The essay "Can Your Brain Fight Fatigue?" by Gretchen Reynolds, which appeared in the New York Times on July 15, 2009, explains why some researchers now believe "that exhaustion isn’t just in the muscles but also involves the brain. 'What we now think is that the muscle isn’t acting on its own,' [researcher Ross Tucker] says. 'There’s an interplay of central processing and muscular exertion'.”
KEY CONCEPTS:
"Recently, researchers in England discovered that simply rinsing your mouth with a sports drink may fight fatigue."
"By the end of the time trials, the cyclists who had rinsed with the carbohydrate drinks — and spit them out — finished significantly faster than the water group. Their heart rates and power output were also higher. But when rating the difficulty of the ride, on a numerical scale, their feelings about the effort involved matched those for the water group."
"In a separate portion of the experiment, the scientists, using a functional M.R.I., found that areas within the brain that are associated with reward, motivation and emotion were activated when subjects swished a carbohydrate drink."
"The role of the brain in determining how far and hard we can exercise — its role, in other words, in fatigue — is contentious. Until recently, most researchers would have said that the brain played little role in determining how hard we can exercise."
"Instead, [Ross Tucker, a researcher with the Sports Science Institute of South Africa] and many (but not all) physiologists now believe that exhaustion isn’t just in the muscles but also involves the brain. “What we now think is that the muscle isn’t acting on its own,” he says. “There’s an interplay of central processing and muscular exertion.”
"In other words, the mind, recognizing that the body may be going too hard, starts sending fewer of the messages that tell the muscles to contract. The muscles contract less frequently and more feebly. In a sensation familiar to anyone who exercises, your legs die beneath you."
"I think the training effect of this theory is potentially very profound,” Tucker says. “Training is no longer simply an act of getting the muscles used to lactate or teaching the lungs how to breathe harder.” It’s also about getting your brain to accept new limits by pushing yourself, safely. “Once your brain recognizes that you’re not going to damage yourself,” Foster says, “it’ll be happy to let you go.”
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To read the entire essay and thereby judge the value of the reported experiments used to support the essay's key ideas, click on this link.
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