Keeping Cool on Summer Runs

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How to keep cool (and stay safe) on a hot summer run. Keeping Cool on Summer Runs

Although running in the snow and ice has its own set of dangers, running in the summer is far more dangerous, temperature-wise. You can always add an extra layer in the winter to maintain your body temperature but in the summer, you can only take so much off to keep cool. In addition to wearing as little as possible, there are a number of ways to make a hot summer run bearable and even enjoyable, all the while preventing any ill effects of exercising in the heat.

The Seriousness of Heat-Related Illness

Heat-related illness—heat cramps, heat exhaustion and heat stroke—is caused by an overexposure to heat and the loss of fluids and electrolytes. Dehydration often coincides with heat-related illness. If not attended to promptly, dehydration and heat-related illness can worsen in a short period of time and become life-threatening.

Dehydration, an inadequate level of fluid in the body’s tissues, often is caused by insufficient fluid intake, vomiting, diarrhea, certain kinds of medication and excessive alcohol or caffeine consumption. Initial signs of dehydration include fatigue, weakness, headache, irritability, nausea, dizziness, excessive thirst or dry lips and mouth.

Although heat cramps are the least serious heat-related illness, if ignored, they may be followed by heat exhaustion and heat stroke. The specific cause of heat cramps remains unknown but the common belief is that they are caused by a combination of dehydration and the loss of salt and fluid from excessive sweating. Heat cramps, which are painful muscle spasms, usually occur in the legs and abdomen but can impact any voluntary muscle.

Heat exhaustion is a condition in which fluid lost by the body is not replaced quickly enough. The body then diverts blood away from its surface areas to vital organs such as the heart and brain. Signs of heat exhaustion include cool, pale, or flushed skin, weakness, dizziness, shallow breathing, exhaustion, heavy sweating, headache, nausea, muscles cramps, or a decreasing level of consciousness.

Heat stroke is the most serious of all heat-related illness and is a life-threatening condition that usually happens when people ignore or don’t know the signs of heat exhaustion or do not get medical help quickly enough. Heat stroke occurs when the body systems are overwhelmed by heat and cease functioning. An early symptom of heat stroke—the cessation of sweating—occurs because the body’s fluid levels are extremely low. This lack of sweating causes the body temperature to rise because the body can’t sufficiently cool itself. The increase in body temperature eventually reaches the brain and other vital organs, such as the heart and the kidneys, causing them to fail. Failure to treat heat stroke can lead to convulsions, coma, and death.

Thankfully, with a few adjustments to your regular routine and some precautionary measures, you can continue to exercise safely throughout the heat of the summer months.

When and Where

If your schedule allows, one of the easiest ways to avoid the summer heat is to run during the cooler parts of the day, early in the morning or later in the afternoon or early evening. Typically, air temperatures are hottest between noon and 4:30 p.m. so avoiding that time frame might make a summer run a little more bearable.

Where you run can make a difference between running in relative comfort or not. Routes close to water—the ocean, rivers, lakes or even a narrow stream or small pond—can be cooler because bodies of water heat and cool more slowly than land. Air temperatures near water can be quite a bit cooler so if you are lucky enough to live near a body of water, plan a run there to keep your cool.

If you are landlocked or the closest body of water is too far away, running in the woods or on grass can provide some level of cooling comfort. Anytime you can avoid the hot asphalt, it’s a good idea. Asphalt, brick, stone, and concrete retain and radiate heat and running on pavement or sidewalks amid brick or stone buildings can increase the sweat quotient of a run.

If you have to run on pavement or concrete sidewalks, try to choose a route that is as shady as possible. Even sporadic small tree canopies can provide a little relief from the hot sun.

What to Wear

In addition to wearing the least amount of clothing possible, the choice of fabrics is important when trying to regulate body temperature during a summer run.

Moisture-wicking synthetic fabric will be cooler than cotton clothing. And loose-fitting shorts and tanks or t-shirts will be more comfortable than those that are tighter and more form fitting. In addition, clothing that is light in color will be cooler than those that are dark.

Because covering your head retains body heat, avoid wearing tight-fitting baseball or other types of caps. Opt for a visor that will allow heat to escape from your head instead.

Although it won’t keep you cool, sunscreen is a must on summer runs. Pick one that has an SPF of at least 30 and is sweat proof to ensure that it will protect you until your run is done.

Get Used to It

Not in the “suck it up and get used to it” manner but more in the way of gradually acclimating yourself to running in hot weather.

For the first couple of weeks of hot weather, limit your runs to 30 minutes or less and gradually build up from there. Try to avoid workouts that are intense for the first spell of hot weather until your body gets used to the increase in temperature.

Start slowly as well. Ease into your run by running slower than normal for the first mile or so and then increase the pace. Allowing your body to gradually adjust to the heat is more advantageous than the “baptism by fire” method.

Water, water, and more water

Of course, you know the importance of replacing the fluid you have lost during a run, but it is equally important to hydrate before your run to help prevent dehydration. Even if you aren’t thirsty, try to drink a glass of water each hour prior to a run in hot weather. You will feel better and run better and optimal water storage will help your body’s cooling mechanism work more efficiently.

You might even plan your run in an area where water fountains are available for a mid-run drink (or two!). If water fountains aren’t available, you might consider carrying a water bottle, multiple bottles on a waist belt or a backpack hydration system.

If you don’t usually drink sports drinks, you might consider reaching for one after hot runs lasting an hour or more. At some point, water alone can’t replace the electrolytes and carbohydrates you’ve lost during running. A sports drink or salty food such as nuts or pretzels can help recalibrate your levels and prevent dehydration.

Prior to hot runs, stay away from diuretics such as alcohol and caffeine since they increase urine output. Consuming diuretics in hot weather puts you at greater risk for dehydration. Compounded with a hot, sweaty run, alcohol and caffeine, even from iced tea, can lead to trouble.

To cool yourself down quickly, consider finishing your run at a local pool or swimming hole for a refreshing dip.

Get Ahead of It

Lowering your body temperature before you head out for a run may help you perform better in the heat. Precooling, as it is known, can slow the rate at which your core temperature rises, which can impact how far and how fast you can run in the heat. Precooling can be as easy as staying in an air-conditioned room for an hour before your run, sipping cold beverages, or if you want to go one step further, wearing an ice vest, which is now available for purchase.

Last Tips…Safety First

Listen to your body and err on the side of caution when running in hot weather. To be safe, you may want to stick to a route close to home in case you need to return quickly or tell a family member of friend where you are running and when you will return. In addition, running with your phone is a good idea in case you need to call for help.


  1. American Red Cross, Responding to Emergencies, book
  2. Molly Hurford, 8 Pro Tips to Keep You Cool for a Summertime Run, web site
  3. Jeff Galloway, 20 Tips to Stay Cool on a Summer Run, web site