The phrase is used to signify an irreversible, long-term physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes.

After all, it is said, Africans typically run many miles to school and have the advantage of a running-rich, high-altitude environment.

If the animal moves to a high-altitude environment, or dives into the water, there will be a pressure difference between the middle ear and the outside environment.

But what Kenya has are tribal traditions of running prowess and a tolerance for stress, a strengthening, high-altitude environment and an enforced mobility in the young.

But the demands of simultaneously running Base Camp and meeting the medical needs of some twenty-five people in a remote, high-altitude environment proved to be more than she'd bargained for.

The stove can outperform some commercial models in cold or high-altitude environments, where propane and butane canisters might fail.

When I'm in a race," said Drossin, referring to her progress in Alamosa's high-altitude environment, "I notice even the Kenyans breathing harder than I am.

Among animals only few mammals (such as yak, ibex, Tibetan gazelle, vicunas, llamas, mountain goats, etc.) and certain birds are known to be completely adapted to high-altitude environments.

Ethiopian runners are endowed with a fortuitous mix: natural athletic ability, dedicated coaches and a high-altitude environment.

In high-altitude environments, the low temperatures and pressures can sometimes produce natural mummies by a process of freeze-drying.