published Thursday, July 26th, 2012

Experts answer common questions about exercising during hot weather

Thomas LaRocco works out at Chattanooga CrossFit on West Main Street. Experts say sweating, the body’s built-in mechanism for keeping cool, is good when exercising, but profuse perspiration can be a sign you’re overheating.
Thomas LaRocco works out at Chattanooga CrossFit on West Main Street. Experts say sweating, the body’s built-in mechanism for keeping cool, is good when exercising, but profuse perspiration can be a sign you’re overheating.
Photo by Alyson Wright.

In the record-breaking heat Chattanooga has experienced this summer, even walking to the mailbox can feel like an endurance sport. With proper preparation, however, physicians and researchers say there is no reason to avoid exercising, even on the hottest days.

To answer our questions, we checked in with:

Brendan McDermott, a professor in the University of Tennessee at Chattanooga health and human performance department who specializes in the study of how heat and hydration issues affect the body.

Dr. Tiku Bhutwala, an internal medicine physician with Parkridge Medical Group-Battlefield.

Bhutwala fielded our first questions about the hazards of hot-weather exercise.

Q: What are the health risks of exercising during hotter weather?

A: Working out in any kind of excessive heat is risky. Individuals who are going to have the most difficulty are people who ... have a low physical fitness level. People who don't have acclimatization to this [weather] and suddenly decide to go run a 10K are going to have serious problems.

People on certain medications will have difficulties. Medications that affect sweating or blood pressure or kidney function or diuretics are the most common villains in that process.

Lastly, there are certain individuals who have certain genetic problems who have difficulty as well, such as people who have sweating problems.

Q: Should I speak with my doctor before exercising in hot weather, or is it a judgment call?

A: I would say it's both. There are some individuals who should consider contacting their physician, including people who are on certain medications and individuals who have

pre-existing medical problems as well as the elderly or frail or those with low physical fitness levels. If nothing else, the physician can tell you what you can do to prevent heat stroke or heat exhaustion from affecting you.

For the average, healthy, middle-aged adult, they should be fine as long as they are acclimatized and have some sort of level of conditioning. Conditioning goes a long way in heat management.

Q: What are the warning signs that I'm too hot when I'm exercising?

A: Typically, the key is to listen to your body. You're confused or having double vision or your balance or coordination are not as good as they should be. Your body will be breathing faster, and [you may] notice some skin color changes to being redder or warmer and perhaps profuse sweating and muscle cramps. Headaches are usually a big sign.

Typically, you'll have gastro intestinal symptoms ... diarrhea or vomiting symptoms that force you to stop.

That's if your core body temperature rises. If you're able to keep your core body temperature down, you may have none of those symptoms.

Q: How can I tell the difference between normal fatigue and heat exhaustion or heat stroke?

A: The person who is not conditioned is going to feel those symptoms in the early or middle part of their run, not at the end like most people would. Some of the other body symptoms like headache or vomiting or diarrhea ... are distinct feelings that something isn't right. I might feel hot after a three- or four-mile run, but I don't feel like I'm going to pass out.

Q: What steps should I take, once I realize I'm overheated?

A: No. 1, stop the activity; get yourself out of the intense heat. All your targets should be to try to reduce your core body temperature. It's not just hydration but hydrating with something that has a good electrolyte combination, such as Powerade or another sports drink.

Cooling down with water [by] putting it on your face or neck is a wise idea. That's the fastest way to begin cooling down. Sit down and maybe elevate the legs, if you feel like you're going to pass out. That will keep fluid circulating to the brain.

Prevention is a bigger topic. That comes down to knowing your body, planning your exercise, conditioning yourself well and hydrating prior to working out and making sure the medications you take don't predispose you to problems.

McDermott continued the conversation with insights into the physiology of summer exercise.

Q: When should I hydrate during hot weather? Before, during or after exercise?

A: All of the above, but whatever works for the individual is what is going to work. Obviously, you want to start out exercise hydrated because you'll sweat and lose fluids during the activity. For some people who sweat a lot, it's tough to keep up. If you're starting behind the hydration game, you're only going to get more dehydrated throughout the exercise.

You want to take breaks periodically during the activity and replace fluids and keep up with your sweat rate during exercise. After the exercise, you want to hydrate immediately to recover more quickly and more easily reap the benefits of the exercise.

Q: Are sports drinks better for me than water when it's hot?

A: When it's warmer, you're losing more sweat, and when that happens, you're losing sodium and chloride and potassium and other electrolytes. Sports drinks replace those, but they don't replace exactly what you're losing.

I tell people that if you're an endurance athlete or are doing something for more than an hour outdoors in the heat, sports drinks do offer a hydration advantage. The advantage is they replace electrolytes and sugars, which you're burning if you're exercising outside, but they also promote thirst, so if you drink them, you're more likely to be hydrated because you're liable to drink more.

Q: Why do I feel less fatigued exercising in the heat than I did earlier in the summer?

A: Really, it comes down to what you're used to. Scientifically, it takes about 10 to 14 days to acclimatize to [the heat] and see all the benefits from it, and some are seen in as little as five days.

Heat acclimatization, at least for me, is the most impressive physiologic thing that the human body does. Anybody who is otherwise healthy can conceivably exercise at most environmental temperatures. The time that heat illnesses are most common are when people aren't used to it, such as during a heat wave ... when your system is somewhat shocked.

Q: Does the importance of a pre-workout routine or post-workout cool-down increase during hotter weather?

A: Not at all. A warm-up, in and of itself, is not really necessary when it's so hot outside. In my mind, a warm-up's athletic goal is to warm up your muscles, so if it's that hot outside and you run around for two minutes, you're pretty much as warmed up as you would be doing a full warm-up when it's 75 degrees outside.

If you want to do a cool-down after exercise by stretching or those types of things, that's fine, but the longer you're outside, your chances of increasing your temperature beyond what is healthy increases. If you do cool down, cool down inside.

Q: What should I be wearing during hot-weather exercise to stay cool?

A: There is no scientific evidence that anything leads to more efficient thermal regulation or that moisture wicking is effective in dissipating heat or heat transfer. Ultimately, wearing a cotton T-shirt is going to be the same as wearing a $60, souped-up moisture-wicking shirt. Furthermore, there's no evidence that I'm aware of that dark clothing will lead to any sort of heat gain beyond what light clothing does.

I would recommend wearing whatever you feel comfortable in. If there's a placebo effect to wearing the $60 shirt and you feel better wearing it, go ahead and wear it.

about Casey Phillips...

Casey Phillips has worked as a features reporter in the Life department since May 2007. He writes about entertainment, consumer technology, animals and news of the weird. Casey hails from Knoxville and earned a bachelor of science degree in journalism and a bachelor of arts in German from Middle Tennessee State University, where he worked as the features editor for the student newspaper, Sidelines. Casey's writing has earned numerous accolades, including first and second place ...

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