Paul may have been blacking up
Here's a description of the contestant's attempt. Someone's probably working on collecting some images to illustrate it.
Paul does some exercises, including push-ups, punching, and running on the spot. He then tries to use a measuring spoon to collect some sweat from his body, but finds nothing. After exclaiming, “Al Murray’s going to win this, that fat bastard.”, he does some more exercise, including running around outside, and eventually manages to collect 12 drops of grey-coloured sweat. In the studio, it is reveals that the colour of the sweat was due to his moisturiser and the die from his T-shirt. Paul earns first place.
(Written by JoGo and proofread by Karl Craven)