Physiological measurements
ScO

Arterialised carbon dioxide
Descriptive statistics of the physiological parameters at different altitude, activity (rest and exercise) and mask conditions are shown in Descriptive statistics of main parametersNX, normoxia; HH, hypobaric hypoxia. Effects of mask (m), altitude (a), exercise (e) and interaction (×) are highlighted in the first column. 


Linear mixed models were used, except for ScO

Arterialised carbon dioxide partial pressure (PaCOArterialised oxygen saturation (SaONo effect of mask condition was detected on T