Help me diagnose my stomach issues

[u/leecshaver]

Last Friday I did my first ultra, a self-organized 50k. Things were going really well until about mile 25. By that point, I had eaten about 300 grams of carbs, which I knew was not enough, but I was doing good on hydration (still sweating and peeing). About 100 of those grams were from tailwind so I thought I was good on electrolytes too.

Then at mile 23 I met a friend who gave me a bunch of grapes, pita chips, a coke, and some peanut M&Ms. At this point I stopped counting carbs but I was probably still behind where I should have been. We ran together after that point, and I felt really good for the next two miles.

Then, I started feeling nauseous. At this point it was also getting hot (near 90F), and the trail was really exposed. I could run for about 5 minutes, then I'd feel nauseous, and have to walk for a bit. I drank a lot of water over the last 10 miles, about 1.5L. I stopped sweating a couple of times so I knew I was behind on hydration for that last stretch. My friend (an ultra veteran) kept giving me some chewable salt tabs. Other than those, tailwind, and a couple of cliff bloks, I didn't eat anything else for those last 8 to 10 miles.

My thinking is that I should have started on the electrolytes earlier when I knew it was going to get hot, drank a bunch more water when I stopped to meet my friend (other than the coke I didn't drink any fluids), and that hopefully that would have helped with nausea so I could have eaten more solid food over the last stretch of the run. Those last 10 miles were mostly downhill and I felt fine, so I know that if it hadn't been for the stomach issues I could have covered that ground a lot faster.

I know more experience is the only way to know for sure, but curious what others think, or other people's experience.

[u/Just-Context-4703]

Id consume electrolytes from the word go. And, yeah, eating a bunch of random food low on fluids will put your lower intestine in a tough spot and be generally suboptimal on processing food leading to food intolerance, etc etc.

Throw in the high temps and this is just a tough situation to turn around.

[u/leecshaver → u/Just-Context-4703]

Yeah good call on how the low fluids impacts digestion, I hadn't though of that. I think my biggest mistake in all of this was not factoring how the heat later in the run would impact me. I had done all of my training runs, even long runs, before the heat of the day and hadn't thought about this.

[u/skyrunner00]

Here is a potential problem. When you are dehydrated, your sodium concentration in the body actually increases. That is because we lose relatively more water than sodium when we sweat. If you suddenly start taking too much sodium without adequately rehydrating first, you are actually driving your body sodium even higher. That may lead to not being able to sweat, because sweating would lead to even higher sodium level, potentially causing hypernatremia, and nausea is one of the symptoms of that.

Another possible factor is that the body prioritizes cooling over digestion. If you are already dehydrated, it is a tough state to be in because stomach no longer works well, and whatever you eat and drink may just be sitting in your stomach and not absorbing, and just further irritating it. The only solution really is to cool down and rehydrate, then start taking calories.

[u/leecshaver → u/skyrunner00]

Yeah that makes sense. There were a couple of shady spots in those last 10 miles where I'd stop, cool off for a bit, and drink some water. I felt really good for a few minutes after each of those stops.

[u/Federal__Dust]

You diagnosed yourself: you were dehydrated, probably suffering from heat stroke, and then you went full goat mode, eating a bunch of random stuff at unknown intervals and randomly taking salt tabs without additional water.

[u/Temporary-Flight-724]

I’m glad you finished it! Great work! My 2 cents is not to consume anything you didn’t during training. Ignore what others offer you, even if they are ultra veterans. You know your body best.

[u/billskionce]

Your core body temperature was too high. I know that you’re thinking, “well, duh”.

Past a certain point, an elevated core body temperature for a sustained period of time is going to make you feel nauseated.

It may just be too humid. Your body cools itself by sweating, but the sweat only cools you when it evaporates. If it’s too humid, your sweat doesn’t evaporate, and therefore, doesn’t cool you. Your core body temperature may keep going up.

Options are: slowing down, running at a cooler time of day, avoiding directly sunlight when possible, or worse yet, running on a treadmill.

It may not even matter how hydrated you are, unfortunately.