Hell-Bent by Benjamin Lorr Read Free Book Online Page A

the form of a heat pack on a tight muscle, this expansion can be wonderful, increasing circulation, allowing deeper flow into the muscle. When applied bodywide however, the sudden increase in the size of the vessels decreases the pressure in the system (think of the difference in pressure between water running through a tiny nozzle or a wide tunnel). The reduction in pressure forces the heart to pump harder to push blood the same distance, further straining the system and reducing blood available to other organs.
    Finally, of course, there is sweat. Lots of it. Pumping fluid to the skin allows evaporation to release unwanted heat. The hotter it gets, the more the body sweats; the more sweat, the more evaporation cools. 4 The flipside to this process is a decrease in blood volume. The sweat sliding down your back is no longer circulating in your body. As the plasma volume decreases, there is a cascading effect, compounding all previous reactions. The heart must work even harder still. The organs receive even less blood. Less bloodflow means less cooling at the skin. Core temperature escalates and the body comes ever closer to shutdown.
    All of which is why exercise in high heat feels harder: The muscles are starved for energy. The brain isn’t receiving enough blood and starts sending freakout feedback messages. The heart physically can’t beat hard enough to pump blood to all the places it is needed. The result is the common demoralizing effect where a relatively easy workout can suddenly feel incapacitating.
    “The brain is especially sensitive to these changes,” Dr. Yeargin explains. “It is a princess. It wants the perfect temperature, perfect electrolyte balance, perfect sugar levels. … If it doesn’t get it, you see confusion, disorientation, irritability, grumpiness.”
    Hallucinations?
    “Hallucinations and fainting and seizures and coma.” When you faint, your body is essentially commanding you to lie down fast. The new orientation makes it easier to get blood to the brain.
    I think of classes where I have been ruthlessly and suddenly dropped to one knee.
    When I tell her about the yoga, she is skeptical. “Most of my work is telling people to avoid exercising in exactly that type of situation. … When I study heat stroke, I put people into a room that is about one hundred four degrees to purposely stress their bodies.
    “That type of situation can be devastating if core temperature rises to a dangerous level. … Rapid deterioration of organs, coma, death.” There is a loss of control as the brain shuts down: internal feedback mechanisms fail, toxic substances flood from the gut, cells starve, a bad situation becomes much worse. Even if a heat stroke victim survives the initial event, there is often long-term damage to the brain, kidneys, and liver.
    Listening to her talk, I can’t help but nod my head in agreement. I wonder how anyone ever manages to make it through class alive, much less return and claim it’s healthy. Not only is it hot, but many studios artificially raise humidity, making it even more miserable and destroying whatever cooling effect comes from sweat. Not only are the exercises intense, but many are designed specifically to cut off and stress blood flow. It’s crazymaking. But what’s especially crazy making is that it feels great. I emerge from class feeling reborn.
    And so somewhat reluctantly, I find myself explaining the benefits to Dr. Yeargin, hoping that I don’t sound like a New Age crank. I tell her about my weight loss. My gains in strength. The feeling that my concentration, clarity, memory, and reaction time have all improved. The extreme energy. The elation that carries throughout my day, lasting beyond any postexercise runner’s high. My voice swells, and I tell her I think it makes me a better person.
    She considers. She is kind. “To be honest, it’s an unstudied area. I’m almost positive there is nothing in the scientific literature on that. … There are