"When it comes down to sheer capacity for prolonged exercise," says Ken Hinchcliff, an Australian veterinary physiologist who's done more research on sled dogs than any other scientist, "there is no other animal, including humans, that comes close to competing."
Outside's Brian Alexander visits the Fairbanks-area kennel of Aliy Zirkle and Allen Moore -- and focuses on a dog named Tony -- to learn what's known so far about sled dog stamina, and what's not known.
If a man performed anything close to such extreme exercise, he'd have to recruit every drop of blood his body could muster, sending it through the lungs and to the muscles. That blood would be rerouted from other organs, such as the kidneys, the liver and the gut. But that requires those organs to virtually shut down, which you can do for only so long before you start to damage them.
The researchers have also gained some insight into the mysterious dog deaths that seem to plague the Iditarod each year.
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