Exercise performance of life-long highlanders

Introduction: Life-long exposure to hypobaric hypoxia may induce physiologic adaptations in highlanders that modify exercise performance, although, this has not been conclusively studied. Methods: Life-long residents of the Aksay high altitude plateau (altitude 2700-4200m), Kyrgyz Republic, free of clinically overt cardiopulmonary disease were invited to undergo cardio-pulmonary exercise tests with a progressive ramp protocol to exhaustion on a cycle ergometer. Pulmonary gas exchange, ECG and pulse oximetry were continuously measured. Results: 81 highlanders, mean±SD age 47.9±9.8y, 46% women, SpO2 at rest 88±2% were studied at 3200m. Maximal oxygen uptake (V’O2max) and work rate were near the lower limit of normal sea level reference values. Exercise oxygen desaturation was noted but heart rate and ventilatory reserve were not exhausted (table). In multivariable regression analysis, female (coef -6.38, 95%CI -8.46 to -4.30), BMI (coef -0.33, 95%CI -0.57 to -0.08) and systolic blood pressure at rest (coef -0.07, 95%CI -0.14 to -0.01) were significant predictors of V’O2max (ml/kg/min). Conclusions: The results suggest that exercise performance of highlanders studied at altitude of residence is slightly reduced compared to lowlanders at low altitude. Performance is limited by chronic hypobaric hypoxia that is exacerbated during exercise and by a reduced maximal heart rate. Table. Outcomes during final 30 sec of maximal exercise