THE PILL IS SMALL, PURPLE, CYLINDRICAL—ABOUT THE SIZE AND OMINOUSNESS OF A .38-CALIBER BULLET. I haven't known Robert Kenefick ten minutes when he hands me a rubber glove and tells me where I can stick it. Without wallowing in too much detail, let's just say the pill—which is really a wireless temperature sensor—isn't going in the easy way.
Kenefick is 45, bespectacled, with the ironed-khakis-and-Rockports appearance of the college professor he once was. He's not without sympathy. "I know most people want dinner and dancing before they do something like this," he jokes as he leads me to the restroom. Suddenly, I'm keenly aware of how bland my social life is.
Mission accomplished, I waddle back to the testing area. "Let's do it," says Kenefick. He opens a ponderous steel door, and we step into a metal-walled room that's precisely the suffocating temperature of a Tucson afternoon.
"Unnggh," I groan.
Kenefick is apologetic. Today the room is "only" 40 degrees Celsius—104 degrees Fahrenheit. The first time he ran this test, he says, "we had guys at 50 C," or 122 F. Somehow I don't feel shortchanged. The room's steel walls are hot. The steel floor is hot. Pumps roar as they exhale air that feels like a Bikram yoga lover's dream. Inside, I'll bake for the next three hours to get thoroughly dehydrated before I mount a stationary bike and pedal maniacally. The goal: to gauge just how much my performance craters when I'm hotter and thirstier than I've ever been.
KENEFICK IS A PHYSIOLOGIST at the U.S. Army Research Institute of Environmental Medicine (USARIEM)—a vanilla-sounding name for a cluster of gee-whiz laboratories, little known even inside the military, whose mission is to build soldiers capable of enduring anything Mother Nature throws their way. Though primarily a defense project, the institute's work also trickles down to civilian life, affecting how the rest of us run, drink, eat, exercise, and survive in the outdoors.
Kenefick specializes in heat problems. Army brass call when they want to know whether slathering on the insect repellent deet makes it harder for soldiers to sweat and cool off. (Nope.) Or when they want to learn how to make soldiers acclimate faster in sweltering conditions. (He's working on it.)
Just now I'm duplicating a recent experiment that was aimed at answering a crucial question among thermal researchers: Why do we bonk when the going gets hot? A standard hypothesis, Kenefick explained earlier, is that failure is wired into our brains. "You have a set point in your hypothalamus," he says, referring to the portion of our gray matter that, among other jobs, regulates body temperature. "When you get too hot, your brain says, 'You're way too hot!' and tells your body to slow down." Lab studies done elsewhere suggest that a body temperature of 104 degrees Fahrenheit is the crisis point at which the mind begs for mercy.
