running the water numbers

Byron Powell's ultramarathon how-to book is currently on my reading shelf. Unfortunately it's usually buried under a pile of science papers so I don't pick it up as often as I'd like but that's a trail I don't want to run down right now. From what I have read it appears there is useful information for beginner and veteran runners. Get your own copy at iRunFar.

After my Sinister7 dnf I've decided I need to add a bit more rigor to my racing and training. I particularly want to develop a fueling strategy for Lost Souls. Up to this point I've tried to eat and drink frequently without any definition of what that means.

Following Bryon's section on fluid loss I did a little test of how much water I need to consume every hour to prevent dehydration. I went for a 25.3 km run at a 5:46/km pace (so says my gps watch). The entire trip took 2:26. It was calm, blue skies and 24 deg Celsius. A nice summer day. I lost 8 pounds in sweat! I know I sweat more than the average fella and, given my lack of hot weather running, I expected to be pretty sweaty but that's 4 litres of water. According to Bryon's figures I need to consume 1.65 litres of water per hour to remain hydrated. I don't think that's physically possible. I can feel the sloshing in my stomach as I type.

I obviously don't run that fast on longer outings, which will lower my fluid needs. I will hopefully acclimate to the heat over the next 6 weeks, which should further reduce my sweatiness. I also need to repeat this test a couple of times to confirm that number (and hope its not that high again). Whatever the final number what is clear is that I need to consume way more fluids than I have been.