What are the greatest animal athletes? Maybe thoroughbred horses, or greyhounds, or the the Puppy Powl pups? All great choices, certainly, but when it comes to strength, stamina and teamwork not much can top the sled dogs of the Iditarod.

According to Brian Alexander at Outside Magazine, these dogs are as good as it gets when it comes to animal athleticism. Alexander describes one dog named Tony:

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.

Ken Hinchcliff, a veterinary physiologist who has studied sled dogs like Tony for years, told Alexander, “There is no other animal, including humans, that comes close to competing." Sled dogs are so good at running and pulling and not getting tired that some people think we might be able to learn something about exercise in humans from them.

As large mammals, we humans share a lot of our genes with dogs, and some exercise physiologists say it’s enough to make dogs worth studying to find human applications. If they could get a human to run for that long, that fast and recover that quickly, they’d quickly have a super soldier on their hands. And DARPA knows that. They sent Joe Bitezki, a DARPA researcher, around to vet schools to get connected with vet students.

But Bitezki tells Alexander that there are indeed some key differences between dogs and humans:

The most important difference between the dogs and people, though, may have to do with energy how sled dogs get it and how they use it. Physiologists refer to energy sources as "substrates," and there are three basic kinds: carbohydrates, fats, and proteins. Fats have big advantages over carbs. First, they contain about twice the caloric density, so a gram of fat can supply a lot more energy than a gram of carbs. Second, they burn "cooler." But human muscle relies primarily on glucose, a carbohydrate that's stored in muscles as glycogen, becoming glucose again when it's used. Glucose burns "hot" compared with fat. "It's like the difference between regular ethyl and nitro fuel in a hemi," Bielitzki says. "You can use nitro once in a while, but you can't go forever without burning out the engine."

So while humans won’t ever be dogs, or burn energy the same way, we might still be able to learn something from the masters of the winter race.