Karting is hardcore - I can only imagine what a 70 lap F1 race must be like. Horrific i think.

Lewis Hamilton was recently described by the McLaren trainer as being "as fit or fitter than any Olympian" - and the McLaren trainer used to be an Olympic trainer.

You can blame Senna for that, he raised the game in terms of fitness.

Aside from the physical exertion required to pilot an F1 car (never mid survive a race) the fitter you are, the longer you'll be able to perform at your mental peak. Therefore, the fitter you are, the better competition driver you will be.