The heat is on!

What a hot summer we have had in Middle Tennessee this year!  I've been without my heart rate monitor for most of the summer.  I lost it in the locker room earlier this year and finally got around to ordering a replacement.  This morning was my first opportunity to run in the opressive heat with my HR monitor on.  The effect the heat had on my body was surprising.  A run, that under normal conditions should have been easy, had my heart pounding away like I was running speed intervals on the track. That got me to thinking that some of you out there may be struggling through the opressive heat as well, and could use some helpful information.  So... no spiritual analogies this time around (unless you want to come up with some on your own).  Just some info on how your body handles heat and some suggestions on how you can beat it.

When God designed the human body, He designed it to be quite adaptable... even giving us a built-in cooling system.  Part of that cooling system is the blood.  Blood does a lot of things in the body: it carries fuel and oxygen to our cells, and carries away waste and toxins.  Another thing that it does is help regulate our internal temperature... much like antifreeze in a car engine.  When the temperature starts to rise, your body begins to sweat.  As the sweat evaporates, it cools off the blood that is near the surface of your skin.  As the cooled blood is circulated throughout the body, it keeps your internal temperature from rising too high.  That system works pretty well unless an outside phenomenon interferes with it. That outside phenomenon is called humididy.  Yes, the dreaded "H" word that all of us in the south have to deal with.

Humidity is the measure of water vapor in the air.  The higher the humidity, the more water vapor in the air.  As the humidity rises, the rate at which our sweat evaporates slows down.  On really humid days, our sweat doesn't evaporate at all.  No evaporization, no cooling of the blood.  No cooling of the blood, no regulating of our internal body temperature.  So what happens then?

Well, as our body temperature starts to rise, our heart starts beating faster to try to get more cooled blood circulating through the body.  And since the blood isn't really cooled, the body produces more sweat to try to cool off more... and our hearts keep beating faster... more sweat... higher heart rate... more sweat - you get the picture.  Eventually, because of all the sweat that you are producing, your body becomes dehydrated... which makes the heart's job all the more challenging.  Eventually, if your internal body temperature does not get under control, you will begin to suffer heat exhaustion, which can then lead to heat stroke.  Not a pretty picture.  So, what can we do to help prevent that unpleasant cycle.  Here are a few suggestions:

• Get rid of the cotton. Cotton absorbs moisture.  If you have a soaking wet cotton shirt clinging to your body, then your sweat is not able to evaporate from your skin.  Instead, invest in clothes made with "wicking" material.  Wicking material is designed to "wick" moisture away from your skin, allowing it to evaporate, and keep you relatively cool.
• The more exposed skin, the better. Wear as little clothing as you can while staying modest and legal :).  If your skin is exposed to the open air, it increases the chances that your sweat is going to do what it is supposed to do.
• Run in the dawn and twilight hours when the sun is low on the horizon... and if you can't do that, try to find routes with a lot of shade.
• Stay hydrated. You are going to sweat, and you are going to lose water from your body.  Don't wait until 30 minutes before a run to chug-a-lug a gallon of water.  Your body can only process so much water at once. Drink fluids throughout the day... and take water breaks during your run as well.
• Know when to stop.  Read up on the symptoms of dehydration and heat exaustion/heat stroke (see links above) and know when you need to shut down your run.  Heat exhaustion or heat stroke is not something you should attempt to run through.

So keep these things in mind as you head out in the heat.  Let's run the race, smart.