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EMBARGOED
UNTIL 12:01 AM EST
Thursday,
September 25, 2008
Contact: Donna Krupa
Office: (301) 634-7209
Newsroom Phone: 843-681-0794 or 95
Cell: 703-967-2751
dkrupa@the-aps.org
Lessons From The Iditarod:
How
sled dogs run 1,100 miles through the harshest conditions
 HILTON
HEAD, SC—Dogs are often called “man’s best friend,” and rightly so.
Consider, for example, that they never interrupt us when we talk, are always
happy to see us when we arrive home, and provide comfort when we are
lovesick. Since dogs became domesticated 15,000 years ago, they have worked
with and lived next to humans, which some say may account for the special
bond. Each of the 400 breeds and varieties are unique, but only one stands
out as the ultra-athlete canine: the racing sled dogs.
Racing sled dogs are best known for their “mushing”
each March during the Iditarod Trail Sled Dog Race, the world’s longest sled
race. They are the premier ultra-endurance competitors, covering 1,100 miles
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
–40°F, and winds up to 60 mph. No other animal has been found to come close
to the physiological attributes these dogs display.
Dr. Michael Davis has focused on the mysteries of this
breed for work for more than a decade. The professor at the Oklahoma State
University’s Center for Veterinary Health Sciences will discuss his recent
findings entitled, “Metabolic Strategies for Sustained Endurance Exercise:
Lessons from the Iditarod.” His presentation is part of the American
Physiological Society’s (APS) (www.The-APS.org)
conference, The Integrative Biology of Exercise V, being held
September 24-27, 2008 in Hilton Head, SC.
“Watch the researcher
discuss his work.”
How Do They Do It? The
Exercise Physiology of Sled Dogs
The physiological understandings that Davis and his
colleagues have uncovered thus far are extensive. Among their findings is:
Rapid Adaptation to
Exercise and Endurance—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.
Enormous Aerobic
Capacity—Racing sled dogs 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).
Using A High-Fat Diet
to Fuel Exercise—During periods of racing, sled dogs can burn up to
12,000 kilocalories per day (kcal/day). This means that a 55-pound sled 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 that 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.
Next Steps
The mechanisms that make these four-legged athletes
premiere in performance is still unknown. Dr. Davis theorizes that it may
involve the regulation of extremely thin membranes in the muscle fibers 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.”
******
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS;
www.The-APS.org/press) has been an integral
part of this discovery process since it was established in 1887.
# # #
NOTE TO EDITORS: The
APS Conference, The Integrative Biology of Exercise V, is being held
September 24-27, 2008 in Hilton Head, SC. Members of the media are invited
to attend. To register, or to schedule an interview with Dr. Davis,
please contact Donna Krupa at 301.634.7209 (office), 703.967.2751 (cell) or
DKrupa@the-APS.org. There will be an APS newsroom onsite.
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