Quote Originally Posted by Mike T View Post
I guess I am lucky in that I sweat very little and have for example run a couple of marathons during which my intake of food/fluid was zero and yet my times were if anything better than those where I had indulged. 1 kg is about 1.5% of the average runners weight = 1.5% reduction in VO2max = 1.5% increase in time; a handicap I can do without. Are others really sure they need it, or are they sticking with the now discredited advice that you need to drink BEFORE you are thirsty.
that not correct at all....VO2 Max has a relationship with bodyweight and the surface area of an person but as anything you carry does not have a oxygen requirement, nor increase your surface area, in a direct sense, it will not act as the equivalent increase in mass.

Furthermre, your capacity to perform any work is massively compromised by a drop in blood plasma caused by dehydration which is going to afffect oxygen transport and many other metabolic activities so your actual vO2 max isn't going to be available for you to use, basically you will slow down far more than you realise though the percieved effort level will probably increase.

Again, whether you accpt this or not doesn't stop it being true