Training in the summer heat


It’s starting to get warm around here, and I love it! I love warm summer time and the warm weather that comes with it.  It helps that as a teacher, I don’t work.  I enjoy training in this weather as well.  I will take hot summer weather over cold winter weather any day. Training in the heat definitely comes with its own troubles and challenges, so you need to take steps to ensure your training safely.  The good news is, heat training can have additional training benefits.

sweat sparkle

How does heat affect your run?

When you run in the heat, you are probably aware that your body perspires more. The perspiration isn’t what cools you down, but the evaporation of sweat. *Nerd Alert* Middle School Science Lesson* Sweat is a liquid.  As those liquid molecules heat up on the surface of our skin, they begin to move more rapidly.  Heat is energy. The heat from your body is transferred to those droplets of sweat on the surface of your skin.  The increased energy begins to break the bonds that hold the liquid together and the liquid changes states of matter, from a liquid to a gas.  This is evaporation.  As the sweat evaporates, the heat (energy) is removed and your body cools. Humidity levels can impact how quickly that sweat evaporates, slowing down the cooling process.

As your body sweats more, your body also increases blood flow to the surface area of your skin.  Blood contains plasma, which is released when you sweat.  This means you are losing water and electrolytes, while lowering blood volume levels in hot weather.  The loss of plasma also changes the viscosity of your blood, making it more difficult for your heart to move the blood efficiently through the body.  Your muscles rely on the movement of blood to receive oxygen and other nutrients as you exercise. This increases stress on your heart. As your body needs more resources to keep you cool, your muscles begin to get less priority over those needed resources, such as oxygen. Your body will shift from aerobic to anaerobic more quickly, which is why a normal pace will feel much more difficult. This increases the stress load of the workout on the body.

Safety Issues

The increase of needs on the body, can put your body in a more dangerous situation when you fail to recognize symptoms.  I have had runs that I have called quits early because of nausea, dizziness and issues with perspiration.  The key for safety to listening to your body and taking steps to keep yourself safe.  Some of the main concerns for heat training include,

Heat Cramps and Heat Exhaustion- Both are brought on by dehydration and imbalances of electrolytes.  Staying properly hydrated is key.  It is recommended that you include water and sport drinks to help balance your fluid and electrolytes.

Hyponatremia- This is caused by taking in too much water.  This increase of water can dilute the sodium levels in the body.  This becomes a greater concerns on longer runs.  Again, including sport drink and water or taking salt tabs can help prevent this situation.

Heat Stroke- Occurs when your internal body temperature rises to unsafe levels.  If you become dizzy, disoriented or stop sweating you need to begin cooling your body immediately.

Again, the key is listening to your body and having a safety plan in place.   Running with a partner or carry your phone is a good idea.  It’s always better to go ahead and call a run early if you think you may be struggling with heat illnesses.

Tips for running in the heat

Again, I love running through the summer months and would choose heat training over cold weather every time.  There are steps you can take to increase your comfort and safety.  Here are some things you can do

  • Build up slowly– Think of heat training as another training stimulus. Anytime you add a new training stimulus you need to build up slowly.  Decreasing intensity and distance for a couple weeks as the temperature rises, and your body adapts, is a very smart idea.  The good news is, acclimation can be fully developed in 7-14 days.
  • Run Naked! Okay, okay so that’s probably not the best idea. Running in less clothes, is however. Increasing the amount of skin exposed to the air will allow your body to naturally cool itself through the perspiration process, as mentioned above.  Keeping your clothing loose and lightweight will also be very helpful.  Lighter colors will reflect more light, while darker colors absorb it. Choosing lighter colors helps with keeping cool while making you more visible along the road.
  • Plan Ahead-I do a lot of my easy runs in the heat of the day, unless the temperatures become dangerous. However, I try to get my speed work and long runs done in the morning when it is typically cooler.  I also look at the weekly forecast when I am laying out my calendar.  I have flip flopped a few workouts to make sure I wasn’t doing a speed session in unsafe conditions.  Safety will always be priority.  If you can, look for routes that have more shade.  Asphalt and concrete are also going to retain more heat over softer surfaces.
  • Hydration– It’s also a good idea to plan your hydration ahead. This can include choosing routes that have access to water along the way, carrying/wearing a hydration-pack, dropping water ahead of time, or my favorite; joining a supported group run. Drink water throughout the day, and for runs longer than an hour, add in a sports drink.
  • Don’t stress over pace– You’re going to need to run more by feel. Remember the purpose of your run?  Your body is working harder in the heat and by getting stuck on a certain pace, instead of running by feel can lead to over training with the added stimulus of heat training.  Your body will have a harder time with active recovery if you are trying to maintain a certain pace that feels harder in the heat. * Check out my post on slowing down your easy run!  As a new runner, it may be difficult to go by feel, another option is using a heat calulator.


Think of heat training as another training stimulus.  It comes with its own advantages.  As your body is acclimating to the heat, it is learning to become more efficient.  This efficiency doesn’t go away when the temperature drops and can have a great impact on your fall racing season.  Just like any other training factor, there needs to be balance and there is a fine line between enough and too much.  I also think there is a great mental component to training through the heat.


What do you prefer to run in, hot or cold weather?


Published by RunCanvas

Hi I am Janell! Avid runner and coach with 14 years of experience helping runners reach their goals. Wondering if working with a running coach is the right choice for you? Run coaching is available for ALL levels and paces. If you run, you are a runner. Hiring a running coach will help you to become stronger and more resilient – both physically and mentally.

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