It is now a mandatory requirement that all first team players at Premier League teams are tested, to provide a more accurate timeframe for when they are fit to return to action following a head injury.

In previous years, players would have to complete a Sport Concussion Assessment Tool (SCAT) document - a paper-based test of memory and recall - following a head injury and would only be cleared to play again following satisfactory scores in relation to their normal levels.

However, the CNT tests are designed to test cognitive functions typically experienced by players after a concussion, including speed of processing, attention and memory, and will help the medical team make more robust decisions about fitness to return to play.

Newcastle-based NeuroCog, led by Dr David Millar, carried out the tests over several days at United's Benton training ground.

Dr Paul Catterson, the club's Head of Medical Services, said: "I think the clear benefits are that we're being more scientific with our testing of the players.

"Player welfare is so important and we are ready in case of any head injury during the season - and hopefully we can bring them back to play quicker as well."