Concussions represent 70% to 90% of all traumatic brain injuries, creating an increasingly major and costly health concern. In adolescent athletes, sports-related concussions account for an estimated 2.2 million emergency department visits per year in the United States. The historic standard for treatment of sports-related concussions consists of physical and cognitive rest until symptoms resolve, followed by a stepwise gradual return to activity. However, the current consensus among experts is that there is insufficient evidence for prescribing complete physical and cognitive rest until asymptomatic after acute sports-related concussions. Moreover, unnecessary delays in activity initiation for athletes may have detrimental effects on physical fitness and mental health, leading to additional subspecialist consultations and more extensive use of medical resources, driving up the cost. Thus, we recommend initiating early subthreshold, symptom-limited aerobic exercise as rehabilitation for adolescents who have sustained an acute sports-related concussion, especially given the overwhelming amount of recent high-quality, data-driven evidence sufficiently demonstrating symptomatic improvement and decreased recovery time with this strategy.