Fat Loading and the Winter Athlete
A few months ago, I joined about 130 other people in the Iditasport, a race “across 100 miles of frozen Alaska.” Competitors in the race, held along part of the Iditarod trail, were allowed to choose their weapons: racers could bike, ski, run, or snowshoe the course. Along the way, some participants were poked, prodded, and asked personal questions in the name of science.
One of the lead pokers, Sam Case, was in Fairbanks recently to discuss what happens to humans when they choose to exercise in cold weather. Case is a professor of exercise science at Western Maryland College and a veteran of the 100-mile winter race.
Case dashed the myth that anyone who exercises outside in cold places will freeze his or her lungs. Alaska athletes already know this is a bunch of hooey, but Case cited a study in which researchers found that dogs were able to inhale air colder than -70 F with no ill effects. Just like dogs, humans warm air so rapidly in our mouths and noses that cold air does no damage within.
Cold takes its toll in other ways. Muscles become less efficient, giving off more heat then they do in warmer temperatures. An athlete’s oxygen consumption also goes up in the cold as his or her body burns food to release energy. Case said those exercising in Alaska during winter should expect a slight decrease in endurance, a drop in body core temperature, muscles that contract at a slower rate, and a lower heart rate when compared to summer exercise.
Winter activities have a higher energy cost than the same exercise in the summer. Walking on snow takes three times the energy of walking on a treadmill, Case said. Moving on snow takes a lot more food, too. Racers on the 100-mile Alaska course consumed an average of 73 calories per mile. Competitors in two races of the same distance in Hawaii and Australia averaged 17 and 14 calories per mile, respectively.
The Alaska racers love high fat items, such as cheese and peanut butter. About 25 percent of their race snacks were fatty foods.
The virtues of eating fat during cold weather exercise seem to be confirmed in a study researchers performed on racers’ diets and their ability to perform a mental test. In the test, designed by Sherri Hughes of the Western Maryland psychology department and Kristin Stuempfle of Gettysburg College, competitors looked at a sheet of paper with the words “red,” “green,” and “blue” repeated in rows. To test the racers’ mental sharpness, the researchers printed the words in ink of a different color. “Red,” for example, was typed in blue or green ink. Both before the race and after completing the race, racers spoke the color of the ink, rather than the name of the word. After being out on the trail for as long as 24 hours, competitors stumbled through as many words as possible in 45 seconds. Researchers found the racers who ate more fat during the race performed better on the tests than those who ate less.
