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Deacclimatization - how long does acclimatization typically last
Q. I'm planning on climbing Mt. Hood (11,239 ft) and Mt. Rainier (14,411 ft) this spring; how long does acclimatization typically last? Any advice? Should I try to do Mt. Adams (12,276 ft) the week before?
A. A lot has been written about the effects of altitude on climbers and skiers, and even more on the importance of an appropriate rate of ascent (roughly 1,000 ft/day for heights over 10,000 ft) for proper acclimatization. But not as much attention has been given to deacclimatization, especially as it relates to doing other high-altitude peaks in fairly quick succession.
According to Lawrence Armstrong, PhD, in his book, Performing in Extreme Environments (1), the rate of disappearance of the body’s adaptations to high altitude varies widely from person to person; just as it’s difficult to tell who exactly will experience signs of altitude illness, it’s hard to know how long your acclimatized state will last once you descend from high altitude. If you spend less than a day or two at altitude (say, on a moderate climb of a peak like Baker or Rainier, where most people return to sea level within 24 hours of reaching the summit), your body will not have had enough time to permanently adapt to the altitude. The composition of the blood changes after about 2 weeks of altitude exposure by producing more red blood cells and hemoglobin (the iron-protein compound that transports oxygen) (3) but most people climbing peaks in the Pacific Northwest are only exposed to elevation for about 3-4 days at a time.
Training acclimatization time needs to be longer as the altitude becomes higher. Training for 14 days at or above 6,500 feet (as at the U.S. Olympic Training Center in Colorado Springs) and 28 days at or above 8,000 feet are currently the best recommendations for athletes wishing to compete at similar elevations, while complete adaptation to the extreme altitude of 13,000 feet is possible after a continuous stay for 14 months (3). Obviously, climbers have a tiny fraction of this time open to them.
It’s generally recommended that you try to climb a peak like Mt. Baker (10,778 ft) or Mt. Adams prior to your ascent of Mt. Rainier (or other high peak) in order to 1) see how you feel at higher elevation; 2) get you used to the decreased atmospheric pressure and determine what sorts of foods work best for you when you’re feeling slightly nauseated; 3) get you used to carrying similar weight and using the appropriate gear you’ll be using on your climb; and 4) team building with your climbing group, if possible. However, if your plan is to “acclimatize” using one of the other peaks, try to plan your trip as close to your climb up Rainier as possible, or what little acclimatization effects you will have experienced on Baker or Adams will have already disappeared.
One study cited by Armstrong indicates that the red blood cell volume of high-altitude natives (people who spend most of their lives above 7000 ft) decreases as quickly as ten days after spending time at sea level. Someone spending several hours to perhaps a day or two at altitude simply won’t have enough time for any long-lasting physiological changes. Those who choose to trek in Nepal, however, or participate in an expedition-type climb of a peak over 15,000 ft will have to spend a substantial amount of time adapting to the altitude in order to prevent altitude sickness. This is why climbers who gradually ascend their first peak in Alaska, Bolivia, Chile, or the Himalayas in order to get properly acclimatized can then speed up subsequent peaks, because the body’s ability to perform physical work at high altitude can persist for a few weeks (2). Through personal discussion with our African guide, cook, and porters on Mt. Kilimanjaro, and in talking with local Northwest guides and rangers who spend a lot of time on the mountains, we learned that they typically spend a week in the mountains above 10,000 ft and a week back home; their acclimatization and improved cardiovascular function may persist for several months after returning from altitude, and allows them to make subsequent trips quite easily without needing extra time to adapt.
1: Armstrong, Lawrence E. 2000. Performing in Extreme Environments. Human Kinetics: U.Connecticut, pp. 183-195.
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