Behind the Forecast: How heat and humidity can make exercise dangerous

LOUISVILLE, Ky. (WAVE) - While exercising is vital year-round, exercising in the summer heat and humidity can wreak havoc on our bodies.

Our bodies cool off when our sweat evaporates off our skin, taking heat with it. Intense heat and humidity interrupt that process and can cause two major problems in our bodies. They help to increase core body temperature and cause dehydration.

In less humid air, our sweat can easily evaporate. However, when humidity is high, it is nearly impossible for our sweat to evaporate because the atmosphere is so saturated with moisture there’s nowhere for ours to go.

Hyperthermia, increased body temperature, can decrease our muscle’s endurance; this reduces a muscle’s ability to contract repeatedly or move in a sustained manner for an extended time. Just a rise of five to six degrees can cause serious issues. Hyperthermia can also lead to the body using its stored energy more quickly and cause a decrease in blood flow to the heart. Reduced blood flow to the heart limits the amount of oxygenated blood being pumped back into our muscles.

According to experts, up to two to eight percent of body weight can be lost during high-intensity exercise (marathon runners can see a drop of eight to 10 percent). Sometimes drinking plenty of liquids can’t always keep up with that. Dehydration may occur before the typical cramps set in.

To combat the effects of heat and humidity, professional athletes sometimes try to acclimatize themselves to a climate before a tournament or other major sports event. For some, that can happen in as little as a week to 10 days.

Here are the CDC’s tips for exercising in hot weather.

• Limit outdoor activity, especially during the middle of the day when the sun is hottest.
• Wear and reapply sunscreen as indicated on the package.
• Schedule workouts and practices earlier or later in the day when the temperature is cooler.
• Pace activity. Start activities slow and pick up the pace gradually.
• Drink more water than usual, and don’t wait until you’re thirsty to drink more. Muscle cramping may be an early sign of heat-related illness.
• Monitor a teammate’s condition, and have someone do the same for you.
• Wear loose, lightweight, light-colored clothing.

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