Trail running is a demanding race in the heart of nature. And when temperatures rise, every step can become a real test. To avoid putting yourself at risk, it's important to learn how to manage these conditions. Here's everything you need to know to run a trail in the heat.
What are the dangers of running a trail in the heat?
As with hiking in the heat, trail running carries several dangers. 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 even death in the most severe cases.
With intense sunshine in summer, particularly in the mountains or on open terrain, sunburn presents another risk. It can indeed worsen the sensation of heat and contribute to the onset of heatstroke.
Another extremely common risk is dehydration. With exertion and sweating, you can lose several liters of water during a race. If this loss isn't compensated, you risk loss of concentration, digestive issues, faintness, or even kidney problems in the long term. And it's not just water. A lack of salt can also catch you out, causing nausea, headaches and impaired consciousness.
Heat directly affects the brain. During an effort as intense as a trail, your concentration and reflexes can become impaired. The risk of falling — and therefore injury — increases significantly.
Tips for running in intense heat
Even though running in intense heat carries risks, a few practical tips can help reduce them. First, learn how to dress for a trail. We recommend choosing technical fabric clothing and avoiding cotton, which retains moisture. Go for lightweight, breathable, quick-drying trail t-shirts and trail shorts. Light colours are also recommended, as they absorb less heat.
On the accessories front, equip yourself with trail caps with a visor to shield your face from the sun. Choose sunglasses of category 3 or 4 and a SPF 50 sunscreen to apply to exposed areas.
Staying properly hydrated is one of the best ways to complete a trail in the heat. Drink well in advance and identify water points before the start. During the effort, remember to drink every 10 to 15 minutes and use aid stations to cool down. Don't wait until you feel thirsty — that's already a sign of dehydration. Also consume isotonic drinks or electrolytes (tablets, salted gels) to offset salt loss.
To keep going for the full race, you need to manage your effort. Start with a shorter warm-up and begin at a slow pace to get your body accustomed. A trail in the heat is not the right time to chase a personal best. Instead, reduce your pace, especially on climbs. Don't hesitate to walk through exposed or technical sections, seek shade as much as possible, and take a break if needed.
How to avoid heatstroke?
Despite all precautions, trail runners are not immune to heatstroke. It presents with several symptoms, including:
- An abnormal rise in body temperature (often above 40 degrees);
- sudden and intense fatigue;
- severe headaches, nausea, vomiting;
- dizziness, a feeling of blurred vision or loss of balance;
- hot and dry skin;
- chills or goosebumps;
- mental confusion, incoherent speech, aggression;
- loss of consciousness.
To avoid heatstroke, apply all the basic precautions. Take care of yourself from the very first minutes, as your body is already working to maintain its temperature. Drink regularly and alternate water with electrolytes. Cool yourself down by wetting your neck or your buff whenever possible. A good hydration pack, with easily accessible flasks or a water bladder, can also make a real difference. Finally, it's best to head out early in the morning or in the evening. Avoid the hottest hours (between 11am and 4pm) and stick to shaded areas.
Throughout the race, stay attuned to how your body feels. At the first sign of symptoms, stop, find shade to cool your body down and alert the race organisation to your position. Then drink in small sips and give your body complete rest, while remaining under supervision. If the situation does not improve quickly, don't wait — seek medical assistance.
With a little preparation, plenty of body awareness and the right kit, running a trail in the heat is entirely achievable. By adopting the right habits, you can enjoy the race to the full without taking unnecessary risks. Good luck!
