Exercising in the Heat

Is warmer weather finally approaching? Is it time for a tropical vacation? Do you still want to get some exercise in and stay on top of your routine? If so, here are a few things you should understand about exercising in the heat to stay safe and maximize your workout.

Various body adaptations occur as we adjust to warmer temperatures during exercise. Some things happen immediately, while other adaptations occur over time as you continue to get used to exercising in warmer temperatures. Here are the basic, major adaptations that occur.

HEART RATE, STROKE VOLUME, & BLOOD VOLUME

Short Term: Initially, your heart will work harder when you begin exercising in the heat as it attempts to maintain homeostasis. You may feel more sluggish exercising at the same intensities in the heat than you do at lower temperatures. This is because your body is working harder to stay cool and fuel your muscles in the heat.

Long Term: Once you adapt to the higher temperatures, your heart will be under less stress. Your heart rate will actually decrease but you’ll still be able to work at higher intensities. This allows you to perform better because as your heart rate decreases, your stroke volume, which is the amount of blood sent out with each contraction of your ventricles, increases.

Additionally, with an increased plasma volume, your body will be able to send more blood to the skin’s surface to cool you down, and also more can be sent to the muscles to allow them to work at their best.

BLOOD VESSELS, SKIN, SWEATING, & IONS

Short Term: Your body will immediately begin to sweat more in the heat, as your core temperature rises. Sweating is how your body tries to maintain homeostasis. In this case, homeostasis looks like your body attempting to stay within the ideal core temperature range. To do this, your body will sweat more as it tries to cool itself down.

In order to sweat, your body will increase skin and muscle vasodilation. This means your blood vessels widen, or dilate, in order to allow more blood to flow near the skin’s surface, where heat can be lost via convection, evaporation, and radiation.

Initially, sweating more than normal leads to a lot of water loss, which can lead to dehydration. You can lose more than 3 liters of water per hour while exercising in the heat, depending on duration and intensity. If you aren’t careful about drinking a lot of water or another beverage containing some electrolytes before and after a workout, this dehydration can lead to hyperthermia. Hyperthermia is a serious issue wherein your body is unable to cool itself. You might become dizzy, faint, and nauseous.

Long Term: Sweat is a mixture of mostly water and some salt. As your body adapts more to exercising in the heat, your kidneys will get better at holding onto the salt and excreting mostly just the water. This is a good adaptation because if you sweat a lot and lose too much salt, it can cause ion imbalances which can lead to cramping in your muscles.

The temperature at which you begin to sweat will lower as well. This allows your blood vessels to dilate sooner and your body to begin sweating, and cooling itself, sooner. This maximizes the benefits of sweating and lets you cool faster.

OTHER THINGS TO NOTE

If you are competing in higher temperatures that you are used to, you might want to give your body a week or two to adjust so that you can perform safely at your best. Your body makes most of these important adaptations in just one week, then results begin to plateau around two weeks.

Wear appropriate clothing that is light or designed to aid in evaporation, like compression clothing.

Additionally, wearing sunscreen will protect you in the sun and help prevent cancer and other skin issues. Wearing sunglasses or a hat is also a good idea to minimize squinting in the sunlight, which can cause headaches and wrinkles if done for a prolonged period of time.

And of course, if you know you’ll be exercising for a while in the heat, be prepared and pack plenty of fluids!

REVIEW

Short & Long Term Adaptations:
1. Blood volume and plasma volume increase
2. Heart rate decreases
3. Vasodilation of blood vessels
4. Sweating more, sooner
5. Retaining salt

Things to Remember:
6. Sun screen
7. Sunglasses/hat
8. Light weight/compression clothes
9. Water/gatorade

Next time you jet off on a tropical vacation or summer comes around and you want to exercise, you need to be smart! Think of how your body works to keep you safe and at your best in warm weather, then respect those limitations and needs, and take care of yourself.

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