BUILT FOR ENDURANCE

The top dog sled teams that run in the 1000 mile Iditarod race through all kinds of weather and field conditions average about 125 miles a day for a little more...
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The top dog sled teams that run in the 1000 mile Iditarod race through all kinds of weather and field conditions average about 125 miles a day for a little more than 8 days. That is the equivalent of running 38 marathons while pulling a sled with a person on board. How can they do it? Marathon athletes consume on average about 3,000 to 4,000 calories a day, much of which is stored as fat which they burn off during exercise. Sled dogs appear to have a metabolic switch that allows them to largely skip the fat reserve stage, taking up the fat directly from the food they consume and passing it through the blood system directly to muscle cells. This approach coupled with their ability to consume about 12,000 calories a day even though they weigh only about half that of humans is a major part of the answer. That many calories being burned per day translates into an enormous amount of heat. Unlike ourselves, dogs pant, flushing out the air in their lungs about 300 to 400 times a minute. Their long blood gorged tongues serve as an additional source of heat exchange.
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