Low altitude baseline measurements will be performed in Zurich (460m asl) including Echocardiography, Right heart catheterization, six-minute walk test (6MWT), pulmonary function test, clinical assessment and blood gas Analysis. Randomly assigned to the order of testing, the participants will be tested under simulated altitude (FiO2: 15.1% with the "AMC Altitrainer") and shamed altitude with the same device. Several times within the exposure, the pulmonary artery pressure and the right heart function will be assessed by echo under exercise.
