David White, MD
Every summer we hear the tragic news that another athlete or outdoor worker has suddenly died while training or working in the heat and humidity of the late August summer. This strikes fear in the hearts of parents, coaches, athletes and laborers alike. But how does this happen? How can it be anticipated or prevented? The answer is found in understanding your body.
Your body is 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. You don’t need to be a scientist to understand these principals; you experience them every day!
Evaporation:
Yep, 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 contrary to the commercials claim that you should “never let them see you sweat,” I say you should sweat with pride!
Radiation:
Hey, hot stuff! These are literally heat waves emanating directly from your uncovered body into the cooler atmosphere; heat leaving your body.
Convection:
Ahhh, nothing like a cool summer breeze. This is when heat is carried away from your body by either moving air or liquid. Think of a breeze, a fan or a cool mist blowing by.
Conduction:
So I guess Mom knew what she was doing when we had a fever and she put that cool rag on our foreheads. This worked by directly transferring heat from our warm bodies to the adjacent cool rag. Just think of how after applying ice to your sprained knee, your skin will feel very cold. This is because the heat from your body was transferred to the ice pack. It wan’t that the cold was transferred to the skin!
So if you find yourself on a deserted island, you will be at your best if you are sweaty and naked on the beach with a southerly breeze and a cold drink in your hand! And there you have it, you are now expert in evaporation, radiation, convection and conduction.
Sweat to Cool Down the Furnace
So if the body is so good at this, how do we get into trouble? Well, during exercise, your muscles generate heat like a furnace. Your body immediately responds by diverting blood to the skin where the increased heat can be transferred away from your body. Being well hydrated also ensures that you can make sufficient sweat for evaporation and that there is plenty of blood flow to 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 hair dryer? Remember, heat transfers towards cool. Things get especially bad if severe humidity prevents evaporation. That’s why the extreme heat and humidity of August set the stage for trouble.
Tips to Stay Hydrated & Healthy
Hydrate. Hydrate before, during and after exercise. 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. 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. Clear pee, you are free. A little yellow, you better mellow.
Acclimate. Work towards maintaining a base level of fitness prior to entering the hottest and most humid months. Your body change 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. Your body is talking to you and you are the only one who can hear it! If you are feeling any of the following, immediately tell someone and get out of the heat and get to a safe, cool area.
– Unsatisfied thirst
– Headache
– Feeling faint
– Increased sweating and chills
– Muscle cramping
– Abdominal cramping
– Weakness
If you or anyone with you faints or becomes confused or disoriented, it is essential that you seek emergency care immediately!
So hydrate, work hard and stay cool. Your body knows what to do.
