In 2024, World Rugby made using instrumented mouth guards mandatory for elite-level competition. And for good reason.

A recent review of studies measuring concussion incidence between 2014 and 2025 in the Rugby Union concludes that 9.74 concussions occur per 1,000 player hours. And repetitive head injury has been shown to lead to eventual cognitive complications.

Basically, more serious bonks on the head means players are more likely to suffer later in life.

But do these mouth guards work?

They do, but a new study from University of Otago – Ōtākou Whakaihu Waka in New Zealand reveals they don’t work effectively for everyone.

“The problem is that almost every commercial system uses a one-size-fits-all approach, assuming every player has the same head as a 50th-percentile adult male, whether they’re a 10-year-old girl or a 130kg premier men’s player,” says Melanie Bussey of Otago’s School of Physical Education Sport and Exercise Sciences.

CAPTION: Rugby scrum IMAGE: Shutterstock

She calls for the sports-tech industry and researchers to account for people of different sex, age and size when designing and collating statistics on the impact of such preventative wearables.

When testing a more inclusive head model for females, the injury risk score changed by nearly 54 percent. Other testing models were adapted for weight and showed significant differences. These results also impact on the indicators of whether individuals were high-risk, which is a highly notable preventative measure.

Bussey, lead author on the paper, says this is a simple fix.

“If we want smart mouth guards to improve safety across the whole game, then the modeling behind them needs to be inclusive. Accurate monitoring is not just about better technology. It is about making sure that technology works for everyone.”

More like this: Putting the pressure on injury prevention