Very interesting.
Sea-level athletes who specialize in short-distance high-power-output race events tend to burn carbohydrates, especially glucose (rather than fat). Since oxygen delivery is a key limiter of short-distance race performance, I guess it makes sense that they favor the mode of metabolism which delivers more energy from less oxygen. A key goal of their long-term training program is to build up carbo-burning mitochondria and enzymes.
My guess is that what's special about many Sherpas is that their body strongly favors carbo-burning even in "long slow distance" performance -- where most sea-level athletes would switch to greater use of fat-burning - (and a long-term training program would try to build up fat-burning enzymes, and _storage_ of fat fuel inside or very close to propulsive muscle cells).
But sea-level athletes who go up to high altitude do not "learn" this carbo-favoring trick for "long slow distance" performance. Instead they just build up more red blood cells (which increases their rate of embolisms / blood clots) - and continue to favor burning fat.
As for "other populations", the article implies the native Tibetans do _not_ have the carbo-burning trick. My memory from other articles is that native Tibetans _do_ have higher Red Blood Cell count, but many of the also have a special blood genetics that somewhat protects them from embolisms / blood clots. Unlike Han Chinese who _move_ to Tibet, who do increase RBC significantly, but continue to lack the special embolism protection.
Ken
Post edited at 05:55
