PATHFINDER Horizon | Hot Day? Tips for Summer Training

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It's HOT. Everywhere. Even though summer is coming to an end, the heat will likely continue for quite a bit longer for most of the United States. While summer is a fantastic time to be outside, how do you safely keep up with your training program when the temperatures and humidity are high and it feels like you're exercising on the surface of the sun?

Summer can pose some very real training challenges. Your body can struggle to perform in high heat. Here are some basic, common sense points to consider to set yourself up for a better summer training season.

Hydration & Electrolytes

It's easier than you might think to become dehydrated during your ruck or workout during the summer months. The best decision you can make as an athlete in the summer is to hydrate when you wake up, and frequently throughout the day. A simple way to check is by your urine color: colorless or light yellow? Good job. Dark yellow or amber? Hydrate-hydrate-hydrate.

While thirst is an obvious sign, that's not always the case. Not being thirsty can be a larger problem during outdoor exercise. More obvious signs of increasing dehydration are a noticeable decrease in energy, feeling uneasy, dizzy or feeling the beginnings of a headache. 

If you don't hydrate (water and/or nuun or your favorite *non-caffeinated* electrolyte balanced salt powder), your body temperature can continue to rise. Some serious danger signs: you stop perspiring, you feel nausea and/or have vomited. Emergency medical attention is needed if symptoms such as mental confusion, high body temperature (over 104F), weakness and/or loss of consciousness have occurred.

The American Council on Exercise has suggested the following basic guidelines for drinking water before, during and after exercise:

  • Drink 17-20 ounces of water 2 to 3 hours prior to starting exercise.
  • Drink 8 ounces of water 20-30 minutes before starting your exercise or during your warmup.
  • Drink 7-10 ounces of water every 10-20 minutes during exercise.
  • Drink 8 ounces of water no more than 30 minutes after exercise.

Training on Asphalt & Concrete

Heat rising off asphalt and concrete can increase the temperature significantly. Many urban areas have "urban heat islands" - areas with large expanses of pavement and buildings that can be relatively hotter than the surrounding areas.

According to the EPA, "on a hot, sunny summer day, the sun can heat dry, exposed urban surfaces such as...pavement to temperatures 50-90F hotter than the air, while shaded or moist surfaces - often in more rural surroundings - remain close to air temperatures." Let that sink in - 50-90 degrees HOTTER than the surrounding air temperature.

If you live in a metropolitan area, locate a park, open land or if possible, an area away from the city where temperatures will be cooler to exercise. Mornings are also cooler than evenings due to the slow heat release from urban infrastructure that happens throughout the day.


How many times have you exercised in the summer months and you sweat so much, you felt like you'd been in the shower the whole time? High humidity can be a greater threat than the outdoor temperature. When sweat clings to your body, it affects your body's ability to cool down and maintain a safe temperature. To cool itself, your body sends more blood to circulate through your skin, which leaves less blood to circulate through your muscles, which then increases your heart rate.

Pay close attention to how you feel and what you feel like your body can handle. The result of sweating heavily, not being properly heat acclimated and not hydrating properly can often be a heat-related illness, which can vary in severity from cramps to potentially life-threatening heatstroke.


Sunscreen is an essential component when exercising outdoors. It's especially important during the summer when the UVB rays are stronger and increase your risk of sunburn. (I don't know about you, but I've certainly tried to exercise with a sunburn before, and it was PAINFUL. Any sweat or movement on crispy skin makes you realize how important it is to use sunscreen!)

Look for SPF over 30+ and sweat-proof. Two of my favorites are Supergoop and Blue Lizard, but the best sunscreen is the one you use. Test out a few to see if they affect your sweating. Any sunscreen that reduces the amount of sweat evaporation or sweat production should be used carefully in significant heat conditions while exercising. Which leads us to...

Light-colored clothing & removing your ruck

  • Light-colored, thin clothing keep your body cooler in hot conditions.
  • Extra clothing can trap heat on your body and increase your body temperature.
  • Wearing a ruck can trap heat on a large part of your body, and if you find yourself feeling warm, take a break and remove the ruck. 

Working out at dawn or in the evening

Working out in the morning is pretty great, regardless of weather conditions. You increase your energy for the day, creates calm prior to beginning your workday and your metabolism will get a boost. But during the summer, it also helps you stay cooler. The sun is at its highest intensity from 10 a.m. to 2 p.m. Avoid training during the hottest part of the day. Stay out of direct sunlight when at all possible while training during the summer and move to the shady side of the street.

If you choose to workout in the dark, morning or night, always wear reflective clothing.