Doctors Warn: The Worst Time to Exercise Outside in Hot Weather

Hot weather can place significant strain on the body, especially for people who regularly walk, run, exercise, or do physically demanding work outdoors. One of the organs that bears the greatest burden in extreme heat is the heart.

To help cool the body during heat stress, the heart has to beat faster and pump blood more forcefully. At the same time, increased sweating causes fluid loss. Together, these factors can raise the risk of dehydration, heatstroke, and a sudden drop in blood pressure.

Despite these risks, many people still head outside for walks, runs, workouts, or strenuous yard work during the hottest hours of the day. Cardiologists warn that this can be dangerous and, in many cases, easily avoided.

Why Cardiologists Warn Against Midday Exercise

Dr. Arash Bereliani, a preventive cardiology specialist, warned in an interview with Parade: “Please stop doing intense exercise outdoors in the middle of the day, especially between 11:00 a.m. and 4:00 p.m., when the heat is at its peak. So many heat-related emergencies I see could have been prevented simply by moving the workout or yard work to a cooler part of the day.”

According to experts, the combination of high temperatures and high humidity can make it harder for sweat to evaporate efficiently. Because evaporation is one of the body’s primary cooling mechanisms, this makes it more difficult for the body to release excess heat.

Dr. Laxmi Mehta, director of preventive cardiology at The Ohio State University Medical Center, explained: “To keep the body cool, the heart has to work harder in extreme heat, which can lead to a faster heart rate and increased cardiac strain. In addition, sweating in the heat can lead to dehydration, electrolyte loss, and a drop in blood pressure.”

Some People Face an Even Greater Risk

The dangers of exercising in extreme heat can be particularly serious for older adults and people with chronic illnesses, high blood pressure, or respiratory problems.

However, doctors emphasize that young and otherwise healthy people can also be at risk if they overexert themselves in high temperatures. Being physically fit does not make someone immune to dehydration, heat exhaustion, or heatstroke.

Warning signs such as dizziness, nausea, a rapid heartbeat, or suddenly stopping sweating should not be ignored. These symptoms are signs that the activity should be stopped immediately. The person should move to a cooler or shaded area and drink fluids.

Change the Time or Location of Your Workout

Avoiding the hottest part of the day is one of the simplest ways to reduce the risks associated with exercising in extreme heat. Instead of exercising outdoors between 11:00 a.m. and 4:00 p.m., consider moving your workout to a cooler part of the day.

On particularly hot days, experts recommend exercising indoors in an air-conditioned environment instead.

A regular exercise routine is important for overall health, but when temperatures soar, adjusting when and where you exercise can reduce unnecessary strain on the heart and help protect your body from potentially dangerous heat-related illness.