United States Department of Veterans Affairs
VA MidSouth Healthcare Network

Feature Article - How Humidity Affects Your Heart

Veterans Health Watch

Hot weather can lead to dehydration, heat exhaustion and heat stroke, but the dangers increase when you add humidity to the mix. When the temperature rises above 70F and the humidity registers Man drinking water more than 70 percent, you need to be on the alert.

Who’s most at risk?

People with high blood pressure, heart disease, lung disease or kidney disease are most vulnerable to the effects of humid conditions, as are those over age 50. Other risk factors that can affect your body’s ability to cool itself include being obese; having poor circulation; following a salt-restricted diet; drinking alcohol; having inefficient sweat glands; and taking diuretics, sedatives, tranquilizers or heart or blood pressure medication.

“Individuals who are at risk should discuss the potential impact of exercise and medication on their health with their physicians,” says Joseph A. Pellecchia, M.D., FACP, chief of staff and cardiologist at VA Medical Center in Huntington.

Exercising in humid weather

Since you generate heat during exercise, humidity can affect your heart rate when you work out, even at cooler temperatures. Your body cools itself by sweating—but only if sweat can evaporate. In humid weather, sweat evaporates more slowly, so your body temperature continues to rise.

What’s more, fluid loss from sweating decreases your blood volume. So while your heart is still working to cool you off, it must also work harder and faster to get that smaller amount of blood to your working muscles. That’s why it’s always important to replenish the fluids you lose by drinking plenty of water while you exercise.

Learn the warning signs

Recognize the signs of heat stress and take immediate action. Headache, fatigue, profuse sweating, muscle spasms or cramps, cold and clammy skin and swollen ankles and feet can mean you’re getting too hot. Move to a cool or air-conditioned area, drink fluids, shower in cool water and lie down.

Seek emergency medical help if symptoms don’t improve or if they progress to include nausea, dizziness, confusion, rapid pulse, high fever, fainting or warm, dry skin with no sweating.

Prevention is key

Pay attention to weather reports. Heat disorders can occur any time the temperature and humidity both rise above 70F and 70 percent respectively, or the heat index is greater than 80F. Drink plenty of fluids, avoid caffeine and alcohol (they’re dehydrating), limit activity to a cooler hour and wear light-colored clothing
made of natural fabrics.




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This article is not a substitute for professional medical advice, which should be obtained from your doctor.