13 Tips For Avoiding Heat Exhaustion While Running

how to avoid heat illness while runningLast month after finishing the 1/2 Way to Christmas Half Marathon in Dayton, Ohio, I passed out and was taken by ambulance to the ER for very serious dehydration. This was my 28th Half Marathon. I am an experienced runner, certified running coach, and had run this particular race twice before.

This year I ran nearly 40 minutes slower than usual due to the heat. I wore my hydration pack that I don’t normally like to wear, took ice packs at two aid stations to stay cool, and even walked during the race. I thought I was being careful because I wasn’t pushing myself too hard.

I had TailWind in my Camelbak and put ice in my bra. I finished in 2:29 and right in front of a friend of mine who was pacing the 2:30 Half.

As the pacer, he had pushed himself to stay on pace, and once he finished he was struggling to stand. I stayed with him at the finish line tent as he received emergency medical attention and watched as he was slipping out of consciousness and could barely mumble his own name. Eventually, he was taken to the hospital by ambulance.

Following this, I realized I was not okay myself. I quickly told a medic my name, apologized and told her “I am going to pass out.” She immediately sat me down and put ice on me. The last thing I remember telling her was “I can’t see you.”

I am unclear exactly how long I was out of it. The medics did not confirm whether I ever fully lost consciousness or for how long. I just remember repeating myself and saying “I can’t see, I think I am going to pass out.”

Eventually after being cooled down with ice, my vision returned and I started to feel better. I sat with the two paramedics in the truck and had something to drink. My vitals were great and the paramedic said I am obviously a runner because my heart rate and oxygen rates were fantastic.

Initially they weren’t planning to take me to the hospital but then I started cramping, and realized I must be dehydrated. I ended up taking an ambulance to the ER for an IV too. 🚑

My Top Tips For Avoiding Heat Exhaustion As A Runner

1. Wear Road ID. I own a Road ID bracelet (similar to this one on Amazon), but I did not have it on me. It has my name, birthday, and emergency contact information on it which could be useful to have in an emergency.

2. Take a picture of your insurance card. In an emergency you are more likely to have your phone on you, unless you carry your insurance card while you run. This is also useful for non-running emergencies.

3. In extreme heat take off your shirt. I am not always comfortable running in a sports bra, but I should have immediately removed my completely sweat soaked shirt that was only trapping in heat.

4. Drink water and electrolyte drinks slowly. The medics told me to sip my drinks and replenish slowly. Guzzling sports drink at the finish is more dangerous and can do more harm than good.

5. Take care of myself first before I can take care of anyone else. I was with my friend who was in much worse shape, but I was so concerned about him I forgot to take the best care of myself. I should’ve gotten myself inside, out if sweaty clothes, started re-hydrating, and taken off the camelbak (Amazon link) as soon as I was done with it. This was a Christmas themed race, but I never made it inside for the post-race breakfast with Santa.

6. Hydrate before racing. I typically run four days a week and try to stay well hydrated every day not just on race days. Given the heat index I should have pre-hydrated a little more.

7. In emergency heat situations put ice under your armpits. I was putting ice in my bra too while I was walking. When I passed out the medics put bags of ice under my armpits and in my lap.

8. Get help quickly. I was fortunate I was in a good place to get the help I needed quickly, and I spoke up right away. This type of heat exhaustion comes on quickly, often with little warning.

9. Sweat testing. I am working with another PaceBuilders coach, Jill Mongene, to go through sweat testing. She will calculate my personal sweat and sodium levels. This is useful for knowing my own rehydration needs. (For more information about PaceBuilders click here. We include sweat tests for our 1:1 coaching clients)

10. Stay home. The race course was shortened to 2 loops and runners were given the option to only run 1 loop if they felt unsafe completing a 1/2 marathon in a heat index over 100. I should have only run 1 loop, or better yet not run at all! As runners it is hard to skip a race, but jeopardizing our health isn’t worth it. I had no idea just how bad I was feeling until I had to tell the medic I couldn’t see her! That was nearly 20 minutes after I finished running.

11. Leg cramps are a sign of dehydration. My legs started cramping and bulging like never before. They were not just sore from running a half marathon, but extremely painful.

12. Rehydrate with Body Armor or other natural sports drink. I also like to drink TailWind (Amazon link) or coconut water for rehydration. My doctor told me to drink 64 ounces of Body Armor (Amazon link) for the electrolytes.

13. Stay inside during a heat advisory. I ran this race 40 minutes slower than usual which meant I was out in the heat that much longer, and way longer than was safe. I have run marathons in 85 degrees. It was most likely the heat index over 100 and humidity that were the difference here, and simply being outside too long.


I share all of this in case it helps anyone else. Heat illness is serious! It can kill you. Please be careful. I am grateful to be ok and be reminded to take care of myself.

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Cari Masek is a RRCA certified running coach and part of the RunBuzz, PaceBuilders® coaching team.

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