Mouthguards are usually used as protective kits in sports such as rugby and boxing, but in soccer a similar custom-made device is being used to collect data on the frequency and intensity of impacts a player receives to their head.

English soccer expanded its study into the risks of heading the ball on Tuesday with the instrumented PROTECHT mouthguard, developed by Sports & Wellbeing Analytics (SWA), being worn by players in training until the end of the season.

Twelve clubs across the Premier League, English Football League (EFL) and FA Women's Super League (WSL) are participating in the extended study, which follows last season's initial research project with Liverpool and Manchester City.