It's 6:15 A.M. as I approach the home of one of the world's greatest athletes. His name is Tony, and he lives in a tiny plywood shack about 30 miles outside of Fairbanks, Alaska. By all rights, he should be exhausted. He got up at four and ran 22 miles in a mid-September, pre-dawn chill, and he wasn't running on nicely paved roads. He ran across fields and through muddy ruts on dirt trails while he and a few teammates tugged against harnesses attached to an ATV. By any measure, it was an absurdly tough workout, and it was even more remarkable because this was Tony's first hard run in months. So I'm amazed to see him standing outside his door, looking refreshed and eager.
As you may have guessed, 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.
THAT MAY SOUND far-fetched, since dogs and humans are so different, but Mike Davis, an Oklahoma State University veterinarian and exercise physiologist, thinks otherwise. Davis has brought me here, to the home of mushers Aliy Zirkle and Allen Moore, to show me the dogs up close and explain his complicated research. As he and I wade into a pack of 50 yelping, howling animals, he points out that dogs are large mammals, just like people. On the level of genes and regulatory proteins, we're surprisingly close cousins.
"When we figure out how dogs are regulating muscle proteins to accomplish what they do," he tells me, "it is possible we can get human muscle to do the same things."
Davis, 46, has been engaged in a multiyear quest to do just that during which he's gone into debt, mortgaged his house, scraped together government and foundation grants, and endured frozen equipment and logistical nightmares all in an effort to give people the same physical powers that Tony has. Today, he and three colleagues Ray Geor, from Michigan State; Pauline Entin, from Northern Arizona University; and Shannon Pratt, from North Carolina State are here thanks to funding from the Diabetes Action Research and Education Foundation, which wants to know more about how the dogs regulate glucose and insulin, the stuff that powers the bodies of both canine and human athletes. That work is of a piece with broader research that Davis began years ago, when the U.S. military's blue-sky science outfit, the Defense Advanced Research Projects Agency (DARPA), realized that studying sled-dog performance could help them improve the performance of human beings.