There’s something so relaxing about lounging by a pool while the sun’s warm rays shine down on you. The same goes for sitting in a steamy sauna or soaking in a bubbling hot tub. Feeling that warmth is just Very much It’s soothing.
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But your mind may not think so. After all, it’s being forced to work harder.
For every 1 degree increase in your internal body temperature in the heat, your heart rate increases by about 10 beats per minute. This natural response puts additional strain and stress on your heart.
So why does this happen, and what can (or should) be done about it? Let’s calm down with some hard facts from Dr. Michael Crawford, an exercise physiologist who specializes in cardiac rehabilitation.
How does temperature affect heart rate?
Your life depends on your amazing heart and its rhythmic work to pump blood throughout your body. But did you know that the circulatory system that your heart powers also functions as a cooling mechanism?
When you’re hot, your body radiates heat to cool you down, which it does by dilating (or widening) your blood vessels, increasing your heart rate and blood flow, Crawford explains.
As blood rushes through the arteries and veins near the surface of the skin, it loses some heat to the air. This cooling action can cause the amount of blood flow to increase two to four times the normal rate.
“When it’s hot outside, your cardiovascular system really ramps up its efforts to release heat in order to cool you down,” Crawford says, “and as part of that process, your heart has to work harder to circulate blood.”
Sweating effect
Sweating is another way the body beats heat. As each drop of sweat evaporates from the skin, it has a cooling effect.
That’s the good news. The bad news? Sweating puts additional strain on your body by causing you to lose sodium, potassium, and other essential minerals needed by your organs, including your heart. Dehydration from excessive sweating can also put a strain on your heart.
“These losses just put extra strain on the heart,” Crawford said.
Do I need to take precautions against the heat?
Absolutely! Just hanging around in the heat puts extra strain on your heart. If you’re not careful, the scorching temperatures can lead to heat exhaustion, heat stroke, and other heat-related illnesses.
Crawford says being active on a hot day puts your heart at even greater risk. Even if you’re just sitting in a chair, remember that heat puts extra strain on your heart. Going for a training run or mowing the lawn can put even more strain on your heart. Really It puts your heart in a tough situation.
Why? Because you’re essentially making your heart do double duty: keeping you cool and making it work harder to meet the extra physical demands.
So if sweltering heat is in the forecast, try to minimize your time outdoors during the hottest parts of the day, and if you are outdoors, try to focus your activities on the cooler morning and evening hours.
If you plan on being out in the hot sun, do the following on a regular basis:
- Get into the shade.
- Take a break in an air-conditioned room.
- Drink fluids (preferably water) to stay hydrated.
Pay attention to how you’re feeling: “If you feel fatigued or your heart rate increases when you’re hot, don’t ignore it,” advises Crawford. “It’s important to immediately lower your core temperature.”
