by most players at the international and elite level and the data is held centrally by World Rugby, which allows the governing body to use the data to better understand head impacts and to update their policies.

Players at this year’s women’s Rugby World Cup are wearing an updated design that also flashes to indicate to the referee when a player has sustained a higher-force impact. If a mouthguard flashes, the player is sent off for a 12-minute head-injury assessment (HIA) and will take a series of tests to see if they are displaying any concussion symptoms.

World Rugby will use the data from all mouthguards to create guidelines for each position, similar to the player training load guidelines that are already in place.

“We see mouthguards playing most value in the long-term,” said Dr Lindsay Starling, the science and medical manager at World Rugby.

“Most of the current research is from NFL and football, which says there is a link between repeated head impacts and long-term brain health consequences, like developing into neurodegenerative diseases like dementia. The mouthguards measure every head impact that occurs so we can quantify how many times they hit their head in a match, training session, and across the season. For long-term data, we can look at the number of concussions over a career, but these mouthguards allow us to quantify the head impacts too.

“What we do know, based on common sense, is that a high number isn’t good. By quantifying collisions, we can help reduce the number. That’s a huge part of it. We can set the range in each position, by month. We will develop the thresholds so players can be flagged as having had a percentage more head impacts in a week than what we accept as average. Then we suggest they reduce the player's load for the next week.”

As the data develops, the criteria for an HIA is getting better. “From all the data over four years, we have a threshold for what is a very big impact,” Dr Starling says. “We look at the 99th percentile, or the biggest 1% of head impacts. Should a player receive a head impact above that, we now have the ability to pick that up, and we think the doctors should see that.”

The intervention comes at a critical time for rugby union. There are now 784 former rugby union players who have joined a lawsuit against World Rugby, England Rugby and the Welsh Rugby Union, who argue that the sport’s governing bodies failed to take reasonable action to prevent serious brain injuries. Many of the players have been diagnosed with early onset dementia and probable chronic traumatic encephalopathy, a condition that can only be diagnosed posthumously.

Comment: Dr Lindsay Starling, science and medical manager at World Rugby on concussion safeguards

Concussions are just one part of the puzzle when it comes to head injuries. While they are so important to understand, what research from football and NFL shows us is that the number of head impacts sustained over a career may have a correlation to developing neurodegenerative diseases like dementia later on in life, even in the absence of concussion.

That’s why it’s so important that we understand how many head impacts a player has sustained. And that was actually a hard thing to measure, until we had smart mouthguards. Introduced about four years ago, the mouthguards are now worn by all elite men’s and women’s 15s and 7s players and keep a track of the number and magnitude of head impacts players experience in matches and training. For long-term data, we have only been able to say how many concussions a player has had over their career, but now we can also see how many head impacts they have had which will prove hugely valuable in both the long and short term.

We want to get to a place where the data we capture can be used to help manage how many head acceleration exposures a player experiences within a week, a month, and across a season, with the aim of reducing unnecessary exposure that could affect their long-term brain health. Right now, we are in the phase of interpreting the information being captured and working with teams to build their understanding of what the numbers mean.

As this knowledge develops, we will be able to establish thresholds of exposure over different timeframes, accompanied by clear recommendations and guidance on how players should be managed. At World Rugby, this means developing benchmarks that allow us to flag when a player has exceeded what we consider a typical number of head impacts in a given period. While we do not yet know exactly what those thresholds are, and they will differ by position and other factors, the ultimate goal is to use this information to guide teams in reducing player load when necessary.

These developments are really important. The mouthguards give us data that means we can follow current players until they retire and then follow them into retirement and see what the impact of their number of head impacts is. But we can’t afford to wait for 50 years, or however long it would be, to get that data. Instead we want to act now. We know that a high number of head impacts is not good, so it’s now about working out what the threshold is where we can say a player has received too many head impacts. The brain is not like a muscle: it doesn’t benefit or strengthen from repeated impacts. Even if we don’t have the data or research to back up that repeated head impacts in rugby lead to worse brain health, we can act with good faith to take measures to protect our players.

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