If you are training this summer for REVEL Big Cottonwood or Canyon City, or are maintaining your base mileage for REVEL Mt Charleston or Rockies, you are dealing with training in the summer heat.

There are many common tips to help runners train during hot summer months: wearing cooler, moisture wicking garments; running in early morning or late evening hours; and finding shaded areas to run.

But there are two important tips that runners often overlook when training in the heart: proper hydration, and electrolyte replacement.

Running in the heat means dehydration and loss of electrolytes, both of which can have moderate to severe impact on your performance. In order to continue training in the summer without suffering the potentially debilitating effects of dehydration and electrolyte loss, it helps to understand how and why heat, dehydration, and electrolyte loss affect your running.

Heat, Running, and Dehydration

During exercise, heat dispersion is your body’s way of keeping you cool by increasing blood flow to the skin for conductive cooling. Meanwhile, your muscles are like small furnaces that produce heat when you convert fuel to energy while running. Your brain detects this rise in body temperature, and triggers your body’s sweat glands for evaporative cooling. The water that helps cool you down - sweat - comes mostly from the blood, so the end result is decreased blood volume as you dehydrate. In lay, non-medical terms, the loss of water results in “thicker” blood.

At the same time, your muscles need oxygen to keep working. The need for oxygen means a need for a continued flow of blood to the muscles.

Putting all this together, what you end up with is a situation where your blood is getting “thicker” as you sweat, meaning it is less efficient at flowing to the skin and muscles. Your body is less able to cool itself by conductive cooling, and is less efficient at delivering oxygen to the working muscles.

So how do heat and humidity affect all of this? A hot day triggers more sweating. A humid day means your evaporative cooling system is not working very efficiently, because moisture in the air suppresses the evaporation of sweat on your skin. You are left with a situation where your body finds it harder to meet the demands being placed upon it. Your muscles need oxygen-filled blood in order to keep you running; your skin needs blood to help keep the body cool; and in the meantime dehydration from sweating means your blood is less and less capable of performing both tasks.

Furthermore, your body responds to decreased blood volume by decreasing blood flow and suppressing sweat in order to conserve bodily fluids. In turn, your muscles simply cannot perform well without adequate oxygen, your sweating declines, and your body temperature can rise to dangerous levels.

Even if you are able to continue running in the heat, research indicates that most people - not just runners - are in a constant state of dehydration. With regular exercise in the heat, that dehydration is worsened. In turn, your overall performance as a runner suffers. You might feel sluggish, suffer from headaches and nausea, lower GI problems, rapid pulse, chills, and muscle cramps. These symptoms can last for days, not just during or immediately after a run.

Over the course of several days, this constant dehydration, inadequate rehydration, and subsequent chronic dehydration, can lead to poor training and very difficult runs.

Pre-hydration and Rehydration

“Dehydration” simply means “water loss.” It’s going to happen when you run. The important thing to remember is that no matter how much you drink during a summer run, it can be extremely difficult to keep up with the amount of lost fluid. For every pound of water lost during exercise, you need at least 16 ounces of fluid replacement - and that is the minimum.

Of course, most runners drink from coolers, drinking fountains or their own water bottles immediately after or during runs to quench thirst. That is fine, but do not forego a rehydration plan just because you chugged down a full bottle of water or sports drink immediately after a run. First quench your thirst, then slowly rehydrate over the course of several hours.

You can counter the effects of the dehydration by “pre-hydrating” before a run, stopping to drink at regular intervals during a run, and then rehydrating after a run.

Before you run, “pre-hydrating” is the specific act of preparing yourself for exercise and the normal dehydration that accompanies exercise. At a minimum, drink 8-12 cups of water throughout the day, especially during summer months. At least one hour before a run, drink 12-16 ounces of water.

During a run, drink 6-8 ounces every 15 minutes, even if you are not thirsty.

After you run, it can take anywhere from 24-48 hours to completely rehydrate. Remember that your body is only going to absorb 24-28 ounces of water every hour after exercise. If you have lost 2, 3, 4 or more pounds of sweat during a workout, it will take several hours just to absorb that much water, assuming that you drink enough to catch up. Even then, you will begin to lose some of that fluid through digestion, so you’ve got to continue drinking regularly for many hours after exercise.

The Importance of Electrolytes

Electrolytes are minerals in your bodily fluids that carry electrical charges. They exist in your blood, inside the cells, and in the fluid surrounding the cells. Your nerve cells and muscle cells use electrolytes to carry electrical impulses. Thus, when your brain sends an “electronic signal” to your muscles to contract or relax, the electrolytes carry that signal from the nerves to the muscle cells.

Two of the major electrolytes in the human body – sodium and potassium – are critical for muscle functions, but are lost through exercise and sweat. Together, these two electrolytes perform essential functions for the contraction and relaxation of muscles. With heavy fluid loss through sweating, the loss of electrolytes can result in cramping. As dehydration continues, entire muscle groups become fatigued and begin to fail.

Replacement of electrolytes is important when training in hot weather. The most common way that runners replace electrolytes during exercise is by consuming sports drinks. Also, some gels and electrolyte tablets typically have very high quantities of sodium and potassium. There is no single answer to the questions of how to replace electrolytes, and when. Sweat rates and electrolyte loss-rates are different from person to person. It is a process of trial and error, which means you should experiment with electrolyte replacement techniques to find the ones that work best for you.

Summary

There is no question that running in summer months will mean slower overall paces, tougher finishes to your workouts, and a lot of fatigue associated with dehydration. You should expect to find it harder to maintain your training paces and overall mileage during hot weather. That’s perfectly normal.

However, you can improve your training by adhering to a hydration plan that includes pre-workout hydration and post-workout rehydration. You are asking a lot of your body when you run in hot summer weather. Likewise, your body will be asking a lot from you (hydration), and it is important to listen to your body.

Similarly, hydration does not simply mean water. You will lose significant amounts of electrolytes when you train day after day, week after week, in hot weather. Replacing lost electrolytes is critical to maintaining your body’s ability to perform under the demands of training in summer months.

With proper hydration and electrolyte replacement, you will be better able to maintain your training regimen as your work your way towards an awesome race day at your REVEL events!