Why are we talking about heat illness in the middle of winter?

Heat illness is a fascinating topic that typically hinges itself on a single concept – hydration.  Drink more water!

After a 5-hour hike where I exerted myself every step of the way, dragging 25lbs of gear on my back, keeping my heart rate elevated, I had to ask myself a fundamental question.  Why after 5 hours did I not take a single sip of water?  Not one, yet I felt great.  And a dirty little secret is I drank coffee the night before and on the way to the trail — no water.  And that means there is no better time to talk about heat illness than the dead of winter.

Hydration isn’t the key

Most of us have were taught that hydration is the key to fighting heat illness.  And if that were the case, then I would have dropped dead after 5 hours on the trail.  But I didn’t.  Why not?  Because the real key is heat.  Yes, heat.  Hence the name heat illness.  So why is it that you can do the same calorie burning, heat producing workout in the winter without taking a sip of water.  The answer is in the impact of temperature on the body.

This quote nicely summarizes the issue of hydration:

“Dehydration has also not been shown to be the cause of heatstroke. The body temperature of athletes is only indirectly affected by hydration with exercise intensity being the main determinant. Body temperature tends to increase with exercise intensity. When forced to exercise without adequate fluid replacement, humans can raise their body temperatures through “adaptive heterothermy.”
In such situations, the body tends to sweat less as the higher body temperature makes it easier for the body to dissipate its heat via convection to the much cooler environment. The greater the difference in temperatures, the faster the body can conduct this process. This lessens the need to sweat, and thus serves to conserve body water. The most common cause of collapse after exercise is exercise-associated postural hypotension — not dehydration — as many health care providers covering sports events are prone to assume. Exercise-associated postural hypotension is a form of vasovagal fainting that occurs in susceptible individuals within seconds or minutes after exercise. The treatment is simply to put the athlete’s head down in the Trendelenburg position.”
Lear more about hydration in the book Endurance:

What does heat do to our body

Heat or rather high temperatures affect our body by vibrating the molecules (atoms) which generates more space between them.  Expansion occurs.  This expansion dilates blood vessels, increase heart rate, and generally swells our entire body.  The purpose of this expansion and increase in heart rate is to bring blood to the surface of our skin rapidly to evaporate the heat thru a process called convection.

Just as when you get a fever, high body temperatures run the risk of cooking your brain, so do high body temperatures increase the risk of heart-related trouble.  The heart rate increases to quickly dissipate hot blood, so the muscle doesn’t cook –  a fried heart is not a good thing.  So to control body temps, we use cold compresses – hence temperature variances

 

Temperature variances are the key

As we looked at above “the body tends to sweat less as the higher body temperature makes it easier for the body to dissipate its heat via convection to the much cooler environment. The greater the difference in temperatures, the faster the body can conduct this process. This lessens the need to sweat, and thus serves to conserve body water.”  

The body only utilizes maximum water when it cannot cool itself through other processes. That is why shade, cold air conditioning and other tactics such as administrative controls (working in cooler times of the day, working at night, job rotation, etc.) are so crucial to heat illness prevention.  The higher the variance between body temperature and outside temperature, the less hydration becomes a concern.

Why hydration leads to fuzzy decision making

It’s not really hydration that leads to fuzzy logic, but the lack of hydration.  As the body loses water, it also loses electrolytes.  Electrolytes are substances that conduct electricity in the body such as Sodium, Potassium, Calcium and Magnesium.  And it is that electricity that makes our muscles contract allowing our brain to send messages and speeds up our CPU (Brain).

Electrolytes like sodium and potassium help us retain our fluid levels, which translate to blood volumes, the flow of blood to muscles at the same rate and the rate at which we sweat.  These electrolytes help the body absorb the water into the body. Hence you pee less.  More pee = less hydrated.  Sodium also helps keep our thirst mechanism working correctly, meaning it doesn’t shut off early, so we can more accurately hydrate.

How does all this lead to fuzzy logic?  Simple, with a lack of electrolytes (electricity) the brain doesn’t fire off all the messages.  Or if it does, they don’t all make it across the synapses due to a lack of power.  And it is the lack that starts the poor decision making which ultimately leads to heat illnesses and potentially death.

What should you do to fight heat illness

Let’s face it, we need water and hydration is important, but it really is the last line of defense against this deadly illness.  You should take serious steps to plan the work.  And not just day to day, but year by year.

  • Plan the outdoor projects that require a lot of activity, exertion and manpower during the winter months.
  • Ensure that you have enough manpower to rotate jobs
  • Ensure that you have enough shade available.
  • Plant shade trees where you can
  • Reduce radiant heat sources where possible, this includes asphalt, artificial turf, etc.

 

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