Tony is a sled dog, which means he’s a mutt, with a little Siberian husky in the mix, who’s been specially bred for speed, desire, and resilience. When Tony’s in peak condition, his VO2 max a measure of his ability to take in and use oxygen in the bloodstream tops out at more than 200 milliliters of oxygen per kilogram of body weight per minute. (Back when Lance Armstrong was racking up multiple Tour de France wins, his famously high VO2 maxed at around 85.) Tony may be a little flabby now, but in a few months, when he’s competing in the Iditarod, he’ll be able to run an average of 100 miles a day over eight or nine days, working at 50 percent of his VO2 max for hours on end. As part of a team, he can run sub-four-minute miles for 60 or 70 miles.
“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.”
Some might argue the point by bringing up birds that can migrate for thousands of miles. But migratory birds aren’t racing or pulling weight, and, more important, birds don’t make good comparative models for human physiological studies. Tony and his mammalian kennel mates do, and they’re helping scientists answer fundamental questions that could, in the near future, lead to new ways to enhance the performance of two-legged athletes like you and me.
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