When we run in normal weather, our core body temperature naturally rises, and our sweat glands produce droplets that carry excess heat to the surface of the skin, where it evaporates. But high heat and humidity prevents sweat from evaporating, so the heat stays on. On a hot and humid day, with no breeze, we lose a way to get rid of our build up body heat, which can make our running more dangerous. Once our body heats up and gets more and more dehydrated, it goes into survival mode, maintaining blood flow to our essential organs (to keep us alive) and to our skin (to regulate temperature). Less blood will flow to our GI tract, which will affect the digestion of our sports drinks and gels, and it might make us feel nauseous. When our body is overheating, we can also get some side stitches, which is also due to our breathing becoming shallow and uneven. Another side effect of running in heat and humidity, is our heart rate escalating due to lack of oxygen, our lungs have to overwork to deliver oxygen throughout our body.
If we keep running in the high heat and humidity, our brain temperature will rise, which causes intense side effects. Our ability to assess our own body temperature will be difficult, we can start feeling chilled and getting goosebumps once we’re overheating. We can start to lose control over the body mechanics, our running form and footsteps, and our mental abilities may start to break down. We can start to feel very dizzy and disoriented. Our body temperature can spike in minutes. Any level of runners can be highly affected by heat and humidity. Competitive runners may be more prone to heat-related illnesses because the faster we run, the more body heat we generate. So running at our normal pace will feel very difficult. Feeling sluggish on a super-hot day doesn’t mean that we lack fitness or mental toughness, it’s our body responding to a stressful environment. Some runners lose more sodium than others, so consuming enough electrolytes according to our body type is essential.
Side Effect of Running in the Heat
- Dehydration can lead to many internal issue, so we have to make sure we consume electrolytes.
- If we feel dizzy or nauseous, we should stop to rehydrate, refuel and rest.
- We have to remember that it can take 2-3 weeks to adapt to higher heat and humidity, so we should tolerate a slower pace and less distance.
- People’s body type reacts differently to high heat and humidity. It can affect some runners more and others. So we should listen to our body type.
Tips to Run in the Heat
- Focus on running effort, not pace- Running in high heat, we need to avoid targeting our normal fast pace. This could cause several health issues, we have to focus on the running effort, how hard it feels.
- Appreciate running in a breeze- It is very common that early in the morning there is no breeze, which affects our oxygenation intensely. So changing our morning run to evening run occasionally, might be very helpful in high heat and humidity.
- Have access to some ice water- Consuming some cold water, or having access to cold water to splash some water on our face or neck and head will help to bring our core temperature down.
- Shade our face- Shading our face and eyes lowers the impact of the high heat. But wearing a regular cap will trap the heat under the cap, affecting our body heat. To wear visor is safer, it allows the head to release heat, or a cap that has a mesh top and back can be safe. To use a cold cap, soak it the night before and place it in the freezer, to wear and icy cap to start a hot run can be helpful.
- Wear sunglasses- Sunglasses will protect not only your eyes, but also your brain. When we run exposed to sun, our eyes squint, and our brain has to work hard and use lots of energy to help save our eyes. Wearing a visor or sunglasses will help relax the face and the eyes, and avoid overusing brain energy.
- Look for courses with shade- Try to plan to run on routes that have as much shade as possible, it makes a huge difference in helping our body not to overheat extremely. If your planning on doing a long run, to start early in the morning before the sun rise can help. The feeling of the strong sun on our arms, legs, and face can make our run much harder.
- Pre-run caffeine- Studies have shown that consuming caffeine prior to a run can improve our performance without impacting hydration. So enjoy a morning coffee, especially iced coffee or latte during the summer.
- Wear lightweight running clothes- To find the proper running gear for high heat and humidity runs is essential. Finding the right brands that use light, dry fit fabrics, to wear tank tops, light shorts can help our body release heat and sweat.
- Don’t forget to smile- To smile while we run can make us feel so much better, it activates more positive thoughts and feelings to support the more negative heat impact on our body.
- Consume electrolytes- To have access to electrolytes will support our intense hot runs. Electrolytes are essential when running in high heat and humidity for more than 60-90 minutes.
- We need to take sips every 1.5-2K according to our running course and elevation.
- Drinking too much high carb drinks while we run in the heat, can cause some stomach issue.
- We need to drink pre-run.
- We need to drink and rehydrate post-run to avoid any stomach issues.
Running in high heat and humidity even at a slower pace, will increase our performance. Training in the heat is an intense endurance training session, once we start running in cooler weather, our performance level will be much higher.
Hydrate, Pace Yourself, Enjoy Running and Training in the Heat!