When moving on Alaska's trails, fat is good
On packed snow trails around Alaska, athletes are gliding, rolling and striding in preparation for winter races, such as the Susitna 100 and the 350-mile Iditarod Trail Invitational.
Competitors in the races, held along parts of the Iditarod Trail, choose their weapons: racers can bike, ski, run, or snowshoe the courses. During a similar race a few years ago, the now-defunct Iditasport, scientists poked and prodded some competitors in order to learn what it takes physically and mentally to do the race.
Sam Case is a professor of exercise science at Western Maryland College and a veteran of the 100-mile Iditasport who traveled to Fairbanks a few years back to discuss what happens to humans when they choose to exercise in cold weather. Case dashed the myth that anyone who exercises outside in cold places will freeze his or her lungs. Alaska athletes already know this is folklore rather than fact, but Case cited a study in which researchers found that dogs were able to inhale air colder than minus 70 degrees Fahrenheit 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 exercises 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 loved 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 after the 2000 Iditasport. 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, appeared as a typed word 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.
