Isaac Hayden is a 'machine' in training and and 'does not like to show that he is tired', according to Newcastle United goalkeeper Rob Elliot.
The 25-year-old has proved an important player for the Magpies in the last year-and-a-half in particular and has the legs to break up opposition attacks and cover a lot of ground.
While we are accustomed to seeing Hayden do this in games - even filling in at wing-back on occasion this season - the midfielder also trains in a similar way.
In a live Instagram Q&A with former Charlton team-mate Stuart Fleetwood, who is now a personal trainer, Elliot was asked which player was always leading the pack during group running sessions - and his answer was not a huge surprise.
"Probably Isaac - he's just a machine. He's just one of them, like you say, who's designed for it," Elliot said. "He loves a tackle, has got a great mentality, always trains hard and has got that mentality just to keep running.
"He doesn't like to show that he's tired if he is. He's got that brilliant athleticism and you just look and think, 'Flipping hell!'
"Obviously, we've got quite a lot like Jack Colback as well. His is pure determination, hard work. You've got Jonjo, who's just a natural. He just grinds it out.
"The scary thing is, there is not that much in it. Issie, Sean, Matty Longstaff are the ones that really put the real yards in. DeAndre Yedlin is up and down the line but Issie is the one that sticks out for me, especially the position he plays, centre mid, which is probably one of the hardest ones."
