Meanwhile, global warming gradually converts the American southwest and midwest into something akin to the Australian Outback. Do these temperatures begin to appear uninhabitable for humans? They do to me, a cool-weather person who suffers during a humid 82 fahrenheit (give me a sunny 52 degree morning any day). Here's a few tips to get help you through the rest of the Summer and beyond.
(1) Acclimate. You can't "beat the heat" as the cliche goes, you can only live better with it. Your body has an amazing ability to adapt or acclimatize to the heat, but you have to help this mechanism along by exposing yourself judiciously to hot temperatures.1 It takes no more than a continuous hour and a half or so per day of walking or light biking in hot weather to cultivate this adaptation (although more intensive exercise seems to quicken the process) – "even resting in the heat results in some acclimation."2
This is why athletes training for a hot Olympics try to simulate the equatorial conditions as much as possible during training.
We know it isn't healthy to live in either winter or summer in completely 24-hour artificial environments, because they shut down these built-in adaptive responses. I do a lot of cold-water swims throughout the year and very-cold weather skis and hikes – and now that I'm better informed about heat adaptation, I'll be adding these behaviors to my repertoire :)
What happens to the body during heat adaptations?
- "The three classical signs of heat acclimation are lower heart rate and core temperature, and higher sweat rate during exercise-heat stress. Skin temperature is lower after heat acclimation than before..." Basal metabolic rate is [also] decreased during warmer months.3 BMR represents the calories you burn just by maintaining your physical systems, such as the heartbeat and the function of the brain.
- "With acclimatization, the sweat glands become able to conserve sodium by secreting sweat with a sodium concentration" lower than non-acclimatized people.4 You sweat more when you're heat adapted, but the sweat contains a lower salt concentration, so it's "more efficient sweating."
- Heat adaptation hones your thirst response, so you don't let yourself become dehydrated. "Therefore, heat acclimated persons will dehydrate less during exercise in the heat, provided that access to fluids is not restricted. This is an important adaptation as heat acclimation increases sweating rate and if fluid replacement is not proportionately increased then greater dehydration will occur."5
- "Most studies report that heat acclimation increases total body water. The magnitude of increase ranges from 2.0 to 3.0 liters or ~ 5% to 7% of total body water."6 This seems to be a significant factor – you can hold on to an extra two to three liters of water just by being better acclimatized.
The body isn't just some dumb machine that constantly needs to be synthetically cooled, baked, and medicated. If you feel like you've got the A/C market cornered between your house, car, and office, then I have one (no...three) words for you: power grid crash. Recall what happened in India lately. And it happens occasionally in the U.S. too albeit, hopefully, at a smaller scale.
A funny and telling story I recall from a long time ago involved a participant in a wild race across the Sahara Desert called the Marathon Des Sables or Marathon Of The Sands. A reporter covering the 150-mile or so six-stage race wrote about a Frenchman in his sixties, a "mystic" who could sit for hours in a tank of ice water.
The reporter found him halfway through the brutal ultramarathon, walking barefoot on blistered feet with his shoes tied together and slung over his shoulder. All the man said was "the desert is my friend." Yeah right, the reporter thought to himself; this guy will never finish the race (I heard that the race had a "two IV" rule – if you had to have a second intravenous fluid replacement, they pulled you from competition!).
Later, the reporter spotted the man among a group of finishers several miles away; he'd not only finished, but he was sitting placidly in the lotus position, "chilling out" as it were. What did this Zen guy know that we don't know? Acclimate, adapt; acclimate, adapt.
(3) Avoid pavement and heat islands. Paved-over areas will amplify heat by as much as 10 degrees or more. Park your car under trees and stay in forested areas as much as possible. Obviously, never leave a child or a dog in a hot parked car! Similiarly, don't linger all day inside among laptops, computers, flatscreen TVs, and other electronics, as they generate a lot of heat and will significantly heat up a room. Just unplug 'em to cool off, and disconnect.
(4) Enjoy cold water swims and cold showers – they have benefits that extend beyond relief from the heat.
(5) Drink more water, within reason, and monitor the color of your pee (if it's clear you're well hydrated; very yellow you're dehydrated).
(6)Take it down a notch physically if you're a regular outdoor exerciser. The exception is training for a hot-weather event, but take it slow nonetheless as heat-adaptation takes up to two weeks (a study discussed in the cited article here indicated adaptation after 10 days when the heat exposure was daily, and 27 days when the subjects were exposed every third day).
(7) Eat lighter, colder foods in the heat and drink cold not hot tea or coffee so as to not ramp up your own thermogenesis or heat production.
(8) Dress lighter, looser, and in white, reflective colors, and expose more of your skin to any breezy conditions, to help increase evaporative cooling (taller people can dissipate more heat because they have more exposed surface area, thus early people in Africa were tall and lithe, while the Paleolithic peoples like Neanderthal were short and broad because they lived in a much cooler environment). Obviously, don't expose skin to the sun to the extent of sunburn.
(9) If you can find a cool spot, sleep and siesta during the hottest periods of the day, around 11am to 2pm, and "live at night" or work during the earliest cooler hours.
(10) If you have the opportunity, go to high elevations, where the temperature is likely to decline about 5 degrees per thousand feet. In my experience, this figure can wildly fluctuate depending on local conditions – yet you can almost guarantee that it will be appreciably cooler and breezier in the high country compared with the "heat islands" created in the vast developed flatlands. A place in VT I stay in, at 1,500 feet above sea level, is almost always about 8 degrees cooler than where I live at 50 feet above sea level.
1 Human Adaptations to Heat and Cold Stress, Michael N. Sawka, Ph.D., etal.; http://ftp.rta.nato.int/public//PubFullText/RTO/MP/RTO-MP-076///MP-076-$KN4.pdf