Elite athletes in many sports use the “rest high, train low” strategy to improve endurance. But can it help dogs?
“That’s the million-dollar question,” said Jeff King, a four-time champion of the Iditarod Trail Sled Dog Race, who is testing the technique with his Alaskan huskies during this year’s race.
In humans, sleeping in tents or chambers that simulate oxygen deprivation — called hypoxic devices — increases the production of oxygen-carrying red blood cells. That is thought to improve endurance.
Some top mushers live at altitude, but King’s calculated attempt may be groundbreaking, even if it is not clear if the same principles apply to sled dogs.
“To the best of my knowledge, nobody has ever tried this before,” said Michael S. Davis, an associate professor in the department of physiological sciences at Oklahoma State University’s Center for Veterinary Health Sciences. He is a leading researcher in how animals adapt to strenuous exercise.
King has been an innovator in sled-dog racing. He trains his dogs in water during the summer and has developed sled and harness designs that have been copied by his peers. He spent about $50,000 last year converting a barn on his property in Denali, Alaska, into a chamber in which the oxygen content of the air is about the same as it is at 9,000 feet.
In October, King used two control groups of 12 dogs each to monitor changes in their physiology. One group slept in the high-altitude chamber; the other did not. Diet and training were kept the same for all the dogs.
Beginning in November, 30 of King’s best dogs slept in the hypoxic conditions at night and trained at lower elevations during the day.
According to Arleigh Reynolds, a veterinarian and a canine exercise physiologist, who was working with King, the percentage of red-blood-cell mass increased in the dogs who slept in the chamber, although it leveled off quickly once the dogs returned to normal sleeping conditions.
More significant, he said, was that the dogs’ ability to remove lactic acid, a byproduct of strenuous exercise, improved by 60 percent initially and by 30 percent two weeks later.
Reynolds said that this meant King’s dogs were using their limited stores of carbohydrates more efficiently.
“That’s huge,” said Reynolds, who teaches at the University of Alaska Fairbanks and plans to publish a paper on his research.
But it is debatable whether canines would benefit in the Iditarod, the annual 1,100-mile race from Anchorage to Nome, which traverses frozen rivers, mountain ranges and wind-swept tundra.
The 51-year-old King, who won the Iditarod last year and three times in the 1990s, was in fifth place yesterday with about 200 miles to go. The race leader, Lance Mackey, had about 170 miles left. The winner is expected in Nome as early as today.
Davis, of Oklahoma State, said it would be hard to pinpoint the effect of the hypoxic conditions merely by looking at King’s race results. He said that it was unlikely the dogs running the Iditarod would benefit, because they are typically working at only about 40 percent to 50 percent of their aerobic capacity.
Marathon runners, by contrast, would be at about 80 percent of their capacity.
“We don’t know for certain, but my guess would be there is not a significant benefit in this type of event,” Davis said. “I would expect there would be a benefit in a much shorter event, of 20 to 25 miles.”
But, he said, because sled dogs tend to lose red blood cells during long races, “starting with a few more would translate to an advantage closer to the end.”
Another four-time Iditarod champion, Doug Swingley, who lives and trains year-round in Lincoln, Mont., at an altitude of about 6,000 feet, called King’s effort “a waste of time and money.”
Mitch Seavey, the 2004 Iditarod champion, said that there were too many other important factors in the race to make what King was doing much of an advantage.
King said he did not care if competitors dismissed his experiment.
“I’d like to think that I have a little history of coming up with good ideas, not just crazy ideas,” he said last week. “I’m first to tell you that, alone, it’s not going to make the difference. But if my team and one other team of equal ability get on the other side of the range, it might very well make the difference.”