Warning: Running in the Heat

running in the heat

I’ve participated in two road races where a runner has died on the course. Their tragic and unexpected deaths shocked everyone. Both runners were regulars on the local racing circuit. On both days the temperatures had climbed well past 85º F during the race.

Runners feel a certain degree of invincibility earned through healthy living and regular workouts. But, when another runner dies doing the one thing that connects us all, it reveals our vulnerability. We don’t need to run scared, but we all need to be extra careful when running in the heat.

How Heat Stresses a Runner’s Body

Your head pounds, your legs threaten to cramp, and you feel a pit in your stomach. Your face is as red as the embers of a summer barbecue and your just a bit off-balance. A gritty, salty, film covers the back of your neck and shoulders. You struggle to maintain what is normally a routine pace as you make your way home on another hot summer run.

Sound familiar? Most of us have experienced some degree of heat exhaustion on our runs. It’s a dangerous area that compromises our running performance and possible our well-being.


When temperatures rise, we sweat more. All that sweating shifts the way our blood flows. Blood that is normally flowing to our muscles and our heart is diverted to the surface of the skin to release sweat. Two bad things are happening here. First, we’re becoming dehydrated quickly. And, second, our muscles and vital organs are forced to work under a greater stress load.

Specifically, our hearts are under extreme stress. The heart must move blood around the body to fuel our muscles. When we lose blood volume through profuse sweating and redirection to the skin’s surface, the heart must work faster to meet the demands of the runner. Our heart rate increases and even a normal run feels incredibly difficult.

To make matters worse, the viscosity of the blood changes as we lose plasma. The thicker blood also makes things tougher on our entire vascular system. In these conditions, even a small anomaly or heart condition can become fatal.


Because the blood is being diverted away from the working muscles to other areas of the body, our efficiency is compromised. Muscles fueled by oxygen need to find other energy sources and a long run quickly begins to feel like an interval workout. This leads to cramping and often affects the larger muscle groups first.

[bctt tweet=”Scorching summer heat can destroy your running performance”]

Tips for Running in the Heat

Adjust your running pace to account for changes in temperature. My friends over at Runners Connect have a helpful temperature calculator to help with that. I plugged in a recent run and the times lined up perfectly. I compared a 65º 10K training run at 7:00 pace with the same run on an 85° day. The calculator came up with 7:11 pace. That’s exactly what I ran yesterday in those conditions! I’m impressed.

Start your runs slower than normal and increase your pace if everything feels alright. Run a course that allows you to stop early if you can. I like to run a number of loops so that I can stop at the end of the driveway for a drink every few miles on hot days.

Hydrate well before, during and after your run. Drink plenty of water before your run (not all at once), consider a diluted sports drink on the run to help replace electrolytes quickly, and enjoy a recovery drink after your workout followed by water throughout the day. Avoid drinking too much during hot weather.

Pee test – I know it sounds gross, but here it is: If you hydrate well, your urine should be the color of lemonade. Not perfectly clear, and not darker in color. If you are taking vitamin supplements or medications you may see a bright yellow color, but not too worry. Dark yellow to brown spells trouble.

[bctt tweet=”Some really good hot weather running tips”]

Run early or late. Summer long runs usually start in the 5 o’clock hour. Things heat up quickly after 7am. Night running is also popular with lots of runners, but make sure your safe out there.

Look for shade. Run under the trees to avoid direct exposure to the sun. Concrete and pavement radiate heat, so look for grassy areas or nice trails on hot days.

Stick your shirt in the freezer. It doesn’t last forever, but this pre-cooling technique will help you stay cool a bit longer. Your shirt can be damp when you put it in the freezer, but if it’s wet it’ll be tough to put on when you take it out.

Put ice in your hat. This is a trick I learned from my parents. Put a handful of ice cubes inside your hat to help keep you cool for as long as possible.

Wear sunglasses. Sunglasses not only protect your eyes, but they help keep your face relaxed which improves your overall running form. And, they deflect a lot of flying insects.

Use sunscreen liberally. I probably don’t need to elaborate here. Just be smart.

Have a backup plan. If you’ve ever had a bad training run, you know how valuable it can be to carry a phone or have a backup plan. Always let someone know that you’re out on a run. On hot days, consider carrying your phone for when you need a friend to pick you up. I usually tell my family where I’m running and when to expect me home. If I don’t arrive within 15-20 minutes of my goal time, come pick me up.

Be safe and enjoy the miles this summer! If you have other tricks to beat the heat, please leave them in the Comments section for others to read.


  • http://running.competitor.com/2014/06/training/5-reasons-heat-affects-performance_11671/5
  • http://runnersconnect.net/how-to-run-in-the-heat/
  • http://www.runnersworld.com/the-starting-line/running-heat

4 thoughts on “Warning: Running in the Heat

  1. Perhaps the best post I’ve read this season on running in the heat. I’m going to check out the pace calculator for running in warmer temperatures. It’s not only good for keeping you safe, but for making you feel better about your pace slowing in the hot temperatures.

    1. Thanks, Jackie! I know what you mean. I was feeling a bit deflated about my performance the other day until the plugged the numbers into the calculator. Now, I can set proper expectations for myself. Enjoy the miles!

  2. Great post Jason. As you know, New England transitioned quickly from winter – er spring – to summer like temperatures and they are having a major impact on my training runs. I typically run during the workday (lunch) and my paces have slowed significantly (~20s per mile) and I feel so much worse than I did on similar runs over the past few months (also I have allergy induced asthma so I am dealing with that too). Hoping that my half marathon goes well on Sunday despite my recent training runs!

    1. Hey, Kim. Yeah, the pollen has been awful lately. I’ve been dealing with a scratchy throat on my runs. Not fun. I’ll be thinking good thoughts for you on Sunday.

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