Think your marathon-running cousin is super impressive? Well, he is. But those 26.2 miles are nothing compared to the more than 1,000 miles that the competitors of the Iditarod traverse. There's no doubt that races like that one, an annual sled-dog race in Alaska, are grueling feats, but you may not fully realize just how able the furry competitors are. Sled dogs like Alaskan and Siberian huskies can handle long endurance races with no problem. The dogs have an impressive VO2max, which basically refers to the amount of oxygen their bodies can take in per kilogram of weight, or their cardiorespiratory fitness level. In the sled dogs, the VO2max is 230 mL per kg. For human marathon runners, it's 85 mL per kg.
The cardiorespiratory fitness level of a sled dog is three times that of a marathon runner.
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Key Facts In This Video
The majority of racing sled dogs are Siberian or Alaskan huskies. 02:40
Humans use glycogen and oxygen to create energy, whereas sled dogs use fat and oxygen. 03:10