Normobaric Hypoxia Exposure on Substrate Oxidation Pattern: Sex Differences

Hypoxic exposure has been associated with a metabolic perturbation that might affect basal energy expenditure (BEE).

The aim was to examine the metabolic response during hypoxic exposure of men and women adults.

Crossover design with two experimental trials: normoxic and hypoxic exposure.

Twenty-nine healthy subjects (14 women) participated in (1) control study (NOR), subjected first to normoxic exposure (FiO₂ = 20.9%) and (2) after that, to passive normobaric hypoxic exposure study (HYP) (FiO₂ = 15%). Respiratory gases and blood glucose samples were recorded every hour in hypoxia chamber (8 points in total), and blood lactate samples were collected at baseline, at 4 and 7 h to exposure.

In females, basal energy expenditure was significantly higher at 2h, 4h, 6h and 7h compared with NOR group. Also, BEE was lower in females compared with men from 2h of hypoxia exposure. In the HYP group the blood lactate concentration increased significantly at 4h and 7 h relative to NOR group (P < 0.05) in males.

An exposure to moderate normobaric hypoxia did not alter metabolic response, but induced a different response on substrate oxidation in adults men and women.