"The groundwork of all happiness is health." - Leigh Hunt

Are a few of us naturally higher at it?`

July 21, 2023 – Richard Carter had spent the morning walking the picket line with other striking actors outside Walt Disney Studios in Burbank, California. Now, at noon, the temperature had reached 93°F and a hot breeze was blowing. But Carter, a 50-something supporting actor who plays the tv series that is us amongst his credits, was still cheerful.

Some would call him an “iguana,” considered one of those individuals who, like reptiles preferring to lie at 35 degrees, don't complain when the temperature soars. He notices it, but doesn't give in to it.

“I say, 'Damn, that's hot,'” he said, quickly adding, “I'd rather say that than 'Damn, that's cold.'”

A newcomer from Chicago, he can still vividly describe that day way back when it was minus 20 degrees — and the wind chill felt like minus 60 — while he was waiting for a bus that was 20 minutes late. That's when he and his wife decided to pack up and head west. “Today wasn't so bad,” he said of the 90-degree heat.

Temperatures in Bend, Oregon, are also nice, reaching as much as 35 degrees. But the weather doesn't stop Patrick Fink, MD, 35, an emergency physician and wilderness medicine specialist at St. Charles Health System, from recurrently spending just a few hours on his mountain bike. “I don't mind it, and I have no problem exercising on it,” he says. “I think it's a matter of endurance.”

This summer has been hot, and most of us have hardly missed it. On July 20, greater than 100 million Americans were under Heat warnings, in line with the National Integrated Heat Health Information System, a collaboration of federal partners to supply information on the risks of maximum heat. Cities which can be normally hot, like Phoenix, are setting records this summer: On July 20, temperatures reached 110 degrees Fahrenheit for 21 consecutive days. The world's hottest week on record ended on July 10, in line with the World Meteorological Union. And there will probably be more heat – far more – experts warn.

With extreme heat forecast, with the ability to deal with the warmth is a vital skill. “I think we all have to learn to live with it,” Fink said, “because that's not going to change anytime soon.”

But is coping with heat a matter of ability or is it genetic? Can some people simply handle scorching temperatures while others can't? This is a matter of debate amongst experts, with some saying that individuals are likely to tolerate heat higher or worse.

Genetics or not?

Heat tolerance might be partly genetic, said Dr. Thomas E. Bernard, a professor of public health on the University of South Florida in Tampa who studies occupational medicine and warmth stress. Just as some people have higher natural athletic ability than others, a few of us are higher physically able to face up to high temperatures, he said. But just as sports training may help athletes of all levels perform higher of their sports, improved aerobic fitness may help improve heat tolerance, he said.

Here's why. “Heat stress is not so much about a hot environment, but rather that you are generating heat in your body,” Bernard said, and to ensure that you to chill down, that heat needs to flee. Someone who's aerobically fit also has good cardiovascular capability and is healthier capable of release that heat into the environment, he said.

Genetic aspects probably don't play a giant role in heat tolerance, says Graham M. Brant-Zawadzki, M.D., assistant professor of emergency medicine and wilderness medicine specialist on the University of Utah Hospitals and Clinics in Salt Lake City. Many other aspects influence heat tolerance, he says.

Being chubby or obese, with the additional layer of insulation, could make people less tolerant of warmth. Diabetes can damage blood vessels and nerves and affect sweat glands and the body's ability to chill itself. Certain medications, including blood pressure medications resembling diuretics, antihistamines and psychiatric drugs, can affect heat tolerance. Age plays a task in heat tolerance, with infants, young children and older adults more prone to struggle with heat, Brant-Zawadzki said.

However, he said, “We all have the ability to become more heat tolerant compared to our own baseline levels.”

How to coach and adapt

Regular exercise in the warmth will be the important thing to endurance, said Fink, the mountain biker. “I think I'm used to the heat because I do it regularly,” he said.

Exercising in the warmth builds tolerance, Brant-Zawadzki agreed. “Proceed with caution and with your doctor's approval,” he said.

“The idea is to exert yourself for about 20 minutes at a time and then give yourself 10 minutes to cool down.”

Do that just a few times a day. This, he said, triggers a response on the cellular level, with the body producing more of what experts call “heat shock” proteins. “The production of these proteins contributes to some changes that help people cope better with the heat,” Brant-Zawadzki said.

For example, individuals with higher levels of those proteins hyperventilate less, he said.

The CDC and the National Institute for Occupational Safety and Health define heat acclimation as “the improvement of heat tolerance that results from a gradual increase in the intensity or duration of work performed in a hot environment.” For employers who need to protect their employees from heat-related illness, the authorities offer a Time schedule. The staff steadily increase their working hours in the warmth as much as 100%.

“The heat exposure and physical exertion must occur simultaneously,” Bernard said. When you acclimatize, “you start sweating sooner, sweat more and lose less salt.”

Simple strategy: turn down the air-con

“One thing we will [also] “All we can do is reduce the air conditioning output,” says Brant-Zawadzki. “That limits our ability to adapt to the heat.” It is normal for people to go from a very popular 40 degrees outside to a restaurant where it could actually be as cold as 18 degrees, he says. That doesn't help to extend heat tolerance.

As a general goal, he suggests setting the air-con in your private home or office not more than 10 degrees cooler than it's outside. Of course, if it's 100 degrees outside, setting the air conditioner to 90 degrees won't help. But try to not set the air conditioner 20 or 30 degrees colder than it's outside, he said.

What about dietary supplements?

Researchers are studying the role of the dietary complement betaine, also called trimethylglycine, in improving heat tolerance. So far, it seems to assist in animal studies, said Brandon Willingham, PhD, a registered dietitian and assistant professor of kinesiology at Coastal Carolina University in Conway, S.C., who conducted the research while studying at Florida State University. It may go in an identical approach to the warmth shock proteins, he said.

However, there isn't a evidence yet that it really works in humans, although research is ongoing. “Maybe in a year we can tell a different story,” he said.

Strategies for real life

Conner Ohlau, 41, of Scottsdale, Arizona, works as a project manager for a construction company. “I'm a project manager who works with my hands,” he says, preferring working outside to days at a desk and computer. Recently, he worked outside from 10 a.m. to five p.m. in temperatures as high as 120 degrees Fahrenheit. He says people often can't imagine he works in that intense heat day after day.

He has learned to deal with the warmth. “I stay out of the sun, that's key,” he said, wearing a hat and neck warmer when the sun is intense. “When you're outside, you have to be able to put something cool on your neck every 15 to 20 minutes.” He also changes his shirt often and drinks several liters of water on the most popular days. During the work week, he avoids alcohol, which will be dehydrating.