The sun is high, pavement shimmers with heat, and the air is still. It's 2 PM, and you're ready with laced shoes, eyes on the road. You want to go, but how do you handle a run in summer heat? Find out here. Before diving into heat management, let's first see what's happening in the body when running in high temperatures.
Why Running in Heat Feels Extra Tough
When you run, legs pump, arms swing, and the body works hard to propel you forward. It feels efficient, but only a fraction of energy goes into movement. The rest becomes heat.
Heat is a byproduct of movement, with up to 70-80% of energy turning to heat. The body must shed this excess to maintain a stable temperature (Duffield & Dawson, 2016). Failure to do so raises body temp, affecting comfort and performance. The body works best within a narrow temp range.
Thankfully, the body has systems to discard excess heat, sending blood near the skin and producing sweat. On still, sunny days, shedding heat becomes harder.
So what do you do? Should you skip the run when temps rise? Fortunately, no. Instead, help the body along. There are simple and effective tips to make your run in the heat more comfortable.
Tip #1 - Train Your Body for Heat
You improve running in heat by practice. It sounds simple, but it works. Studies show after 5–7 days of light training in heat, your body adapts (Philp et al., 2022; Cole et al., 2023). Sweat becomes efficient, heart rate stabilizes, and you maintain body temp better.
Heat training is now popular among elite athletes and serious runners. Exposing the body to heat through training or sauna use enhances its ability to handle heat. Physiological changes include increased plasma volume, higher sweat rate, and improved heat management (Sawka et al., 2011; Périard et al., 2015; Garrett et al., 2012). These adaptations make it easier to endure heat and can enhance performance.
Training your body for heat pays off, especially if you have a major run lined up in summer.
Tip #2 - Dress Lightly and Bright
Clothing matters more than you think. Dark clothes soak up sun rays and heat quickly. Light colors reflect heat, helping maintain lower body temp. Choose white, light gray, or other light shades for sunny runs. A light cap or visor shields your head from direct sun and can make you feel cooler.
Material choice is key. Opt for technical running clothes that wick sweat away and let skin breathe, keeping you dry and cool. Some modern running gear offers cooling features to actively keep the body cool in heat, ideal for frequent sunny runs.
Tip #3 - Drink Wisely
Fluids and electrolytes are crucial when running in heat. Sweating loses water and salts. It's not about drinking most, but drinking smart.
Runs under 1 hour: Usually, staying well-hydrated throughout the day is enough, especially in the hours leading up. Electrolytes before setting off can be beneficial if yousweats a lot. You can also benefit from carrying a small bottle in your hand or pocket, so you can drink along the way.
Trips over 1 hour: Ensure hydration by drinking regularly in the days leading up. Preferably with electrolytes. It's not about drinking extra, but avoiding dehydration. Consider electrolytes before start, and supplement during. A or another way to drink on the go is beneficial.
Remember that too much water without electrolytes can cause stomach issues and reduce performance. Aim for about 400–800 ml of fluid per hour (Sawka et al., 2010), depending on your sweat rate and heat. A drink with some carbohydrate and electrolytes may noticeably improve how you feel and perform.
Tip #4 - Run early and start "cool"
Timing your run matters in summer heat. Early mornings and late evenings are best, with the sun lower and temps more manageable. Avoid 12-3 PM, when the sun is harshest and the asphalt radiates heat.
Help your body before running. Starting “cool” gives your body more time before reaching temps affecting performance. A cool shower, a stay in a cool room, or a cold towel on your neck for a few minutes before departure can make a noticeable difference.
Tip #5 - Seek shade and wind
Route choice can make a big difference in heat. Choose shaded paths like forests, green trails, or between buildings. Soft surfaces like gravel and forest paths reflect less heat than asphalt and often feel more comfortable.
Consider wind direction too. A light headwind can help evaporate sweat and cool the body. Plan your route to have headwind on the way back, when you're hottest. It might feel tough, but it helps your body more than it slows your pace.
Tip #6 - Adjust pace and expectations
As temps rise, pace should drop. It's not defeat, but smart adjustment. In summer heat, your body works under extra stress. Familiar distances may feel tougher, which is normal. Adjust expectations and pace to match conditions.
As a rule, start by slowing 15–20 seconds per Kilometer. Feel your way. If the body feels strong, increase pace a bit. If it feels heavy, it's okay to take it easy. Use body signals as a guide, not just the watch and your pace. If you're overheating, allow yourself a short break in the shade. It can lower your temp and give your body a little breather, so you can continue running.
On very hot days, rarely chase a new PR. Instead, these are the days to strengthen your ability to run wisely. Respect conditions and listen to your body, and you can still enjoy great runs in the sun.
Ready, set, summer run!
You're there again. Sun blazing, air shimmering, and little shade. But now you know what to do. You've planned the route, brought a sip of water with electrolytes, slowed down a bit, and picked the light, white shirt over the black one. Enjoy the run – and remember sunscreen.
References:
Cole et al. (2023). Short-term heat acclimation for aging populations. PLOS ONE, 18(3).
Duffield & Dawson (2016). Cooling interventions for athletes. Temperature, 3(2).
Garrett et al. (2012). Short-term heat acclimation in athletes. Eur J Appl Physiol, 112(5).
Périard etal. (2015). Heat acclimation mechanisms and applications. Scand J Med Sci Sports, 25(S1).
Philp et al. (2022). Heat acclimation and rowing performance. PLOS ONE, 17(9).
Sawka et al. (2007). Exercise and fluid replacement. Med Sci Sports Exerc, 39(2).
Sawka et al. (2011). Exercise performance in the heat. Compr Physiol, 1(4).
