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?
Just like hiking in hot weather, trail running involves several hazards. The most critical is heat stroke. Also known as severe hyperthermia, it occurs when the body can no longer regulate its temperature. It can lead to organ failure, and even death in the most severe cases.
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
While running in extreme heat carries risks, a few tips will help reduce them. First, learn how to dress for a trail run. We recommend choosing technical clothing and avoiding cotton, which traps moisture. Opt for lightweight, breathable and quick-drying trail t-shirts and trail shorts. Light colours are also recommended as they absorb less heat.
When it comes to accessories, pack trail caps with a visor to protect your face from the sun. Choose Category 3 or 4 sunglasses and an SPF 50 sun cream to apply to exposed areas.
Consistent hydration is one of the best ways to succeed in a trail run in hot conditions. Hydrate well beforehand and locate water points along the route before starting. During exertion, remember to drink every 10 to 15 minutes and take advantage of aid stations to cool down. Never wait until you are thirsty, as thirst is already a sign of dehydration. Also use isotonic drinks or electrolytes (tablets, electrolyte gels) to make up for sodium loss.
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 prevent heat stroke, apply all the essential guidelines. Pace yourself right from the start, as your body is already working hard to regulate its temperature. Drink regularly and alternate water with electrolytes. Cool off by splashing water on your neck or buff whenever possible. A solid hydration vest with easily accessible flasks or a water bladder can also make all the difference. Finally, it is best to head out running early in the morning or in the evening. Avoid the hottest hours (between 11 am and 4 pm) and seek out shaded trails.
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!
