The Big Brother housemates have begun tackling the assault course in preparation for tonight's task.
They have been given protective clothing to wear for the task by Big Brother.
Les Dennis was first to have go, running around as fast as he could. He seemed puffed out after his exertions.
Sue was next to try crawling along the rope above the hot tub.
There's a twist to the challenge - the two winners with the fastest times are allowed to send a message home.
The two losers will have something played to the house that they have said about a fellow housemate.
Melinda hasn't been taking part in the practice because she is feeling unwell.