To address study hypotheses, the investigators plan to recruit subjects who have been diagnosed with a concussion by participating sports medicine physicians at the Boston Children's Hospital Sports Concussion Clinic. If patients elect to participate, they will undergo their regularly scheduled clinical examination along with two testing components requiring less than 15 minutes of additional time to complete: an instrumented gait balance assessment, a vestibular-ocular motor screen, and a weekly activity survey. Participants with concussion will be matched with control subjects who meet similar demographic characteristics and report to the clinic for other orthopedic injuries that do not affect brain function, gait, or either lower extremity.