So the TARC 100 is now 11 days away. This past Saturday, with my very first 100-miler rapidly approaching, I figured I should collect some data as I tried to get my logistics in order. One of the aspects of running that we as endurance runners can control to some degree is our hydration level. Hydration is one of the factors that can determine whether you can actually even finish a race. Dehydration can lead to a breakdown in your ability to run and in extreme cases shut you down completely. What many of us often forget is that over-hydration can have just as devastating of an effect on our bodies and our ability to continue as dehydration. So how does one determine how much water and electrolytes to take in?
Well, you have to have data, and one of the easiest ways to determine how much water you are losing while running is to take a sweat test. Before going out for a 60 to 90 minutes run, you strip down to nothing and weigh yourself. Then while on your run you do not take in anything – no hydration, no food, nothing. Upon returning home or to the gym, you once again strip down to nothing and hop on the scale. Subtracting your post-run weight from your pre-run weight tells you just how much water you have lost with each pound representing approximately 16 ounces of water. You then divide the number of ounces by the minutes you ran and then multiply by 60 and that is your hourly sweat rate in ounces per hour.
And that is what I did – I ran 7 miles in 59.7 minutes outdoors in the heat.
My pre-run weight was 176.8 pounds.
My post-run weight was 172.6 pounds.
I did the math. I checked it twice.
And then I panicked.
Just under 68 ounces of water per hour.
Granted I was running about 3 1/2 minutes per mile faster than I plan to at the TARC 100; granted it was 91° outside; but 68 ounces per hour??? That’s over a 1/2 gallon of water I am sweating out! That was nearly 2.4% of my body weight in an hour. Race officials don’t like that.
Now obviously I will not be running the TARC 100 without hydration, however, from what I understand, it is difficult for our bodies to comfortably consume more than about 28 ounces of liquid per hour. That leaves me with a 40 ounce hourly deficit. Multiply that by the 24 hours I hope to complete the race in and you get a 960 ounce deficit, better known as 60 pounds.
60 POUNDS???
Obviously I can’t lose 60 pounds in a race, but the numbers do have me concerned when it comes to my ability to replace what is lost over the course of 100 miles.
If any of my ultra-running friends (Steve? Maddy? Goji? Jeremy D? et al) have any words of advice or wisdom, I would greatly appreciate them right about now, because I am sitting here sweating…sweating because I’m in a panic about sweating too much!
Run Luau Run 
Not that this is my thing, and more because I don’t want to get outta bed and head to my skyscraper… I looked it up. This seemed mildly helpful. I liked the drink lots in the days and hours leading up.
http://stason.org/TULARC/sports/running/59-I-sweat-more-than-I-can-replace-during-a-long-run-ride.html#.UayUhCd5mc0
But I was thinking there must be some clothing that reduces sweating ( or is that just skin)? And what about anything else to help with cooling to fool your sweaty body? 😉 Ice cubes at pit stops? Cooling… I don’t know… Lotion?
Good luck!! This is big, Luau (the run, not your sweating). You got this.
Very interesting.
It looks like you need to drink 12 gallons of fluid over 24 hours to maintain equilibrium. This comes out to 2 quarts per hour which doesn’t seem that difficult to consume.
While it may be difficult for your body to consume more than 28 ounces per hour, you are participating in an endurence event that will push your body beyond normal.
With all of that liquid I would be very careful about electrolytes so theydo not get depleted. That means gatorade and such.
I used to run a 7.5 mile course and was always amused that I would loose 5lbs on that run. Seemed impossible, but it happened to everyone else aso.
Good luck!