Gordon Burns famously hosted this mental and physical challenge which would involve logic tests and assault courses to find the toughest and brightest contestants.
The logic puzzles would usually involve some kind of rearranging oddly shaped pieces to form a pyramid or something and would be completed against the clock.
The final challenge would be where all the competitors had to complete and army assault course as fast as they could regardless of their size or physical ability. I think women got a head start but fat people didn't. Except fat women of course.