Washington, September 25 (IANS) Racing sled dogs stand out for their unparalled athletic ability and prowess - the only one among the hundreds of breeds of ‘man’s best friend.’Every March, during the Iditarod Trail Sled Dog Race, the world’s toughest sled race, they are premier ultra-endurance competitors, covering nearly 1,800 km from Anchorage to Nome, Alaska, sometimes in just nine days.

It is unclear how they can keep running, despite heavy blizzards, temperatures as low as minus 40 degrees Fareinheit, and winds up to 100 kmph. No other animal has been found to come close to the physiological attributes these dogs display, according to an American Physiological Society press release.

Michael Davis, professor at the Oklahoma State University’s Centre for Veterinary Health Sciences, has focused on the mysteries of this breed for work for more than a decade, coming up with interesting results.

The most striking feature of these canines is their ability to rapidly adapt to sustained strenuous exercise in 24-48 hours. Conditioned dogs display most of the metabolic changes that are found in human endurance athletes during their first day of exercise.

During periods of racing, sled dogs can burn up to 12,000 calories daily. A 25-kg dog will consume the equivalent of 24 McDonald’s Big Macs to fuel their run on any given day.

Some of the running dog’s high-fat diet is converted to energy in the liver, and used as fuel in the initial stages of exercise. Preliminary data suggests this process is a desirable trait intended to efficiently support exercise in the racers.

It is worth noting that humans would need 72 Big Macs to fuel the power they need to make a day’s run, assuming their body could absorb and process all the fat contained in the beef.

Within four days after exercise begins, the metabolic profile of the dogs returns to where it was before the race began, despite their sustained, strenuous exercise. When human ultra-athletes become fatigued, they stay that way until a period of recovery that may take a full day.

Racing sled dogs have enormous aerobic capacity. This capacity of the fully conditioned sled dogs is estimated to be about twice that of their untrained counterparts.

These findings will be presented at the ongoing American Physiological Society conference.