Concussion or mild traumatic brain injury (mTBI) is a public health problem and it is imperative that efficacious treatment protocols be developed to reduce the morbidity associated with PCS in adolescents. In adolescent athletes, timely return of normal neurocognitive function and return to sports safely is critical to normal development. The proposed study will fill a critical gap by systematically evaluating the potential efficacy of an aerobic training intervention for management of PCS in adolescents. To our knowledge, this will be the first randomized controlled study to evaluate the efficacy of aerobic training for treatment of PCS in adolescents as soon as four weeks after injury. The study will also improve our understanding of the pathophysiology of PCS and the biologic influence of aerobic training on PCS. The proposed study will fill a critical gap and inform the development of larger studies to assess the efficacy, and if proven efficacious, optimize the timing and intensity of aerobic training treatment protocols, thus transforming the care and limiting the adverse public impact of this condition.