title: Pulmonary circulation and gas exchange at exercise in Sherpas at high altitude.
abstract: Tibetans have been reported to present with a unique phenotypic adaptation to high altitude characterized by higher resting ventilation and arterial oxygen saturation, no excessive polycythemia, and lower pulmonary arterial pressures (Ppa) compared with other high-altitude populations. How this affects exercise capacity is not exactly known. We measured aerobic exercise capacity during an incremental cardiopulmonary exercise test, lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) at rest, and mean Ppa (mPpa) and cardiac output by echocardiography at rest and at exercise in 13 Sherpas and in 13 acclimatized lowlander controls at the altitude of 5,050 m in Nepal. In Sherpas vs. lowlanders, arterial oxygen saturation was 86 ± 1 vs. 83 ± 2% (mean ± SE; P = nonsignificant), mPpa at rest 19 ± 1 vs. 23 ± 1 mmHg (P < 0.05), DL(CO) corrected for hemoglobin 61 ± 4 vs. 37 ± 2 ml · min(-1) · mmHg(-1) (P < 0.001), DL(NO) 226 ± 18 vs. 153 ± 9 ml · min(-1) · mmHg(-1) (P < 0.001), maximum oxygen uptake 32 ± 3 vs. 28 ± 1 ml · kg(-1) · min(-1) (P = nonsignificant), and ventilatory equivalent for carbon dioxide at anaerobic threshold 40 ± 2 vs. 48 ± 2 (P < 0.001). Maximum oxygen uptake was correlated directly to DL(CO) and inversely to the slope of mPpa-cardiac index relationships in both Sherpas and acclimatized lowlanders. We conclude that Sherpas compared with acclimatized lowlanders have an unremarkable aerobic exercise capacity, but with less pronounced pulmonary hypertension, lower ventilatory responses, and higher lung diffusing capacity.
authors.affiliation: Laboratory of Exercise Physiology, Faculty of Motor Sciences, Université Libre de Bruxelles, Brussels, Belgium;
authors.forename: Vitalie
authors.initials: V
authors.lastname: Faoro
authors.forename: Sandrine
authors.initials: S
authors.lastname: Huez
authors.forename: Rebecca
authors.initials: R
authors.lastname: Vanderpool
authors.forename: Herman
authors.initials: H
authors.lastname: Groepenhoff
authors.forename: Claire
authors.initials: C
authors.lastname: de Bisschop
authors.forename: Jean-Benot
authors.initials: JB
authors.lastname: Martinot
authors.forename: Michel
authors.initials: M
authors.lastname: Lamotte
authors.forename: Adriana
authors.initials: A
authors.lastname: Pavelescu
authors.forename: Hervé
authors.initials: H
authors.lastname: Guénard
authors.forename: Robert
authors.initials: R
authors.lastname: Naeije
mesh_terms: D000064:Acclimatization; D000328:Adult; D000531:Altitude; D015150:Echocardiography, Doppler; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000208:ethnology / Q000503:physiopathology; D000860:Hypoxia / Q000208:ethnology / Q000503:physiopathology*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009390:Nepal / Q000453:epidemiology; D010101:Oxygen Consumption; D010568:Peru / Q000208:ethnology; D010641:Phenotype; D011651:Pulmonary Artery / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011653:Pulmonary Diffusing Capacity; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D018609:Tibet / Q000208:ethnology; D055815:Young Adult
keywords: Quechua; Vo2 max; highlanders; lung diffusion; pulmonary arterial pressure