The subjects arrive in the CRU after a 12 hours overnight fast to perform a 30-minute movement activity with individually adapted exercise intensity on the treadmill.

The 30-minute movement activity on the treadmill will be completed by each subject once under normobaric normoxic and once under normobaric hypoxic conditions (equivalent to approximately 3000 meters above sea level) in a randomized episode.

A drop of capillary blood (20 µl) will be collected from the hyperemic earlobe for metabolomic analysis at the times t = 0 min (before starting), 10 min, 20 min and 30 min during the activity, and t = 50 and 60 min taken in the recovery phase. The oxygen saturation and heart rate will be determined at the same time points by pulse oximetry and heart rate monitoring, as well as blood gas analyses and subjective self-perception of energy availability on a quantitative scale throughout exercise.