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How to Recognize Heat Exhaustion

Updated: Aug 2, 2020

This past weekend I had the unfortunate experience of giving myself heat illness while on a mountain bike ride. Sunday was a particularly warm day, with high humidity, but I came prepared with a Camelbak full of ice water, a system for taking routine breaks, and a goal of just going out for a leisurely ride. All was going according to plan, and I felt hot but not overheated, until the halfway point of the ride. (Isn’t that how it always happens? The incident occurs when you are furthest away from the car?) Halfway through the ride I had a sudden wave of dizziness followed by stomach cramps and nausea. I figured it may just be some neck pain and lunch talking to me, and tried to ride through it. But then the vomiting started. At this point I knew we were in serious territory and stopped and used my water to cool my head and neck. Thankfully, with frequent rest breaks, I was able to make it back safely, but I wanted to take this opportunity to share the warning signs with everyone so it doesn’t happen to you.

The signs and symptoms of heat exhaustion are as follows(1):

1. Moist, clammy skin

2. Profuse sweating

3. Muscle fatigue (general) and/or cramps

4. Nausea or related gastrointestinal distress

5. Severe thirst

6. Headache

7. Increased respiratory rate and rapid pulse

8. Body temperature up to 104*F

Now, if you are an endurance athlete then you are well aware that half of the above symptoms are normal responses to exercise in the heat. I have bolded the non-normal responses to exercise in the heat. We are unable to take a body temperature on a run, usually, so our symptoms are then confined to nausea, severe thirst, and headache. These are your warning signs that things are escalating too quickly.

If you do not cease exercise at this point, we can get into heat stroke territory. Here are the symptoms for heat stroke(1):

1. Sweating may stop

2. Hot, dry, or clammy skin

3. Mental confusion of loss of consciousness

4. Gastrointestinal distress, including nausea and vomiting

5. Severe motor disturbances and loss of coordination

6. Rapid and strong pulse

7. Rectal temperature higher than 104*F

Now, these symptoms are more readily alarming to most people. These are the more recognizable symptoms that cause concern. But here’s the problem: how do you know when you are shifting from heat exhaustion into heat stroke? Answer: you don’t. As you saw from my personal experience, I had some symptoms that would fall under the heat stroke category. It should be noted that heat stroke can cause permanent neurological damage and even death. This is not something we want to play around with!

If you notice heat exhaustion symptoms in yourself or a training partner, what should you do? Here are some suggestions(1):

1. Stop exercise immediately

2. Give fluids if not nauseated

3. Move to cool place

4. Lie down with legs elevated

5. Loosen clothing and cool with wet towels or ice packs

6. If not recovered in 30 minutes, get medical attention

7. Do not exercise the rest of the day

Now, you may be thinking to yourself: Ryan, you did not do all of these things. And in that you are correct. I should have stopped exercise and called for assistance to get off the trail. However, since I was training alone, options for getting off the trail were minimal aside from riding out. This brings me to another point: when training in the heat, try to avoid training alone! Things could have gone very, very poorly for me if my condition had worsened. Thankfully, I was able to get to the river and dunk myself for some cooling, but it was still a scary experience. And I have to say humbling, as well. I grew up in Florida and have trained in the heat my entire life. I know these symptoms and what to do when they occur. Yet, heat illness does not discriminate or care how much you “know” or how much “experience” you have.

If you notice the more serious heat stroke symptoms, medical services should be called, and the person should be immersed in cold water. Heat stroke can progress rapidly and we have seen too many college football players die over the past few years as a result of poor medical response.

Let my example from this past weekend give you caution when training in the heat. Your best plans mean nothing when physiology goes haywire. Put the pride aside and get help when your body is asking for it. Try to avoid training alone and let people know where you will be and when you will be back. I am certainly going to take this incident to heart and put my pride aside if I experience these symptoms again!

Let’s stay safe out there!



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