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Summer Shape-Up: 5 Tips to Stay Cool When Exercising in Heat

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When you're shaping up for summer, one thing is guaranteed: heat.

And even if you don't plan on doing a triathlon or marathon in hot weather, high temperatures can make your workouts uncomfortable, inhibit performance, cause dehydration, and leave you feeling literally and figuratively under the weather.

Why does hot weather throw such a wrench into our workouts?

As soon as you start exercising in the heat, you force your body to circulate blood out to the skin, where it can be cooled. But this can suck precious, oxygen-delivering blood away from your working muscles, while also lowering the amount of blood your heart can pump with each beat. Add this to the fact that you're also losing blood volume via the fluid in your sweat, and what you have is increased demand on an already-stressed heart.

As your body's blood becomes a precious commodity and your heart is forced to work harder, your heart rate rises uncomfortably, your breathing becomes difficult, your blood pressure can drop, and your core temperature rises. Eventually, you will reach a temperature and blood pressure at which your brain sends a message to your body to stop, and at that point exercise goes from being uncomfortable and difficult, to simply impossible.

So how can you keep cool when you're exercising in the heat? Here are five tips:

1) Train for Higher Blood Volume
Also known as "heat acclimation," the process of training your body to have more blood involves a combination of consistent training and heat exposure. As summer rolls in, gradual exposure to exercising in hot conditions is one of the best ways to train your body to heat acclimation. Start with 10-20 minutes of jogging, bicycling, or brisk walking in the mid-morning or afternoon heat, and add just a few minutes each day you get used to the temperatures. When you combine this with drinking big gulps of water whenever you begin to get thirsty, your body will gradually increase blood volume to help you cool.

2) Sweat Better
Did you know that athletes produce more sweat? This is a cooling mechanism that they develop during heat exposure. When I'm preparing for a big race in hot weather, I visit the steam room or sauna and simply sit for 20-30 minutes while sweating profusely. Two to three weeks before a triathlon in hot weather, I'll increase my heat time to 45 minutes (just make sure you stay safe, and exit the sauna if you get light-headed or extremely uncomfortable). That way, when you have to exercise in the heat, your body will be used to it.

3) Lose Less Salt
Not only do you sweat more as you get fitter and increase your heat exposure, but you also lose fewer precious electrolytes in your sweat! Your body actually learns to hold on to the salts that you require for muscle contractions. When you become accustomed to hot exercise conditions, your body will automatically decrease the salt you produce in your sweat. So limit sodium intake during exercise, don't drink too many sports drinks (no matter what the commercials say), and as you learn to live and exercise with lower salt intake, your body will excrete less salt during exercise. A great resource to learn more about this concept is a new book by Tim Noakes, called Waterlogged.

4) Increase Salt Availability
There's one exception to the rule above. If you're planning on going out to exercise in the heat for a long time, such as competing in a hot weather marathon or triathlon, you may need to salt your food for a few days prior to your event, or like me, use some kind of a liquid mineral supplement a few times a day to ensure that your electrolyte levels are topped off. Especially if you're doing a good job not eating too much salt, and avoiding lots of high sodium processed and packaged foods, this extra salt during the week of a hot event can give your body extra sodium stores to rely on during exercise.

5) Keep Your Body Cool
There are many strategies you can implement to keep your core temperature cool during hot weather exercise. Here are five of the most effective:

  • Dump water on your head and face. The sensation of cold can also give you a refreshing feeling that can override the overheating message your body is sending to your brain. The colder the water, the better -- and if I am planning on a long run or bike ride in the heat, I'll even do a cold bath or cold shower beforehand so that I start with a lower temperature.
  • Wear clothing that breathes. A cotton t-shirt will not breathe well, and may make you feel even hotter. Exercise clothing that is designed for hot weather exercise is made of fabric that wicks away sweat and allows your skin to do a better job cooling your body. Look for clothing with synthetic fabrics specifically designed for exercise, such as polyesters, micro-fibers, and ultra-thin wool.
  • Drink. The best and easiest way to maintain blood volume that is necessary for body cooling is to drink water that is as cold as possible whenever you become thirsty. Do not wait until after you've become thirsty to drink, but also don't drink a bunch of water if you're not even thirsty. Simply listen to your body. If you have a long run planned, consider carrying a water bottle with you.
  • Use ice. Ice can help keep water cold during warm weather exercise, and can also be shoved down the front or back of your shirt to lower your temperature. In addition, you can chew on ice to cool your core, and if you really want to geek out on staying cool, you can wear specially designed arm-cooling sleeves, vests, and gloves!
  • Limit sun exposure. If you're exercising in the heat, try to stay under trees, near fences, behind buildings, and in as many shady spots as possible, since direct sun exposure can significantly affect your body temperature.

Ultimately, your body is able to adapt to hot conditions, but you need to give it gradual exposure to the heat, adequate water, and smart use of the strategies I described above for an added hot weather advantage.

Missed It? You can still participate in the 30-Day Summer Shape Up:

Ben Greenfield is the author of Get-Fit Guy's Guide to Achieving Your Ideal Body -- A Workout Plan for Your Unique Shape.

For more by Ben Greenfield, click here.

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