Pulmonary capillary reserve and exercise capacity at high altitude in healthy humans.

Purpose: We determined whether well-acclimatized humans have a reserve to recruit pulmonary capillaries in response to exercise at high altitude.

Methods: At sea level, lung diffusing capacity for carbon monoxide (DLCO), alveolar-capillary membrane conductance (DmCO), and pulmonary capillary blood volume (V c) were measured at rest before maximal oxygen consumption ([Formula: see text]) was determined in seven adults. Then, DLCO, DmCO and V c were measured pre- and post-exhaustive incremental exercise at 5150 m after ~40 days of acclimatization.