Referees know every decision will be scrutinised. Fans, pundits and players will pour over their calls, creating never-ending debates. It is why they are prepared. Many of the Professional Referee Group, the top officials in the country, have met in Loughborough this week. They meet every few weeks to work and train together, with the officials spread across the country. Lunch is a choice of chicken, teriyaki beef or tofu with vegetables and salad, with protein bars and rice cakes alongside the fruit, granola and Greek yogurts. It is a reminder of the environment. Since becoming professional in 2001 top flight officials have had to adapt. "I never thought referees did as much as what we do now," says Sam Allison, who played for Chippenham Town and Frome Town during his playing career, which started at Swindon. "We are training full-time, sometimes two, three sessions a day, making sure that we are ready on a Saturday afternoon."Allison, a former firefighter, is the fourth official for Manchester City's trip to Crystal Palace on Friday while colleague Sam Barrott has been given Saturday's early match between Liverpool and Nottingham Forest. Barrott took charge of Arsenal's Community Shield win over Manchester City this month and was in the Faroe Islands on 20 August to referee Ki Klaksvik's 0-0 draw with Riga in the Europa Conference League. Different teams and different tactics means a different approach to each game, with officials prepping with Pro Ref's analysis team who provide key information to understand the way a team is going to play, to support the flow of the game. It comes after a summer of work to ensure the officials can match - and better - the demands of the Premier League. "At the moment we've got five substitutions and we see all the time fresh legs for teams can change the momentum in a game," said Barrott. "If three new attacking players are on that are all very pacey after 70 minutes you know they're going to change the way they play, they're going to try and push."That normally means an increase in output for us and when that happens, there's not a point in us where we go, we can't handle this."

We've been trying to push the demands of where we are, everybody's trying to get better. Football has the 1% gains, every game or every training session we're very similar in the mindset, we want to be better."Francis Bunce has been with Pro Ref - rebranded from the Professional Game Match Officials Limited - for 10 years and is now the physical performance manager. He was with the group in Spain last month for their pre-season training camp, putting them through what is viewed as the infamous Maximal Aerobic Speed (MAS) test - an all out six-minute run. "When you look at refereeing in the Premier League and Championship people very rarely talk about their physical qualities or physical capabilities," he tells BBC Sport."They've all done so well to keep developing and they look like athletes on the pitch - they are athletes."We're in a very different space with match officials, they are naturally some years older than the players and you can't get away from that because having a 21-year-old referee would be very difficult in the Premier League with everything you need to learn and experience.