Heat waves are undulating across swaths of the U.S. and around the world, causing record-breaking temperatures and thousands of deaths. Scientists predict that climate change will only make these waves more frequent and dangerous, particularly in regions where cooling infrastructure like air conditioning isn’t widespread.
Well, luckily (or unluckily), there is a contingent of biohackers who have a solution that doesn’t involve addressing the ongoing climate crisis. Their approach lies in raising our own tolerance to heat. Or, to poorly paraphrase Shakespeare: What if the fault were not in the sun, but in ourselves?
Samuel Sanchez, a personal trainer and proponent of biological optimization, told The Daily Beast that he uses a number of methods to increase his and his clients’ heat tolerance. That includes exercising in bulky sweaters; spending time in infrared saunas; holding gel ice packs; and taking supplements of L-citrulline, an amino acid, to increase blood flow.
“There’s not too much of a distinction between athletic performance and day-to-day activity,” Sanchez said. “Pushing that ceiling a little bit further can help absolutely anyone.”
Other biohackers promote taking frigid showers, reducing exposure to electromagnetic fields, consuming spicy foods and hot drinks, and ingesting capsules of colostrum, which is the first stage of breastmilk.
However, the body of research on heat acclimatization suggests that only a fraction of these techniques can increase heat tolerance, and experts say there are a number of caveats and safety precautions that at-home biohackers might not be taking into account.
“There’s a limit to how much you can adapt to just by changing your physiology,” said Patrick Fink, a wilderness medicine physician who studies health conditions related to environmental exposures, including hypothermia and heat stress. Fink told The Daily Beast that elite athletes often employ heat acclimatization practices, but even they cannot prepare their bodies for extra-hot competitions like the Badwater 135 ultramarathon—where participants run in reflective blankets and douse themselves in water to cool down.
“There’s not too much of a distinction between athletic performance and day-to-day activity. Pushing that ceiling a little bit further can help absolutely anyone.”
— Samuel Sanchez
“I don’t think you could actually achieve a physiologic adaptation such that you could go out there in a shirt and shorts and just run it and be happy, healthy, or safe,” he said.
Heat acclimatization is based on the general principle that people who are repeatedly exposed to hot environments (simulated or otherwise) become better adapted to their climate. Fink said that comparative studies have found that heat-acclimated people sweat larger volumes of liquid and make more blood than people not used to the heat. The upshot of acclimatization is that it will take a person longer to experience the symptoms of heat stress, like fast heart rate, panting, and exhaustion. And at the extreme end, it could save their life, since unchecked heat stress can lead to heatstroke and death.
Andrew Garrett, an exercise and environmental physiologist at the University of Hull in the U.K., told The Daily Beast that his research looks into heat acclimatization “not by taking pills or placing magical chips in the human body,” but through repeated stints in saunas and hot tubs. Acclimatization protocols depend on the heat source used and whether exposure occurs alongside physical activity or not, but they typically involve daily heat exposures for anywhere from 15 minutes to a few hours, lasting several days to two weeks. After that, according to Fink, the degree of benefit seems to plateau, and some tolerance metrics can even worsen.
Existing protocols may not suit the general population, Fink said, adding that sauna regimens are “intense.”
“Forty minutes in an 180-degree sauna is no joke, and it’s probably not safe for a lot of people,” he said.
Garrett has also looked into supplementing heat exposure with controlled dehydration to speed up acclimatization time. The body of research has thus far been mixed, perhaps dependent on the slightly different methods used. But outside of a research context, intentional dehydration is “actually quite dangerous in the hands of people who really don’t fully understand what they’re doing,” he said.
According to Garrett, one of the limitations of research on active heat acclimatization is that it has mainly focused on pro athletes and soldiers. But imagine if a week before a heat wave, meteorologists’ predictions might set off mass sprints to the sauna?
Garrett has recently turned his attention to populations vulnerable to heat stress—including children, the elderly, and people with underlying cardiac conditions. He said that passive hot water immersion (otherwise known as sitting in a hot tub) “has potential” to be a widely applicable solution, but more work on its safety and effectiveness must be done.
“In a perfect world, it’d be great to have people who are vulnerable be able to go into clinics, where they’d have a hot water room,” because self-regulation leads to problems, he said. Garrett cautioned not to turn a tub’s tap to its hottest, as scalding water can cause burns and will not increase one’s heat tolerance.
Other “hacks,” like cool packs and supplements, are at best benign bunk, and at worst a risky gamble with human physiology, according to Fink and Garrett. Cold packs might make the heat feel more bearable psychologically, but a person who needs to cool down quickly is better off jumping into an ice bath or tepid water, Fink said. He added that cool packs are not a very efficient way to cool the body but would be more efficiently placed near big blood vessels under the armpits, around the neck, or near the groin.
“In a perfect world, it’d be great to have people who are vulnerable be able to go into clinics.”
— Andrew Garrett, University of Hull
Dilating one’s veins with a supplement might theoretically increase heat tolerance, but messing with the body’s natural mechanisms of cooling has the potential to suppress the warning signs of heat stress, Fink said. If it were as simple as popping a pill, all patients would be prescribed it, Garrett said.
And finally, do researchers really need to tell you that rubbing your entire body with capsaicin— the chemical that causes spicy food to burn—isn’t a good idea?
“Will you achieve results?” said Fink. “Probably not—at least not the result you were hoping for.”