Marfan syndrome (MFS) is a distinctive connective tissue disorder that affects multiple organ systems including the heart, bones, ligaments, and eyes, and is associated with significant risk of aortic dissection. Given limited evidence from in-vitro studies, and theoretical concerns, the majority of patients with MFS are restricted from certain physical activities. The lack of exercise and deconditioning have detrimental effects including increasing weakness, joint pain, decreased endurance, and depressive symptoms. Given the significant paucity of data currently existing on the effects of exercise in humans with MFS, and the recent, optimistic findings in rodent models, this pilot trial was established to assess the effects of moderated dynamic exercise in adolescents and young adults with MFS.