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There Are No Shortcuts to Feeling Good at Altitude | Outside Online

For example, if you head from sea level to 7,200 feet, the oxygen saturation of your blood will drop from somewhere in the upper 90s to about 94 percent. That means only 94 percent of the hemoglobin in your arteries is carrying a full load of oxygen. If you then start exercising at a moderate intensity, that number will drop to 89 percent—the equivalent being at 9,800 feet instead of 7,200 feet for the duration of the exercise. So in each of the four groups, half of the subjects were assigned to spend three or four hours a day hiking during the two-day staging period, for an extra altitude boost. The result of all these machinations? A big fat nothing. All eight of the subgroups produced essentially identical results in the final testing at 14,000 feet.