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 minus 70 Fahrenheit with no ill effects. Just like dogs, humans warm air so rapidly in their 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.