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5 Things You Need to Know About Running in the Heat

Hey, how’s it going everyone? Coach Kyle here!

Today you’re going to learn about how to handle and what to expect with the rising summer temps. Especially for new runners who have started running earlier this spring, they may not know what to expect with their running as the weather warms.

For experienced runners, this is an opportunity to learn something new and possibly improve your training even further.

Your Speeds May Slow

The first thing you need to keep in mind with run training as the outdoor temperatures increase is that your speeds will slow down if you stay within the appropriate levels of perceived exertion for your workouts.

Even in comfortable running temps your core temperature still drastically increases when performing physical activity and becomes a big limiter of performance and this is multiplied when outside air temperatures are already high.

But you must always keep in mind that it’s OK for you to slow in heat and humidity. Never try to maintain speeds for your easy runs, tempo runs, etc in hot weather that you were doing in the early spring when temps were comfortable.

How Much Does Temp Slow Us?

We can plug in various race distances and speeds to get a good idea of how higher degrees slow our speeds.

For example, a 4-hour marathon at a temperature around 50 degrees Fahrenheit is about perfect. But if we add 30 degrees to a fairly uncomfortable 80 degrees Fahrenheit we’re suddenly running 10-20 seconds slower per mile, and I think that’s the best case!

What if we crank up the humidity? 70 degrees and 70% humidity have us running even slower than 80 degrees without humidity.

A very general suggestion would be that you may slow around 4-5 seconds per mile for each 1ºC / ~2ºF as you go over 60 degrees F.

How to Adapt to the Heat

Some good news is that even though your speed may slow and your perceived exertion may increase, you can use heat to your advantage!

First, if you have a race that you’re training for which will take place in the heat, you can use heat during training to improve upon how well you’re likely to perform during that warm event.

Second, if you are training for a race in cooler conditions you can use heat to again, improve how well you are likely to perform in the cooler temps!

The simplest way to acclimatize to heat is to simply train in the heat! This could be as easy as performing your few easy short runs of the week during warmer parts of the day, such as over a lunch break. I may save my easy runs for the afternoon but keep my harder and longer workouts in the morning. 1980 US Olympic Marathon team member, Benjii Durden, used to even do his workouts in the heat, in Atlanta, with extra layers on.

I even recall a study that compared runners in a warm and humid room to runners in the same room with more comfortable conditions, but extra layers of clothing on and the researchers tested rectal temps and concluded that both training in the heat or wearing extra layers can trigger heat adaptations.

Aside from actually training in the heat and/or with an extra layer or two on, other methods may be to simply jump right into a sauna or hot bath after a run while your core temperature is still elevated. I’ve even had clients perform hot yoga as a means of heat training!

I don’t want to go too in-depth when it comes to research on this subject but there is a great deal of variety when it comes to temp and time suggestions. Even just 15-20 minutes in a sauna, hot tub, or a warm bath is likely to produce some positive effect. Some studies go as long as 40 minutes in a hot tub, but I think even half the time is likely to be worthwhile.

What are the Benefits of Heat Training?

Again, without diving too deep into the literature, the key benefit of some heat training is that your body becomes better at thermoregulation, aka cooling yourself.

Primarily, we find that the you that is more heat adapted will become better at sweating, which is our primary means of cooling. You will start to sweat sooner in a run at a lower core temp to try to keep ahead of it, you’ll sweat more, your sweat will contain fewer electrolytes, and you’ll have more pronounced pit sweat stains when nervous.

I know you’re excited about better sweat, but there’s more! Your body’s blood plasma volume will rise and this can improve your heart stroke volume and cardiac output. Skin blood flow can improve and this is a big help when it comes to improving how well you cool yourself.

One of my favorite ways to add in some heat exposure is to do a 10-minute meditation in the hot bathtub after a run!

When Do We Need Heat Training?

A little bit is never going to be a bad thing.

If you’re like me and tend to avoid any big goal races in the hot summer and save them for the fall, the heat training will still improve our performances. Even in cooler temps, we will benefit from enhanced thermoregulation.

For those of you who may not want to regularly either run in the heat or do some sort of hot water immersion post-run, you’re likely ok only doing it for a few weeks before the big event! Multiple studies show that even a couple weeks with regular heat sessions can be enough to prep you for a race. Be aware that the enhancements start to diminish drastically after a week if you don’t keep up with some heat exposure, but if we’re a month out from a race you could likely even benefit from just doing 2-4 easy runs weekly in the heat or adding in hot water immersions after them.

If you like what you just learned and want to get more info on my sometimes unconventional yet proven tactics for helping my runners improve their running through sustainable training habits, nutritional guidance, developing great mindfulness practices, and incorporating easy to do running-specific strength work and having all of it come together with great accountability and motivation, download a guide at where share with you how to implement some different parts of my coaching into your training.