Trail running is a demanding outdoor sport. When the heat rises, every stride can become a genuine test. To avoid putting yourself in danger, knowing how to handle these conditions is essential. Here is everything you need to know about trail running in the heat.
What are the dangers of trail running in the heat?
Like hiking in the heat, trail running comes with several risks. The most serious is heatstroke. Also known as severe hyperthermia, it occurs when the body can no longer regulate its temperature. It can lead to organ failure or, in the most severe cases, death .
With intense summer sun, especially in the mountains or on exposed terrain, sunburn is another hazard. It can intensify the feeling of heat and contribute to the onset of heat stroke.
Another extremely common hazard is dehydration. Through exertion and sweating, you can lose several litres of water during a race. If this loss is not replenished, you risk a loss of focus, digestive upset, dizziness or even long-term kidney issues. And it is not just water. A lack of sodium can also take its toll, triggering nausea, headaches and altered consciousness.
Finally, heat directly impairs brain function. During an effort as intense as a trail run, your focus and reflexes can suffer. The risk of falls and resulting injury increases significantly.
Tips for running in extreme heat
Running in intense heat carries risks, but a few precautions can reduce them. First, learn what to wear for a trail run. We recommend technical clothing and avoiding cotton, which retains moisture. Choose lightweight, breathable, quick-drying trail t-shirts and trail shorts. Light colours are also recommended, as they absorb less heat. For lightweight options, the LACHA vest (60 g in size S) and BOREON t-shirt (80 g) are in our women’s trail running t-shirt range.
For accessories, take a trail cap with a peak to protect your face from the sun. Choose category 3 or 4 sunglasses and apply factor 50 sunscreen to exposed skin.
Drinking regularly is one of the best ways to complete a trail run in the heat. Hydrate well beforehand and identify water points before you set off. During your run, aim to drink every 10 to 15 minutes and use aid stations to cool down. Don’t wait until you feel thirsty: that is already a sign of dehydration. Have isotonic drinks or electrolytes (tablets or salty gels) too, to replace lost salts.
To go the distance, you must adapt your effort. Start with a shorter warm-up and set off slowly to let your body adjust. A trail run in hot weather is no time to chase a PB. Instead, dial back your pace, especially on climbs. Do not hesitate to walk through exposed or technical sections, stay in the shade as much as possible and take a break if needed.
How to prevent heat stroke?
Despite precautions, trail runners are not immune to heat stroke. It presents with several symptoms including:
- An abnormal rise in body temperature (often above 40 degrees);
- sudden, intense fatigue;
- severe headaches, nausea, vomiting;
- dizziness, blurred vision or loss of balance;
- hot, dry skin;
- chills or goosebumps;
- mental confusion, slurred or incoherent speech, aggressiveness;
- loss of consciousness.
To avoid heatstroke, follow the basic precautions. Pace yourself from the first few minutes: your body is already working to regulate its temperature. Drink regularly and alternate water with electrolytes. Cool down by wetting the back of your neck or your neck gaiter whenever you can. A good hydration pack, with easily accessible flasks or a hydration bladder, can also make a difference. Aim to run early in the morning or in the evening. Avoid the hottest hours (between 11 am and 4 pm) and stick to shaded areas where possible.
Throughout the race, stay tuned to your body. At the first sign of symptoms, stop, move into the shade to cool down and alert the race organisers to your location. Then sip water slowly and rest completely, while staying under supervision. If the situation does not improve quickly, do not wait—seek medical assistance.
With a little foresight, careful attention to your body and the right gear, trail running in the heat is entirely achievable. By adopting the right habits, you can fully enjoy the race without taking unnecessary risks. Good luck!
