RecruitingBehavioural interventionExercise Reset for Concussion in a Military EnvironmentOur primary objective is to show that early, personalized aerobic exercise treatment safely improves concussion recovery, speeds RTD, and reduces persistent symptoms in CSM. Our secondary objectives include demonstrating the clinical utility of our March-in-place test and determining fundamental mechanisms for the effect of exercise rehabilitation on concussion recovery. We will conduct a prospective four-year multicenter mechanistic treatment (Phase 3) RCT in CSM of personalized sub-threshold aerobic exercise added to the PRA compared with the PRA alone. Non-concussed, age-matched SM will serve as a healthy control group (HC) for comparing CSM to normal physiology and to control for the effect of time and of aerobic exercise.