Running in the heat - how to train when it's hot?

The thermometer is well above 30 degrees Celsius and you're just heading out for a workout? Respect! Remember that running in the heat is a completely different story from a jog on a cool morning. For this kind of activity to bring benefits and, above all, be safe for you, you need to keep a few basic rules in mind. 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 get rid of, mainly through the evaporation of sweat from the skin. While in normal conditions this is a standard process that only uses a small amount of energy, in hot weather cooling becomes much more demanding. That is 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 degrees Celsius. When the environment is 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 can actually be the factor that limits your performance. When it is high (for example 60% or more), sweat evaporation drops dramatically, which means the body is unable to 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 risky if you approach it carelessly, for example if you do not prepare or ignore the signals your body is sending you. In that case, you may end up with problems such as:

heatstroke,
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 does training in these conditions offer?

So that this article is not only about the risks, running in summer, while certainly demanding, can pay off. The human body can adapt even to very difficult conditions. And if you train in them regularly, you will notice the effects during activity in “normal” and cooler circumstances as well.

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

Lower heart rate at the same effort level.
An increase in VO2max.
Improved mental toughness (training in difficult conditions strengthens your mindset).

How should you run on hot days?

Before we move on to detailed instructions, remember that, as in any other sport, common sense is the foundation here too.

#1 Choose “safe” times and places for activity

If you do not particularly care about high sun exposure (for example, you are not training for an extremely tough 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) or late in the evening (ideally after 20:00).

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

* In that case, training deliberately in warm conditions for adaptation purposes is absolutely recommended.

#2 Dress appropriately for the weather

Go for light and breathable technical clothing, ideally in bright colours that reflect the sun's rays. In our online store you will 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-filter sunglasses, and sunscreen on exposed skin. Complete your kit with breathable running shoes and good socks.

What should you avoid? Above all, cotton, which soaks up 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 ideal for breaking personal bests. To run in relative comfort and stay safe, simply slow down and monitor your heart rate regularly. For many people, this is the period when instead of long runs of a dozen or several dozen kilometres, they choose shorter runs of a few kilometres. Importantly, do not compare your results with what you achieve on cool days.

#4 Hydrate before, during and after your run

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

If you follow all the tips above, we are convinced that running in the heat will turn out to be enjoyable, safe and genuinely beneficial for your development. 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'll dress for the temperature.

Now that you have a clear plan, the last thing left is to get the right outfit. For that, visit our online store, where you'll find breathable running shirts, lightweight tank tops, as well as shorts.