Effect of Acetazolamide on Maximal Exercise Performance in Lowlanders Older Than 40 Years at Altitude

This is a randomized, placebo-controlled, double-blind parallel trial evaluating the effect of acetazolamide intake on the maximal exercise performance in lowlanders older than 40 years travelling to altitude. Participants living in the Bishkek area, Kyrgyzstan (760m), will be transferred by car within 4h to the Tuja Ashu high altitude clinic (3'100 m), and stay there for 2 days. Acetazolamide 375mg/day (or placebo), will be administered before departure at 760 m and during the stay at altitude. Outcomes will be assessed during the stay at 3'100 m. An interim analysis will be carried out when 80 participants will have completed the study or after the first year. The Peto's method will be used and the trial will be stopped when pre-specified futility boundaries were crossed.