This article originally appeared in Issue 4 of our magazine.

The summer months bring with them the warmth and humidity we’ve come to expect. Most of us look forward to being outside and enjoying the nice weather. Whether it’s that half-marathon you’d like to cross off your bucket list or maybe just a short hike, it’s no surprise people are more active in the summer months.

Hot and humid weather combined with increased activity has no doubt contributed to incidents of heat-related illnesses. Hyperthermia occurs when your body’s core temperature reaches levels greatly above normal (98.6 degrees F), which would begin at about 100 degrees F. Depending on the severity of hyperthermia, it can bring about several other critical issues, including dehydration, heat exhaustion, and heatstroke. These can occur with and without exercise — however, we’ll focus here on exercise-related heat illnesses. We’ll look at what you can do to better prepare yourself, and what to do if it’s too late. Understanding practical steps you can take is imperative to your safety.

Exertional Heatstroke

Exertional (yes, that’s a word!) heatstroke is a life-threatening illness that occurs when the body is unable to dissipate the heat it is storing and reaches critical temperatures, according to the Health Care of Homeless Persons manual. This leads to a breakdown of the body’s heat-control mechanisms.

Signs:

  • Disorientation
  • Nausea
  • Vomiting
  • Diarrhea
  • Severe dizziness
  • Weakness
  • Extreme thirst
  • Disorientation
  • Convulsions
  • Coma

Predisposing Factors:

  • Obesity
  • Dehydration
  • Low physical fitness level
  • Lack of heat acclimatization

Exertional Heat Exhaustion

Exertional heat exhaustion is significant weakness that occurs when too much fluid and electrolytes are lost through sweating. This generally leads to an inability to continue exercise.

Signs:

  • Fatigue
  • Thirst
  • Malaise
  • Shortness of breath
  • Dizziness
  • Headache
  • Nausea
  • Vomiting
  • Diarrhea
  • Profuse sweating

Predisposing Factors:

  • Dehydration
  • High body mass
  • Lack of heat acclimatization

Above: According to the Journal of Athletic Training, on average, your body temperature increases 0.4 degrees F for every percent of body mass lost through sweating in hot and humid environments.

Before Activity

Environment

To stay safe in hot and humid conditions, you really have to know your environment. Dry heat conditions, such as in a desert, typically have high ambient temperatures, but low humidity. Conditions like this allow for heat to dissipate effectively through evaporation. By contrast, humid weather can be especially dangerous because moisture in the air doesn’t allow sweat to evaporate well, keeping the sweat rate high without the attendant cooling effect.

Another factor to consider is time of day. Solar radiation peaks around noon, which is when sunburn occurs the quickest. The highest temperatures, however, usually occur around 3 to 4 p.m., depending on cloud cover. Wear sunscreen when appropriate, and do your best to avoid these hotter times.

Clothing Options

The clothes you wear can make a significant difference in how you tolerate the heat. Clothing creates a microenvironment between your skin and the fabric, which will affect your body’s ability to dissipate heat through sweating. Clothing that absorbs sweat will not allow that heat to be transferred away from your body, making matters worse, according to Advanced Environmental Exercise Physiology. As more heat is generated through activity, it creates a situation where heat builds up without being released.

First, limit the amount of clothing you’re wearing. More skin exposure results in better heat dissipation. Next, look for light-colored, moisture-wicking fabric. Light-colored clothes reflect more of the heat radiating from the sun, and moisture-wicking fabric allows sweat to be transferred to the material, where it will evaporate. Cotton or wool retains heat by trapping sweat in the fabric. If you only have cotton garments, look for something loose-fitting. This allows more airflow to your skin and increases evaporative heat loss.

Pre-cooling

Pre-cooling your body is another effective way to safely lengthen the amount of time it takes for your body to reach critical temperatures, according to the Journal of Strength and Conditioning Research. Some options include spending some time in an air-conditioned building or vehicle, placing a cold wet towel on the back of your neck or drinking cool water. Regardless of the method, this can lengthen the time you can safely spend time in this type of environment.

Hydration

Hydration in hot and humid environments cannot be stressed enough. Since sweating is your body’s primary method of cooling, dehydration can occur during hyperthermic conditions if you aren’t regularly drinking.

An accurate way to see if you’re dehydrated is by observing your urine color. Urine that is clear may indicate you are overhydrated, while pale yellow, somewhat resembling lemonade, would represent adequate hydration. When urine color is darker, similar to apple juice, it’s a pretty good indicator that you are dehydrated, and fluid intake is highly recommended at that point. Look to drink about 16 to 20 ounces of water one-and-a-half to two hours before activity.

To prevent dehydration during activity, drink roughly 7 to 10 ounces every 20 to 30 minutes.

During Activity

Activity should also be altered in these environments to reduce the likelihood of developing heat illnesses. It’s far too common for people to wait until there are warning signs before they reduce intensity — you should try your best to avoid this situation. Reduce the intensity at which you’ll be working, especially if you aren’t accustomed to this type of weather. When possible, take short breaks to avoid reaching high temperatures.

To prevent dehydration during activity, drink roughly 7 to 10 ounces every 20 to 30 minutes. Many of the popular sports drinks contain electrolytes, which are lost in sweat. If you’re planning on being active for 75 minutes or longer, a sports drink may be beneficial. Otherwise, water will do just fine.

After Activity

It’s very important to rehydrate after being out in the heat. To figure out how much to drink, you would ideally measure your bodyweight before and after being active or in the environment. Following this guideline, drink between 20 and 24 ounces for every pound of bodyweight that you lost. Whether it’s water or a sports drink, opt for something cold to help bring down your core temperature faster.

Treatment

So, what if it’s too late? First and foremost, try to reduce as many environmental variables as possible by moving indoors or to a shaded area. The most effective cooling method is immersion in cool water, but not cold water. Water that is too cold can cause shock. The problem is that it’s not practical for most people. A more realistic option would be placing cold wet towels on the back of your neck, splashing cold water on your body, or the use of fans to circulate air toward you. If symptoms are severe, such as in the case of exertional heatstroke, medical assistance is highly recommended to quickly replace the lost fluids and reduce temperatures.

Heat can create a very dangerous situation if you’re not ready. Know the environment, plan accordingly, and be aware of the warning signs. Adequate preparation makes all the difference — sometimes between life and death.

About the Author

Ryne Gioviano, M.S.Ed., NSCA-CPT is the owner of Achieve Personal Training & Lifestyle Design. He holds a master’s degree in exercise physiology and is a certified personal trainer through the National Strength and Conditioning Association. For more information, visit www.achieve-personaltraining.com. You can find Ryne on Twitter and Instagram at @RGioviano.


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