Staying Safe: Recognizing Heat Illness

Things are heating up again, and earlier than usual!

If you haven’t already heard about the Boston Marathon craziness, you must live under a rock… it was so hot yesterday (high 80s and ruthlessly sunny!) that the Boston Athletic Associaton offered deferment to next year and advised that “only the fittest runners should consider participating.”

About 4,000 runners took the B.A.A.’s advice and did not run the race. Despite some saying that the heat shouldn’t affect the frontrunners, that didn’t seem to be the case. Both 2011 winners succumbed to the heat – Geoffrey Mutai dropped out at mile 18 due to cramps, and Caroline Kilel dropped out at Kenway Square, with only one mile left to go. The winners, Wes Korir and Sharon Cherop, fought through the heat, sun, and cramps, to come in at 2:12:40 and 2:31:50 respectively, making the 2012 race the second slowest since 1985. Many runners sought treatment at local hospitals on a record breaking day – record high temperatures, that is.

Over the winter I talked about hypothermia and how to conquer the cold. Now it’s time to talk about what happens when our bodies overheat and the illnesses that come along with it.

The body is pretty good at regulating its own temperature – we have some amazing tactics in our arsenal to keep ourselves safe. When we get too cold, our body produces heat by shivering and shunting blood to important organs. Our body also has defense mechanisms to keep our body temperature from rising too much. Perspiration helps to cool our bodies by excreting water and other minerals, like sodium, potassium, calcium, and magnesium. When the water evaporates, the body is cooled down.

Medically speaking, hyperthermia refers to a body temperature above the normal range (about 97 – 99.9ºF). Young children, the elderly, and those with certain medical conditions or who are taking certain medications are predisposed to heat illness and should be extra vigilant about the heat, but here we’re more concerned with the kind that comes from exerting yourself in hot and humid conditions.

Heat Cramps & Heat Rash

Heat cramps are muscle spasms and pains, usually in the stomach, side, or legs, that are caused by low salt levels. Those who tend to sweat a lot are more prone to heat cramps, but I’m sure we’ve all experienced these at some point in our athletic pursuits. The key here is to take a break and replenish those lost electrolytes before it’s too late.

Heat rash usually appears as a group of small red bumps, and is nothing more than skin irritation caused by excessive sweating. It’s not so great to look at and mildly annoying, but doesn’t usually cause any more issues than that.

Heat Exhaustion (100º – 104ºF)

Heat exhaustion can effect everyone, but most often occurs in those who aren’t well adjusted to the heat, and especially humidity. When it’s humid outside, the usual sweating mechanism doesn’t work as well, and the body has a more difficult time cooling itself. When the amount of liquid being lost by the body isn’t properly replaced, the body goes into a mild form of compensated volume shock, problems arise.

Dizziness, light-headedness, headache, vomiting, chills, and decreased urination are all symptoms of heat exhaustion. Those with heat exhaustion are usually pale-faced and sweating heavily. If you or a running buddy experience these symptoms in hot and humid environments, stop exercising immediately, remove yourself from the heat as much as possible, drink water, and replenish your electrolytes with Gatorade, Nuun, or even a salty snack if you can stomach it.

Heat Stroke (>105ºF)

Heat stroke can occur with or without the presence of heat exhaustion, but if heat exhaustion goes untreated, or the conditions are gruelingly hot and heavy, it can lead to heat stroke – a very serious and life threatening situation. At this point, the body is producing more heat than it can dump through normal cooling means, and without intervention, the body essentially begins cooking itself. The main concern here is that as body temperature rises, the brain begins to swell, and this is very bad news.

Symptoms of heat stroke include a severely altered mental state (remember  the “umbles”?) sometimes to the point of unconsciousness, very elevated pulse and respiration rate, decreased blood pressure, seizures, and decreased urination. Those with heat stroke have stopped sweating altogether and appear very red.

Heat stroke is nothing to mess with – if you suspect that someone has heat stroke, call for immediate medical assistance (911!) and try to cool them as much possible, through any means.


When outside temperatures rise, our first inclination is to hydrate, hydrate, hydrate! While staying hydrated is key to beating the heat, it is possible to have too much of a good thing. Hyponatremia occurs when the body becomes overhydrated, lacking the necessary electrolytes to properly carry out normal functions. Electrolytes are crucial for the electrical impulses that control virtually every bodily process – without them, we simply can’t function.

Symptoms of hyponatremia can be similar to heat exhaustion – dizziness, nausea, vomiting, headache, and chills – although vital signs (blood pressure, pulse, and respiration rate) are often near normal. Here, they key is normal or even increased urination due to overhydration.

Up to 1 out of every 10 cases of heat related illness can be attributed to hyponatremia. During heavy exercise in a hot environment, drink 16-32 ounces of fluids per hour. It is equally as important to continue consuming food, replenishing the electrolytes lost due to sweating. During intense exercise or endurance activities, an easy way to do this is to use sports drinks like Gatorade or Nuun – frequent small snacks are also helpful!

Staying active during the hotter months is possible and safe, as long as you’re aware of the risks, listen to your body, and recognize signs and symptoms of problems when they first arise. It’s important to treat heat illnesses early when they are more manageable, just like it’s important to treat hypothermia quickly before it progresses.

Stay tuned for more tips to beat the heat this summer – until then, here’s an interesting article about heat and marathoning:

Marathons & Heat: The Facts from Runners World

The Staying Safe series tackles common safety issues in being active and enjoying the outdoors safely and responsibly. Have a suggestion or a topic you’d like to learn more about? Send me an e-mail at!


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