Several months ago I read an article about determining your exercise sweat rate to determine how much water you lose during a particular activity. Today I decided to find out what my sweat rate was for moderate cycling. So I weighed myself (scale goes to tenths) before getting on the bike w/ trainer, rode moderately hard for an hour and then weighed myself afterward. I lost 2.6 lbs in that one hour. Now, most of that will be water which is released when the fuel is burned and some of it will be for cooling me off (a neat trick we humans have).
Since water on earth (where I live) weighs about 8.3 lbs per gallon, that means I used almost a third of a gallon of water in about one hour. Wow. Since my bike water bottles are about 20 ounces each and a gallon has 128 fluid ounces in it, that means that to stay even with my sweat rate I need to drink a full two bottles of water every hour. That explains why I go through so much. It doesn’t explain why I seem to need so much more than the other riders around me. I’ll do a 60 mile ride and go through all 6 of my water bottles *at least* once and sometimes more, and I’m not needing to urinate it out. In fact, many times I end up feeling dehydrated after that. But people that I will ride with will only consume one or two bottles of water for that same distance.
I don’t understand why I go through so much more. Perhaps it’s because of my weight, because I respond to heat differently, because I am working harder than them for the same speed (heavier body and bike). I’ll have to do this test again when I’ve lost 20-30 pounds or so and see if the sweat rate is any different.
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