Week 35 Wrapup

It was really hot this week. Overall, the temperatures are slightly lower because the monsoon season is in full swing. But, the arrival of the monsoons brings the terrible humidity. So, my sweat, it does nothing.

On Wednesday's tempo run I had to stop a couple of times to cool down. I maintained the pace while I was running, but stopped and walked 2 or 3 times because I just felt too hot and sick (This was at 10:30 PM or so, too). Saturday for the long run I was supposed to do 18 miles, but at 17.5 I just said "screw it" (out loud, to no one in particular) and walked the remaining half mile.

I'm learning quite a lot during these long runs, especially about hydration, and how much water actually passes through my body. For reference, I usually drink a half liter before I leave, drink a little over 2 liters out of my camelbak during the run, then maybe a liter when I get back to the car. Afterwards, I'm still down a few pounds, so I obviously sweat and exhale more than that.

For this week's run, I was on a trail with a lot of drinking fountains, so I wasn't trying to ration the camelbak. I figured I'd just drink as much as I need, and use drinking fountains when it's empty. What I discovered is that the rate at which I lose water is higher than I can comfortably replace it (in this heat at least). I tried to drink as much as I could to go through the camelbak as fast as I could, but drinking too much while you're running like that makes your stomach not feel great. So, I just barely finished the camelbak before I finished the run. I felt like I needed and wanted more to drink, but just couldn't do it without risking puking.

So, this tells me that there's got to be some point in this kind of heat where the distance of the long run gets so long that even with an unlimited supply of hydration, I would still drop dead of dehydration on the route because my stomach wouldn't take water in fast enough to replenish what I've lost over the time spent running. I don't know how long that distance is. Maybe it's 50 miles. Maybe it's 26.2. Maybe it's next week's 20 miles. Either way, it's enlightening to discover that even with unlimited leg strength and unlimited water, my maximum running distance is limited by how well my stomach handles being full.

I could probably figure it out mathematically. Take my weight loss during the run, add the weight of fluid consumed. Divide by time, and I get a loss of around 3.7 pounds of fluid per hour. Let's convert to kg since 1 liter is usually 1 kg and call it about 1 3/4 liters of fluid lost per hour. I drank 2 liters of the camelbak in 3 hours (2/3 liter per hour) and felt kind of sick, but let's say I could push it up to 3/4 liter per hour. That's still a net loss of 1 liter per hour. Human body averages 60% water by weight, so I might be around 53 kilograms of water. So, if I lost a liter per hour, I would be completely dessicated after 53 hours. However, I'd die a lot sooner because of blood volume. I read that for every 1% of body weight lost in dehydration, 2.5% of blood volume is lost. If that held true throughout the entire loss, then at 1kg per hour, it would take me about 35 hours to be completely fresh out of blood. It's likely that I would be dead much sooner, however. My quick googling says that 9-12% loss in body weight through dehydration is fatal. If all that's true, that would give me about 8 hours of running in this heat before I die, although I would likely see some pretty severe symptoms before then.

I had previously thought that my concern would be getting enough water, so I had started looking for places on the trail to stash bottles for when my camelbak gets empty. Now that I know that I can't really drink more than what I have, I've got to explore other options. I believe there are three things I can do: 1. I can get in better overall shape so that my body sweats less in the exertion and therefore loses less fluid. 2. I can train my stomach to handle being more full when I run. Or 3., I can hook up a second bag of glucose/saline through an IV. Or, of course, there's always option 4, wait until it's not so blasted hot.

If I'm still running a lot by next summer, I'm hoping that I'm in better shape so that the heat and the sweating wouldn't be such an issue. Otherwise, I'll definitely do what everyone else here does and just switch to shorter milder more infrequent runs in the summer just to maintain until you can really start training again in the fall.