GymBox calls Flatline, its new Farringdon class, “the hardest in the world”. It requires a cardiologist on site, and those who risk it must sign a waiver beforehand. We spoke to fitness maniac Tom Wheatley, AKA The Allrounder, after he’d finished it. “It was like every muscle wanted to stop working,” Tom wailed. “I didn’t have a clue how I was going to carry on. After, I was covered in sweat and could barely hold myself upright. I laid on the floor for about five minutes.” Neato! If you want to get involved, GymBox Farringdon opens today.