Running in the Heat - How to Train When It’s Hot?

The thermometer is well above 30°C and you’re just heading out for a workout? Respect! Keep in mind that running in the heat is a completely different story than, for example, a jog on a cool morning. For this kind of activity to bring benefits and, above all, be safe for you, you need to remember a few basic rules. As it happens, we’ve covered everything important in this article.

How should you approach running on hot days (including choosing the right time, pace, outfit, etc.) so you don’t do yourself any harm? Welcome to another SMMASH guide!

What happens to your body when running in high temperatures?

When you run, your muscles produce a lot of heat, which your body then has to somehow “release” (mainly through the evaporation of sweat from the skin). Under normal conditions, this is a standard process that uses only a small amount of energy. In hot weather, however, cooling becomes much more demanding. That’s why sometimes much more energy goes NOT into the run itself, but into cooling your body down.

For most of us, the barrier of so-called thermal comfort is around 25°C. When the surroundings are warmer, your heart beats faster, your heart rate rises at the same pace, and fatigue hits you sooner.

Which is more dangerous: humidity or temperature?

Interestingly, in practice, humidity may actually be the factor that limits your performance. When it is high (for example 60% or more), sweat evaporation drops drastically, which means the body cannot cool itself effectively.

Is running in hot weather harmful? If so, for whom?

For a healthy person (and we stress: healthy!), running in the heat is not dangerous “in itself.” BUT! You need to know that it can become dangerous if you approach it carelessly (for example, if you don’t prepare properly or ignore the signals your body is sending). In that case, you may run into problems such as:

heat stroke,
dehydration,
sunburn,
drops in blood pressure,
fainting,
heart rhythm disturbances.

You need to be especially careful (and ideally consult a doctor first) if you have any cardiovascular condition, are overweight, or are a beginner runner.

What benefits can training in these conditions offer?

So it doesn’t seem like we devoted the whole article only to risks: summer running, while certainly demanding, can pay off. The human body is capable of adapting even to very difficult conditions. And if you train in them regularly, you’ll notice the effects during activity in “normal,” cooler circumstances too.

Personally, we see the benefits of running in the heat in 3 key areas. They are:

Lower heart rate at the same level of effort.
Increased aerobic capacity (VO2max).
Improved mental toughness (training in difficult conditions strengthens your mindset).

How should you run on hot days?

Before we move on to specific tips, remember that here too, just like in any other sport, common sense is the foundation.

#1 Choose “safe” times and places for activity

If you’re not specifically aiming for heavy sun exposure (for example, you’re not training for an extremely difficult ultramarathon or preparing for a race that will take place on a hot day*), try to train early in the morning (ideally before 9:00 a.m.) or late in the evening (ideally after 8:00 p.m.).

Not only time matters, but also location. If you have the option, choose a forest and shade instead of open spaces and concrete. Forest terrain heats up less than asphalt, and in older forests it can be noticeably cooler.

* In that case, deliberately training in the heat for adaptation purposes is absolutely advisable.

#2 Dress appropriately for the weather

Go for lightweight, breathable technical clothing, preferably in light colors that reflect the sun’s rays. In our online store, you’ll find breathable running shirts and lightweight tank tops that do exactly what you expect from a summer outfit. On top of that, add short leggings, a cap with a visor, UV-protection sunglasses, and sunscreen for exposed skin. Complete your set with breathable running shoes and good socks.

What should you avoid? Above all, cotton, which absorbs sweat, becomes heavy and wet, and instead of helping, only gets in the way.

#3 Adjust your running pace to the weather conditions

Heat is not the best time for chasing personal records. To run relatively comfortably and safely, simply slow down and monitor your heart rate regularly. For many people, this is a period when, instead of long runs of several or even dozens of kilometers, they choose shorter runs of just a few kilometers. Importantly, don’t compare your results to those you achieve on cool days.

#4 Hydrate before, during, and after your run

About 1–2 hours before your planned activity, drink 300–500 ml of water (or possibly an isotonic drink). Also, take an adequate supply of fluids with you for the run itself. If you’re planning a short run (for example, 3–5 kilometers) that will take you “up to an hour,” around 250–500 ml will be enough. If you want to run longer, bring a liter or more. During exercise, replenish fluids with small sips, roughly every few to several minutes or every 1–2 kilometers. After training, reach for hydration as well to replace what your body lost through sweat.

If you follow all of the tips above, we’re convinced that running in the heat can turn out to be enjoyable, safe, and genuinely beneficial for your progress. And remember: if the heat is unbearable, you can always choose treadmill running in an air-conditioned facility.

Getting ready for summer miles? With us, you can dress for the temperature.

Now that you have a clear plan, there’s just one last thing left: getting the right outfit. For that, visit our online store, where breathable running shirts, lightweight tank tops, as well as shorts are waiting for you.