How sled dogs manage to run 1,100 miles in temperatures as low as -40 Celsius F

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Washington, Sept 28 (AN): Racing sled dogs are considered to be the ultra-athlete canine for their ability of covering 1,100 miles from Anchorage to Nome, Alaska, sometimes in just nine days, during the Iditarod Trail Sled Dog Race. Now, a new research sheds light on how they do it.

The study led by Dr. Michael Davis at the Oklahoma State University's Centre for Veterinary Health Sciences has focused how these dogs are capable of running continuously, despite heavy blizzards, temperatures as low as -40 Celsius F, and winds up to 60 mph.

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, including depletion of muscle energy reserves, increases in stress hormones, evidence of cellular injury (such as to proteins, lipids and DNA), and oxidative stress.

However, with subsequent consecutive days of exercise at the same intensity, these changes are reversed. 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.

These dogs also have enormous aerobic capacity.

While the untrained sled dogs have an average aerobic capacity of 175 ml/kg/min VO2 max (ratio of volume of oxygen to body weight per minute), the aerobic capacity of the fully conditioned sled dogs is estimated to be about twice that (300 ml/kg/min).

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 that this process is a desirable trait intended to efficiently support exercise in the racers.

The mechanisms that make these four-legged athletes premiere in performance is still unknown.

Davis theorizes that it may involve the regulation of extremely thin membranes in the muscle fibres and changes in the cells that are responsible for the body's energy production.

"These are one-of-a-kind athletes. What we learn from them will undoubtedly tell us a lot about human performance as well," he said.

The findings will be presented at part of the American Physiological Society's (APS) conference.


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