Patients with hypertrophic obstructive cardiomyopathy and New York Heart Association Class I-II under stable treatment with mavacamten (at least 12 weeks without change of dosage) and a peak left ventricular outflow tract obstruction \<50mmHg undergo either 6 weeks of structured moderate intensity endurance and resistance training (supervised, 3x/week, intervention, IT) or usual care (UC). Patients within 1 hour of travel to the training venue will be referred to IT, while those with more than 1 hour will join UC. At baseline (visit 1, V1) and after 6 weeks of exercise intervention (visit 2, V2) all patients undergo a medical exam, resting and stress echocardiography and receive a questionnaire on the quality of life (Kansas City Cardiomyopathy Questionnaire). Cardiac biomarkers are assessed. 3 hours after stress echocardiography cardiopulmonary exercise testing is performed to measure peak oxygen consumption (VO2peak). The primary outcome is the change of VO2peak from V1 to V2. Secondary outcomes include safety, changes in cardiac biomarkers, resting and stress echocardiographic variables, quality of life and variables of cardiopulmonary exercise testing.