Developmental Effects Determine Submaximal Arterial Oxygen Saturation in Peruvian Quechua

Andean high altitude natives show higher arterial oxygen saturation (Sao₂) during exercise in hypoxia, compared to acclimatized sojourners. In order to evaluate the effects of life-long exposure to high altitude on Sao₂, we studied two groups of well-matched, self-identified Peruvian Quechua natives who differed in their developmental exposure to hypoxia before and after a 2-month training period. Male and female volunteers (18-35 years) were recruited in Lima, Peru (150 m). The two groups were: a) Individuals who were born and raised at sea-level (BSL, n=34) and b) Individuals who were born and raised at high altitude (BHA, n=32), but who migrated to sea-level as adults (>16 years old). Exercise testing was conducted using a submaximal exercise protocol in normobaric hypoxia in Lima (BP=750 mmHg, Fio₂=0.12), in order to measure Sao₂ (%), ventilation (VE L/min) and oxygen consumption (Vo₂, L/min). Repeated-measures ANOVA, controlling for VE/VO₂ (L/min) and sex during the submaximal protocol showed that BHA maintained higher Sao₂ (%) compared to BSL at all workloads before (p=0.005) and after training (p=0.017). As expected, both groups showed a decrease in Sao₂ (%) (p<0.001), as workload increased. Resting Sao₂ levels were not found to be different between groups. The results suggest that developmental exposure to altitude contributes to the maintenance of higher Sao₂ levels during submaximal exercise at hypoxia.