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Chaski Coach Zandy Mangold is an elite ultra runner and a coach for runners of all ages, abilities, and experience levels. He has competed in several of the hottest, driest and most humid ultramarathons on the planet including victories at the Keys 100 and the seven day Atacama Crossing. Aside from being a coach and elite competitor, he is also a photographer and has documented races in the most extreme climates in places such as Antarctica, Madagascar, Nepal, Namibia, and the Sahara, Gobi and Atacama deserts. So let's just say he knows a thing or two about heat training.

Why should you heat train?

Summer is back with a vengeance, and if you are one of the approximately 20 million people racing this summer, you will have to contend with high temperatures during your race. In other words, summer running love is like a heat wave.

Summer running success is not about beating the heat, but rather embracing your hot-blooded mammalian nature and adapting your body to the warm climate while managing your effort and fueling smartly.

What Happens When You Run in the Heat?

First the bad news. Along with high altitude, headwinds, and elevation gain, heat completes the grand slam of naturally occurring performance limiting  factors.

Even if the outside temperature remains constant, our bodies continue to heat up as we run, and the longer we run the hotter we get. The hotter we get the more difficult it is to exercise at a hard effort as our body works overtime to maintain homeostasis, i.e. a functional core temperature.

Human bodies regulate core temperature in two ways - sweating and moving blood flow to the skin, but blood flow to the epidermis diverts oxygen from muscles, thus decreasing muscular efficiency. Reduced blood flow to the gut doesn’t directly hinder performance, although it can impede digestion and cause nausea, factors which ultimately lead to slower times or even a dreaded DNF.

The good news - and there is a lot - is that our bodies have evolved to adapt quickly to hot conditions. Training in the heat and / or adhering to heat training protocols will increase blood plasma volume and hemoglobin mass in as little as 7-14 days with regular exposure. (*Recent research shows that women may require longer exposure than men.)

Greater blood plasma volume allows more fluid to be sweated away before leading to dehydration and there is more blood to flow to the extremities without sacrificing blood flow to the muscles and gut. Furthermore, greater hemoglobin mass enhances the oxygen carrying capacity of red blood cells, legally mimicking the effect of the performance enhancing drug EPO. It wasn’t a burrito your honor - it was my hot baths!

How Do I Heat Train?

Fortunately, for summer runners, heat training is surprisingly uncomplicated as our bodies do most of the work for us. The following are four easy ways to train hot!

#1 Acclimatize by running in the heat

Research indicates that running in the heat at low effort for 7-10 days will ensure significant adaptations. The longer you exercise in the heat, the more you’ll reach the full potential for acclimatization, but you have to proceed with caution initially in order to not place too much stress on your body.

Wearing a breathable hat, arm sleeves and generous amount of sunscreen will allow for more time in the sun. Also, hydrate with an electrolyte mixture before, during (if over an hour) and after workouts. Prior to his record setting Western States run in 2019 Jim Walmsley not only trained at high altitude, but also at high heat, dropping down to Phoenix and other low-altitude (and thus much hotter) areas for scorching hot training runs leading up to the race.

#2 Layer up

For example, if the weather is not quite hot enough, you can run with extra layers of clothes which will raise your core temperature while exercising and force your body to react and adapt as though you are running in a hot climate.

While training for the hottest ultramarathon in the world, the Badwater 135, Pete Kostelnick who lived in Ohio at the time would dress for a ski expedition, but go for an easy run instead, starting about a month prior to the race. His mad method seemed to work as he set the Badwater 135 record in 2016.

#3 Get in the tub!

If the above methods sound too miserable, you could opt for a passive acclimation strategy which requires nothing more than a hot bath of 15 -30 minutes post workout. Research indicates that merely six consecutive sessions will lower core temperature, decrease time to sweat and increase blood plasma volume. A 2015 study showed that women require about twice the amount of heat acclimation as men.

#4 Run on a treadmill with no fan or AC

When we run outside there is automatically airflow which helps sweat evaporate from our skin and thus cool our core temperature. In contrast, if you run on a treadmill with no airflow to whisk away sweat, your body has to work much harder to stay cool and as result, you will benefit from some adaptations. Extra credit for hotboxing your treadmill.

*If you aspire to be your crew’s runnerd, you can explain that acclimatization refers to environmental exposure to heat, i.e. running in hot weather or living in a hot climate, while acclimation refers to controlled exposure to heat such as saunas, hot baths and wearing extra clothes.

Embrace The Hot Race

While hot temperatures don’t lend themselves to record breaking times, you can still run hard, not bonk and outperform the competition with the right preparation and race execution. Drinking a fluid with electrolytes before the race, wearing a hat, sunscreen and applying cool water to your shirt and face when possible, can all help regulate your body temperature during a race.

Summer training should be embraced, not avoided, and when fall races and cool temperatures arrive you can take advantage of the hard earned heat adaptations and run faster than ever.  

— Zandy Mangold