Please see my longer post on preparing for extreme heat on race day HERE. The note below was originally published in a closed forum for my private clients as the black flags were raised the night before the 2016 Marine Corps Marathon.
I'm sure you've seen the heat advisory notice for tomorrow. Please bear in mind: the high is only expected to hit 80. If you Google "how to hydrate in heat" you are going to get terrific advice for running in the Sahara, where temps regularly exceed 101. It is more effort to cool down than to warm up, so in hot weather higher heart rates will yield slower paces. Those A paces that felt comfortably hard in the EAT may feel damn near impossible on race day. Trying to push pace isn't a good idea, you have to respect your effort levels; 170bpm will still feel like 170bpm even if the pace on your watch doesn't look that bad. Also note that these temps aren't likely to hit until 11am, so the sooner you get to the start line, THE MORE RUNNING YOU CAN DO IN LOWER TEMPS. Now, for hydration. Short version:
Drink up tonight and have an extra Nuun before bed, then another one 2 hours before your race begins (if you plan on having breakfast, drink your Nuun THEN WAIT at least ten minutes to eat. Water is absorbed within 5 minutes on an empty stomach; when combined with food it can take up to 120). During the race itself, more than 4 cups of water per hour isn't a great idea.
Long Version:
1. you are not actually in a desert. You don't need to grab water just because you pass it on the course.
2. when you do take water, remember to take sips. Volunteers just fill the cups as instructed, it's not like anyone put serious thought into how much you need.
3. Each cup will have about 3-4 oz of liquid. There are 13 water stations, and 4x13=52. Your body can absorb 34 oz of liquid per hour....BUT ONLY in the most extreme heat and humidity, and ONLY when it is at rest. Again, we are not actually in a desert, we are running a marathon.
4. Your kidneys are the limiting factor: they can only filter so much water per hour (0.26 gallons or 4 cups to be precise), and most of the energy in your body is being directed to your muscles. Trying to consume more than 4 cups of water per hour is pushing the upper limit of what your body can reasonably be expected to do.
5. Water will sit in your belly while it waits for its turn to be filtered, so if you are consuming more than 4 cups of water per hour, you will be able to feel the water sloshing around like a water balloon. It's a very good way to vomit, which will definitely dehydrate you. Let's not do that.
6. Wine dehydrates. You know who you are. After the bridge, drink up!
It's going to be fine, because you are #coachedandloved #andwinningatlife
Coach MK Fleming is the founder of Fitness Protection, LLC where she coaches all kinds of runners for $30 per month and gives marathon plans away for free. Click here to download her Marathon Selection Guide!