Running in the Heat

The biggest environmental performance killer for the runner is heat. You can dress for cold weather runs and still perform well, but just a slight increase in temperature and your performance suffers. 

Take marathon runners for example. When the temperature rises from 50 degrees fahrenheit to 60 degrees, marathoners slow by roughly 3-7% percent. That means a 3:45:00 marathoner could expect to slow by well over 5 minutes! 

The reason heat is such a challenge is that when you run, your muscles produce heat. In fact, the enzymes in the energy production processes work best when the muscle temperature is slightly elevated above resting temperature. That’s why we “warm up” before a hard workout or race. 

We sweat to remove muscle heat, but add environmental heat, and the body has to balance two things – the performance you want from your running and keeping the body from getting overheated. Frankly, the latter will always dominate. The brain’s top priority is keeping you alive. The body does its best to deal with the heat, but it can only do so much when your body temperature climbs. 

Daily hydration is critical when living and training in hot and/or humid environments in order to maintain your plasma volume.

Luckily, an easy way to monitor your daily hydration is via your urine color. Dark colored urine indicates you are dehydrated. Optimal hydration is when your urine is light yellow. This color chart shows the optimal color of your urine.

What to Drink

“What do I drink?” is a common question. Outside of meals, I suggest water w/ electrolytes and/or citrus slices.  Water alone is fine, but too much plain water may cause you to urinate out precious electrolytes. 

A variety of electrolyte supplements (powders or tablets) are available that you can add to plain water. Experiment to see which one you like best. 

Choose Your Run Time and Route

A no-brainer for hot weather training is to select the coolest part of the day for your runs. This is pretty easy for morning runners as the temperature is typically lower in the morning compared to the afternoon. However for afternoon runners, changing the normal training time is a must if you want to avoid the greatest decrease in performance. 

Runners who would wait till later in the day (usually 8pm or later) when it was less humid. It’s kind of a “pick your poison” deal, and you may have to experiment to see which is less impactful to your running. 

Another strategy to stay cooler and safer when running in heat is route selection. Choosing a shady and preferably non-asphalt route reduces heat from the sun and paved surface. Running near waterways and low areas is typically cooler though sometimes more humid. 

From a safety standpoint, never run far away from help in hot conditions. You never know when heat illness will strike, so keep your hot runs where you can easily get help if you need it.  An ideal route has access to fluids/water fountains, and you can get into air conditioning immediately if you get overheated. 

I tend to run short loops, so I’m never too far away from extra fluids and help. I do not go for a long run on a remote trail when it’s hot. Best to stay close to civilization or have bail out options on longer runs in case I run into issues.

Lastly, don’t start a run when you are already hot.  You want your body temperature low before starting a run in the heat. If you’re already hot, you’re likely dehydrated as well.  The run will go poorly, and you’ll need extra recovery time.  

Gear up by stripping down

Compared to most sports, runners are lucky! Other than a good pair of shoes, you don’t need a lot of expensive equipment. Although you will need a few articles of clothing, made of comfortable and breathable cloth, for running in the heat. 

Carry Fluids

Runners think about carrying fluids on long runs, but when training in the heat, you should carry fluids even on short, easy runs. The fluid intake is not so much for the run itself as it is to get a head start on rehydration after the run. Drink as much as your GI system will tolerate while running and know that you are one step ahead on your rehydration post-run.

If you don’t like to carry fluids, then choose routes where you can stop at water fountains or even stash fluids along your route before you run. 

How to Pick your Hydration Gear

The three main types of hydration gear are 1) hand-held water bottles, 2) a waist pack with water bottles or a bladder and 3) a backpack-style (aka hydration vest) bottle/bladder carrier. 

More on next ……

• Water weight loss and heat acclamation