Inclusion Criteria:  Present written declaration of consent Healthy Male BMI between 18,5 and 24,9 and body weight between 50kg and 120kg  Exclusion Criteria:  Insufficient linguistic communication Drug abuse or alcohol dependency regular medication except for L-thyroxine or antihistamines known severe eye disease or severely impaired eyesight or hearing a known disease of the cardiovascular system, hypertension higher than 160/90mmHg known pulmonary disease, e.g. bronchial asthma known fractures of the spine or skeletal system of the lower extremity surgery within the last 4 to six months intervention group: fear of heights