Liverpool's players have returned to pre-season training - and that means the dreaded lactate test.
With the full squad back in action this week, the players were filmed taking part in the pre-season exercise that has typically been dominated by James Milner, who left the club on a free transfer this summer.
The 37-year-old, who ended his eight-year stay at Anfield earlier this summer as he departed the club to join Brighton and Hove Albion on a free transfer, had reigned as the Reds' fitness drills, and specifically the lactate acid test, champion in all of his eight pre-seasons with the club.
Manager Jurgen Klopp anointed Mohamed Salah as the winner of this year's competition, followed by new signing Dominik Szoboszlai.
Here is all you need to know about the gruelling drill that humbles some of the Reds' superstars.
READ MORE: Dominik Szoboszlai shares six-word message after first day of Liverpool training
What is the lactate acid test?
The infamous fitness drill, which is overseen by the Reds' fitness guru Andreas Kornmayer, sees players complete numerous laps around the perimeter of the pitches at the AXA Training Centre before having their blood samples measured. According to EKF Diagnostics, training to improve a player's lactate threshold is one of the most effective "performance markers" used by football teams.
The point of the drill is to measure the maximum intensity at which a player can compete before suffering from high levels of lactate in the blood, which causes fatigue.
The detailed report by EFK explains how regular testing of lactate levels in the blood can enhance a player's threshold within a training programme and therefore improve their endurance levels ahead of the upcoming season.
What have players said about the lactate acid test?
Andy Robertson's first memories as the life of a Liverpool player are scarred by his experience of the lactate acid test in the summer of 2017 shortly after he signed from Hull City.
Speaking in an interview with Open Goal in 2018, the left-back detailed how the gruelling examination caused him to be sick on the first day of his Liverpool career as he struggled to keep pace.
“It’s horrible, running round the pitch, I’m doing it with Danny Ings and that,” said Robertson of his first experience of a Liverpool pre-season. “My medical went on for two days – it was quite a long medical – so I wasn’t eating, I wasn’t doing this and that. I was fit, because I had three weeks at Hull and I was looking after myself.
“So I’m taking the lactate test and I’m thinking, ‘my stomach’s a bit dodgy here’. I started gagging and I was sick everywhere.
“Halfway around I had to stop and be sick, then I tried to catch them up because I’m thinking, ‘I can’t drop out at this point’, because this point was like you are super unfit, that was the point you had to get by.
“So I was sick around the pitch, then I had to stop because they have to take the blood out your ear, and I was sick when I was getting my blood taken.
“I went another lap and I was like ‘I need to stop’.”
