"HOOAH!" A case of pneumomediastinum in the military training environment; Hamman's sign 71 years later.

A previously healthy 20-year-old male trainee developed chest pain, shortness of breath, and neck pain after repeatedly shouting "Hooah!" during a motivational squad competition. He was found to have developed a pneumomediastinum with soft tissue crepitus of the neck. He had an uneventful recovery. Unique to the military training environment, vigorous shouting, including "Hooah!" as a motivational stimulus, can have barotraumatic consequences. The term "spontaneous" as applied to a pneumomediastinum diagnosis is examined and the auscultatory finding of "Hamman's sign" is reviewed.