You might think heatstroke and other heat-related conditions only happen to older or ill-conditioned people. Sorry, I got news for ya, bub. According to the American Academy of Family Physicians, “Exertional heatstroke is a condition primarily affecting younger, active persons. It is characterized by rapid onset - developing in hours - and frequently is associated with high core temperatures.” Heat stroke can also creep up on a person over the course of several days. Conditions accumulate in the body to create a perfect internal storm. 
Heat exhaustion occurs when the body’s temperature control system is overloaded. Many factors can contribute to this, and a person can experience it even if their body temperature is only slightly above normal. The mechanism can be compromised and the body fails to cool itself, causing body temps to rise rapidly. 
Though it might not be as serious as heat stroke, you don’t want to risk getting heat exhaustion, either. It is a small step from there to heat stroke, which can kill quickly. About fifteen years ago, I got heat exhaustion while driving railway spikes on the job. The heat index was over 125 degrees Fahrenheit. I was ill for several days after, and let me tell you, since then I can’t deal with the heat as well as I used to.  
Good news is, being proactive and understanding how heat works can go a long way in preventing these problems. 
desert in the summer
If this is where you have to train in the summer, you'll want to keep reading. [Photo courtesy Pixabay]

Interpreting Weather Reports

Most people are aware of the wind-chill chart. In cold weather, low temperatures coupled with the speed of the wind cause the cooling effect, which means the temperature you feel is lower than the measured temperature. 
Check this out (quoting the National Weather Service):
"Since heat index values were devised for shady, light wind conditions, exposure to full sunshine can increase heat index values by up to 15 degrees Fahrenheit. Also, strong winds, particularly with very hot, dry air, can be extremely hazardous."
Training with little clothing in direct sunlight exposes you to a greater heat index by up to 15 degrees Fahrenheit. Additionally, strong gusts of wind can turn hot conditions into a convection oven. The wind multiplies the effects of the heat, just like wind-chill but in reverse. The wind and dry air suck moisture off your skin so rapidly you often do not realize how much you are sweating. This can cause a person to fail to realize they need to drink more water because they don’t feel sweaty. 
Knowing the temperature isn’t enough. You have to take all these variables into account to make your training as safe as possible. Your local weather report might say it's 90 degrees Fahrenheit. However, in your backyard it might be 100 degrees in the shade. So if you train in the direct sunlight with shorts and a tank top or no shirt, you could be exposed to a heat index of at least 115 degrees. That’s 25 degrees higher than the local weather report, and it can put you in danger if you are not extremely careful. 
Here’s a handy chart to refer to to help translate all these variables. For those of us who live in a much dryer climate, use this version instead. Keep this chart handy or keep some sort of app on your techno-gizmo so you can track conditions. Even the northern states here in the United States can reach temperatures of 90-95 degrees Fahrenheit and higher. What people do not realize is that at 96 degress and a relative humidity of 65 percent (which is not rare in eastern states) the heat index is 121 degrees. 
Training under such conditions is asking for a death sentence. Relative humidity of about 65-70% prevents the body from cooling by evaporation. So even at lower temperatures, higher humidity can exacerbate training conditions to unbearable levels. 
Finally, don’t assume the local weather report of temperature is accurate for exactly where you are training. Temperatures can easily vary by 10 degrees across even a relatively small area of just a square mile. Buy a good thermometer and learn to use these charts. It can save your life or someone you care about. 

If You Must Train in the Heat…

Now that I’ve discussed the scary stuff, let’s get into how you can continue to safely train in the hot summer months. Some simple tips:
  • Drink plenty of water. Don’t be an idiot and think you can adapt to dehydration. You can’t.
  • Use electrolytes
  • Educate yourself on hyponatremia and also hypernatremia
  • Train in the shade. 
  • Train indoors during the worst heat/humidity of the day. Train outside in the morning. 
  • Use a water spray bottle if the humidity is relatively low. This works really well for those who just don’t seem to sweat much and overheat easily. 
  • Soak your clothing with water in dryer conditions. 
  • Be intelligent and pay attention to heat-index charts. If it’s too dangerous to train outside, then train indoors. 
  • Cover up with loose-fitting clothing, which catches the breeze easier than tight-fitting clothes.
  • Cover your head with a wet bandana. As the water evaporates, it provides a wonderful cooling effect, especially if you live in a dry desert climate like southern Arizona, where I live.
If you’re smart about it, you will be able to adapt to hot weather just as you would to cold weather. It takes a healthy person about 10-15 training sessions to adapt to higher temperatures. Take it a bit easy in your training for a while as you let your body adapt to the heat. Shorter training sessions can help, too. If you train three times per week for an hour each session, try something different if you train outside. Try breaking that down into thirty-minute sessions spread over six days. Thus, you can train outside with less risk of overheating.
Another option is to train 20-30 minutes in the morning when it’s cooler, then hit a 20-30 minute session later in the day. Spread the load out. Remember, not only are you dealing with the heat index, but you are also creating metabolic heat, which adds to the external heat load upon your body. 
Train smart. Train safe. If you are a coach or a trainer, you had better know what you are doing and monitor your clients closely. And if you train alone, forewarned is forearmed. There is a time to push things and a time to play it smart and live to battle another day. 
Next article, I’ll jump into some ideas for training through the summer.
Got a summer race coming up? You'll want to check this out:
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