I wrote a feature on the KF yewars ago, and attended the filming of the assualt course section - they film the entire series for this section over a couple of days.
Like most people, I have watched the show and thought 'I could do that ...' - how wrong I was!
The jump-off bit looks like about four feet on TV, is actually the height of a first-floor window, and the last running section is about a 1:4 gradient.
I was invited to have a go, and declined. The sargeant in chage - the course is on an Army PT Instructor training camp - told me that they don't normally allow anyone to go untuil they have had sufficient physical training. A Daily Mirror journalist had tried the day before, and was physically sick when he finished, way behind any of the contestants!
Havn't seen the new series, but have no reason to assume they have made itr any easier!