How to run in the heat: Tips and gear

When it's hot, it's crucial to adapt your running and equipment to continue training. In the heat, the body works even harder. It not only has to supply muscles but also regulate internal temperature. Heart rate increases faster, water loss is greater, and with it, the risk of dehydration increases. So how can you adapt to run safely in hot weather without sessions becoming too difficult? Here are some tips and habits to adopt for successful sessions when the thermometer keeps rising.

Heat: a major physiological constraint

Running, like any prolonged physical effort, will increase energy consumption not only for the mechanical work required for movement but especially to regulate body temperature during exercise. In hot weather and during physical exercise, the body adapts in three complementary ways: increased heart rate, sweating so that sweat evaporates – the main mechanism for body cooling, and dilation of subcutaneous blood vessels to dissipate heat. These adaptation mechanisms compete with the muscle activation necessary for running. Hydration becomes essential to avoid a drop in aerobic performance. Cooling can be accelerated by applying cool towels to key areas, such as the head and neck, or by regularly wetting them.

Ultra-light & breathable clothing

Ultra-lightness and breathability are the key words when choosing running attire in hot weather. Ultra-light and hydrophobic clothing will allow perspiration to pass through. Ultra-lightness is key to prevent sweat accumulation and avoid making the garment heavy. An ultra-light T-shirt or tank top also provides a great feeling of comfort. The ideal is to forget you are wearing clothes. Some technical T-shirts also offer UPF50+ sun protection for optimal protection on sunny summer days – like the Free Runner range which combines ultra-lightness, great breathability, softness, and maximum sun protection.

Early morning or late evening runs

It's crucial to avoid the hottest hours of the day – between 12 PM and 5 PM – and instead favor cooler hours, especially very early in the morning. Running can be practiced up to about 25°C (without too much humidity). Beyond this temperature level, and especially with high humidity, it is not recommended to run outdoors. The humidity in the air limits sweat evaporation, making body cooling more difficult. If you cannot go out at dawn or early in the morning, you should look for shaded routes, preferably in the countryside rather than in the city, and avoid direct sun exposure as much as possible. If you have no other choice but to run in full sun, at least make sure to protect your head well with a cap and wear sunglasses.

An adapted (reduced) pace

In high heat, it's not the time to break records. On the contrary, you need to consider reducing your pace and adapting to the heat. Your heart rate will rise faster than usual because your body has to lower its core temperature in addition to exerting itself for running. Running at your usual target pace will require more effort due to the heat. The successful summer runner is the one who accepts slowing down to better adapt.

Regular hydration

In high heat, insufficient hydration is a guarantee that your outing will become increasingly difficult. Maintaining fluid balance is a priority. There's no question of waiting until you're thirsty. You need to drink very regularly every 15 or 20 minutes and add electrolytes if you tend to sweat a lot.

In conclusion, the essential thing for running in hot weather is to adapt and especially to avoid the following mistakes: running in full sun (for too long) and in the middle of the day, maintaining the same pace as in cool weather, not hydrating regularly (or on the contrary over-hydrating without adding sodium), and not adapting your equipment sufficiently.