成人快手

3.8 kilometres of swimming, 180 kilometres of cycling and 42.2 kilometres of running, all in the same race - it can only be Ironman.

On the eve of the sport's most extreme World Championships in Hawaii, six-time Ironman champion Mark Allen spoke to Sportshour's Caroline Barker about exactly who would put themselves through one of the toughest races on the planet.

Picture: six-time Ironman champion Mark Allen (credit: Getty)