Today I lost 4 pounds in one hour!
It was 79°F and 85% humidity this morning. So I decided it would be a good day to measure my sweat rate.
I weighed myself before I headed out for my run, and then when I got back an hour later.
I lost exactly 4 pounds, or 1.8 kg.
Since I didn't drink anything or pee during my run, that is roughly 1.8 liters of sweat. Or around a ½ gallon.
Yes, this is gross, but it is also good to know.
If I had tried to run a marathon today, I would need to drink about 2 gallons of water to keep up with sweat loss. How many little cups of water at the aid stations is that?
Figure about 4 oz per cup, thats about 64 cups. Wow.
Probably the hottest marathon I ever ran was Chicago 2008 which got to 80° by the end (not as bad as 2007).
I think I drank 2 cups every mile, which is 42 cups. I guess that was a good strategy, because I was fine at the end.
I think I will try this at different temperatures. I would be good to know how much to drink given a particular pace/temperature.
How in the Eff did you get my before pictures? Cripes.
ReplyDeleteIncredible observation. Now I realize how much stress I have been putting on my body through running in this hot NC weather. I know I come back drenched but I never did the weight test. I will really have to focus more on hyrdration, even on my shorter runs.
ReplyDeleteI think Matt Fitzgerald wrote about this, i think he said the body is kind of designed to handle a lose of water when running and trying to replace all the amount you lose through sweating would result in stomach problems.
ReplyDeleteOne advantage of loss of liquid in the body is a lower body weight which helps against the negative effects of performance drop through dehydration.
I think he recommended drinking small amounts often in hot weather.
ARr hear it is the article by Matt;
ReplyDeletehttp://running.competitor.com/2010/05/features/running-101-hydration-during-running_7800
Interesting. You must have been really thirsty by the end of the run!
ReplyDeleteOff subject, but I have a pet peeve: I can't stand when educated adults say "pee." They sound like Kindergarten students. ;-)
yeah. I can't stand educated adults either.
ReplyDeleteRick, I have to disagree with Matt Fitzgerald.
ReplyDeletedrinking to thirst wont work for most people running long.
i'll have to do a whole post on this....
I agree ac. I think If your are thirsty you are already behind the 8 ball with hydration. Not that you can't recoup. But I think drinking earlier is better (not that I necessarily follow my own advice). I have read ultra-marathoners recommend sloshing in the stomach as the barometer of proper hydration. Obviously there is some variation on what works for each person.
ReplyDeleteIf you do a whole post on this, do not forget to mention the salt. As an experienced marathoner I knew to hydrate early and often in hot weather but was surprised by my Chicago Marathon experience.... and after that I am shocked to hear people experienced in running still debating if salt intake is necessary. Salt should be standard at every aid station in every marathon.
ReplyDelete