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Running in the Heat: Understanding the Performance Impact

Running in the heat

Running in the Heat:

Understanding the Performance Impact

As summer temperatures rise, running in the heat becomes a reality for many distance runners. While warm weather can be inviting, it also presents unique challenges that can impact your performance and safety.

Understanding how heat affects your body and adapting your training accordingly is essential for staying healthy and achieving your running goals. In this blog post, we’ll explore the performance impact of running in the heat and provide tips to help you manage these conditions effectively.

How Heat Affects Running Performance

  1. Increased Heart Rate

When you run in the heat, your body works harder to cool itself down. This leads to an increased heart rate, even at slower paces. Your cardiovascular system has to pump more blood to the skin to dissipate heat, which can leave less blood available for your muscles.

As a result, you might find it harder to maintain your usual pace.

  1. Dehydration and Electrolyte Loss

Sweating is your body’s primary cooling mechanism. However, excessive sweating can lead to dehydration and electrolyte imbalances. Dehydration decreases blood volume, which further strains your cardiovascular system and can lead to decreased performance and increased risk of heat-related illnesses.

  1. Reduced Muscle Efficiency

Heat can reduce muscle efficiency by causing fatigue more quickly. High temperatures increase the rate at which your muscles break down glycogen, leading to earlier depletion of your energy stores.

This can result in slower times and decreased endurance.

  1. Increased Perceived Effort

Running in the heat feels harder because your body is under more stress. The perceived effort of running in high temperatures is significantly higher than running in cooler conditions. This can be discouraging and affect your motivation and mental toughness. Remember; It is not you, it is the heat!

It is not you, is it the heat

Adapting Your Training to the Heat

  1. Acclimatization

Gradually acclimating to the heat can help your body adapt and improve your performance. Start with shorter, easier runs during the hottest parts of the day and slowly increase the duration and intensity as your body becomes more accustomed to the heat.

  1. Hydration Strategies

Staying properly hydrated is crucial. Drink water throughout the day and use electrolyte drinks during and after your runs to replace lost fluids and minerals. Aim to drink before you feel thirsty and monitor the color of your urine to ensure you’re staying hydrated.

  1. Adjust Your Pace

Accept that your pace will be slower in the heat. Use effort-based training rather than focusing solely on pace. Pay attention to how your body feels and adjust your intensity accordingly. Running by perceived effort or heart rate can help you maintain appropriate intensity levels without overexerting yourself.

RPE - Rate of Perceived exertion

  1. Choose the Right Time and Place

Run during the cooler parts of the day, such as early morning or late evening, to avoid the peak heat. Seek shaded routes or trails with plenty of tree cover to minimize direct sun exposure.

  1. Wear Appropriate Gear

Lightweight, moisture-wicking clothing can help keep you cool. Choose light-colored apparel to reflect the sun’s rays, and wear a hat and sunglasses for added protection. Don’t forget to apply sunscreen to exposed skin to prevent sunburn.

  1. Listen to Your Body

Be aware of the signs of heat-related illnesses, such as heat exhaustion and heat stroke. Symptoms include dizziness, nausea, excessive sweating, and confusion. If you experience any of these symptoms, stop running immediately, seek shade, and hydrate.

Don't start a run dehydrated

Performance Expectations

It’s important to adjust your performance expectations when running in the heat. Studies have shown that performance decreases as temperatures rise. According to research published in the Journal of Applied Physiology, running performance can decline by up to 20% in extreme heat (Galloway, S. D., & Maughan, R. J., 1997). Understanding this can help you stay motivated and avoid frustration.


Running in the heat presents challenges, but with the right strategies, you can continue to train effectively and safely. Gradually acclimate to the heat, stay hydrated, adjust your pace, and listen to your body. By taking these steps, you can maintain your fitness and enjoy running throughout the summer months.

Remember, the key to successful heat training is to respect the conditions and prioritize your health and well-being.


  1. Galloway, S. D., & Maughan, R. J. (1997). "Effects of ambient temperature on the capacity to perform prolonged cycle exercise in man." Journal of Applied Physiology.

  2. I also really like this post:

  3. What to know about summer running.

  4. The crucial role of hydration for runners. By adapting to the heat and managing your expectations, you can continue to enjoy your running journey, even in the hottest months.

Stay cool, stay safe, and HAPPY RUNNING!!


If any need more help with your hydration - it may be time for a Sweat Test.

Sweat test for runners


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