Be Cool

The first time I ever hiked into the backcountry of Arizona’s Grand Canyon, I was struck by what seemed to be an oddly placed, though prominent sign at the trailhead. The sign was dominated by a photograph of a smiling young woman in athletic clothing. Below the picture was an ominous warning to be prepared for the looming threat of the severe summer temperatures of the canyon. Conditions that had taken the life of this elite athlete. Though we had taken every advisable precaution, the reality of this danger weighed heavily. We often hear the frightening reports of athletes, adventurers, and laborers succumbing to the dangerous effects of summer heat and humidity. How does this happen? How can it be anticipated or prevented? The answer is found in understanding your body.

Your body is wonderfully designed to maintain a temperature of 98.6 degrees F. (+/- 1.8 degrees). It is tremendously efficient in doing so. Because your cells and organs function best in this range, it uses several mechanisms to cool itself when exposed to high heat environments. But it also relies on factors outside of the body. You don’t need to be a scientist to understand these principals; you experience them every day! Let’s take a quick look:

1. Evaporation: You know how the saying goes, “Never let them see you sweat.” Ok, I admit there are times when sweat betrays our stress and anxiety, but it is also the badge of hard work and play! Physical exertion turns your body into a natural furnace generating remarkable amounts of heat. And while your body makes numerous adjustments, sweat and heavy breathing are your body’s most effective means of cooling itself. As water from your skin and breath vaporizes into the atmosphere, you are cooled! So work, play, and wear your sweat proudly!
2. Radiation: Hey, hot stuff! This cooling is literally the result of heatwaves emanating directly from your body into the cooler atmosphere. This will be most efficient while wearing lightweight (breathable) clothing or leaving skin uncovered. This would obviously be counterproductive if a bit of cooling is exchanged for a sunburn! So if out in the sun, use sunblock on any exposed areas. Interestingly, there is some evidence that sunblock can enhance radiative cooling by blocking the constricting effect of UV rays on blood vessels in the skin. 
3. Convection: Ahhh, nothing like a cool summer breeze. This is when the heat is carried away from your body by either moving air or liquid. Think of a breeze, a fan, or the cool mist of a waterfall. As an aside, you won’t catch a cold if you sleep under a fan or AC…you will just be cool.
4. Conduction: So I guess Mom knew what she was doing when she put that cool rag on our forehead when we had a fever. This works because with conduction there is a transfer of heat when two items are in direct contact. Just think of how cold your skin feels after applying ice to an injured body part. This is specifically because the heat from your body is transferred to the ice pack (melting the ice), not that the cold was transferred to the skin! So when you see sun-bathers lumbering from their beach towel to the pool or surf for their interval dip, you are witnessing conductive cooling at its best.

So if you ever find yourself stuck on a deserted tropical island, you will certainly be safest when sweaty, in tattered clothes, under the cover of a shady palm tree while enjoying a southerly breeze (and holding an ice-cold drink if available!) And just like that, you are now an expert in evaporation, radiation, convection, and conduction.

So if the body is so good at this, how do we get into trouble? Well, as your working muscles generate heat, your body immediately responds by diverting blood to the skin where the increased heat can be transferred away from your body. Being well hydrated ensures that you can make sufficient sweat for evaporation while maintaining the necessary blood flow to and from the hard-working muscles, organs, and skin.

So, what’s the problem? Well, radiation, convection, and conduction become ineffective when the air temperature is higher than your body’s core temperature. Have you ever tried to cool off in front of a hairdryer? Remember, heat transfers towards cool. Things get especially bad if severe humidity prevents evaporation. So the extreme heat and humidity of late summer set the stage for trouble.

So what can you do?

• Hydrate.

1. 1. • Hydrate before, during, and after exercise. Consuming electrolyte-containing solutions during and after exercise can be useful in replacing “salt” losses through sweat. If you are dehydrated, you will be unable to efficiently carry heat away from your core, make sweat for cooling, and feed your muscles and organs the fuel and oxygen they need.
      • Look at your urine! Your ability to make urine is one of the best measures of how well hydrated you are. The better hydrated you are the clearer your urine is. Yellow means CAUTION! If your urine is any shade darker than a light, clear yellow, you are already dehydrated. Remember— clear pee, you are free; a little yellow, you better mellow.

• Acclimate. 

1. 1. • Work towards maintaining a base level of fitness prior to entering the hottest and most humid months. When fit, your body will work much more efficiently, generating less internal heat.
      • Gradually increase your exposure to exercising in the high heat and humidity. This enables your body to adapt, tolerate higher core temperatures, and become more efficient at its cooling strategies. 

• Listen.

1. 1. • Whispers: Your body is talking to you and you are the only one who can hear it! When your body’s ability to work and cool are being overwhelmed you will begin to receive distress signals. Beyond the normal strain and fatigue you can expect from exertion, these distress signals will always make you feel “sick.” Listed below are a few examples. If you experience any of these, immediately tell someone, get out of the sun, and move to a safe, cool area:

1. 1. 1. 1. Unsatisfied thirst
         2. Headache
         3. Feeling faint
         4. Increased sweating with chills
         5. Muscle cramping
         6. Abdominal cramping
         7. Generalized weakness

1. 1. • Shouts: If you ignore your body’s early signals, things can get serious fast. So, if you or anyone with you faints or becomes confused or disoriented, it is essential that you seek emergency care immediately! 

So hydrate, acclimate, and listen. Get out there, move and enjoy the beauty of summer days outdoors! Your body knows what to do!