I have been talking a lot lately about the disorders associated with exposure to constant stress. It is time we add a completely different form of stress to this list of things we must be concerned about — heat stress. As the Centers for Disease Control and Prevention reminds us, exposure to extreme heat can spiral into heat cramps, heat rashes, heatstroke, heat exhaustion and more. The young and the old and especially people with preexisting conditions are susceptible to the damages of excessive hot weather. Exposure can even lead to a preventable death.
Live Science reports that June 2021 was the hottest June in American history and the fourth hottest worldwide, which resulted in melting power cables in Portland and Seattle experiencing its hottest day ever — a scorching 108 degrees Fahrenheit. Canada was not spared either, recording national all-time high temperatures three days in a row, reaching 121 degrees Fahrenheit in British Columbia on June 29.
According to data from the European Union’s Copernicus program, which produced climate measurements from billions of observations taken by satellite, the culprit was a dangerous weather phenomenon called an omega block: a dome of hot air trapped in place by atmospheric currents.
John Eric W. Smith, an associate professor of exercise physiology at Mississippi State University, writes in a recent post on theconversation.com that this heat dome settled over the Pacific Northwest for four days, setting record temperatures, less than a month into North America’s official summer.
In the Southeast and Southwest, which regularly experience high heat stress, most buildings and homes have air conditioning that helps people maintain healthy temperatures. As reported by NPR’s Monica Samayoa, this weather phenomenon has occurred in a region known for temperate summers, where many have never needed air conditioning. They were hit hard. The late June heat wave left hundreds of dead across the Pacific Northwest, British Columbia and Oregon.
“Humans can tolerate most areas of the Earth, but extreme heat requires extra steps,” writes Smith. “As an exercise physiologist, I know that the human body is an amazing machine. But like all machines, it functions effectively and safely only under certain conditions … People frequently debate whether wet heat in places like Florida or dry heat in desert locations like Nevada is worse. The answer is that either setting can be dangerous.”
To combat extreme heat, Smith says we must consider how heat affects the body. “Sweating is your body’s primary way of cooling you off. When sweat evaporates away from your skin, it takes heat with it. But when humidity is high, the air already holds a lot of moisture, so the sweat remains on your skin,” he writes. “As it saturates clothing and drips from the body, it can remove only a small amount of heat compared with the cooling that comes with the evaporation of sweat.” He also points out that bodies that are regularly exposed to heat can acclimatize or adapt and improve their ability to cool. These individuals begin sweating earlier than people who are not acclimatized to heat.
“One of the first things our bodies do in adapting to heat is to produce more plasma — the watery portion of blood. This enables our circulatory systems to move heat to the skin more effectively so that sweating can remove it from the body.
“Behavior changes are another way of adapting to heat stress,” says Smith. “Since midday is typically the hottest part of the day, it makes sense to avoid physical work and exercise then.” Also, taking advantage of shade is another important strategy. “Staying in the shade can significantly reduce the external heat load on people who have to be outdoors during hot spells.”
Carol Ewing Garber, a professor of movement science at Columbia University, and Dr. Matt Leonard, attending emergency physician at Suburban Hospital, Johns Hopkins School of Medicine, are two specialists in heat and exercise who recently discussed on NPR the science behind exercising in the heat.
They both agreed that a person can safely exercise when it is hot but must do so with great care. “That midday sun can add as much as 20 degrees or more to the actual air temperature,” says Garber. “You really have to be careful about that.” They also caution about eating right before. Garber believes an hour between eating and your workout in the heat is needed. “It takes blood and energy to your gut to digest the food and that makes more body heat — not what you want when you’re already hot.” If you had a heavy meal such as a cheeseburger, she suggests waiting two to three hours before outdoor exercise. She also believes you should not eat after a hot run. “Instead, hydrate right away and wait until you’ve cooled off to eat, since digesting food will delay getting your body back to its usual temperature.”
Wear material that will help your body breathe, such as loose fitting, sweat-wicking athletic clothing that allows your skin to perspire and cool. “Avoid materials like cotton that basically keep the heat close to your body,” Leonard advises. Hydrate before, during and after exercise because dehydration can sneak up on you.
Most importantly, know the warning signs of heat exhaustion. They include fatigue, extreme thirst, nausea, headache, shortness of breath, rapid breathing, muscle cramping and a general sense of lightheadedness. These are also the warning signs for heatstroke, which is a much more serious emergency and could include confusion, vomiting, seizures, cardiovascular collapse, or passing out and a lack of sweating.
If you suspect you or someone you are with has heat exhaustion or heatstroke, you should stop what you are doing immediately. If symptoms point to heatstroke — especially anything neurological such as confusion — that individual needs to be taken to an emergency facility immediately, says Leonard. If you do get a heat-related illness, it can last for a few days. So, take care of yourself, and do not rush back out into the sun, advises Garber.