Paranoid schizophrenia is more than sufficient to explain everyrhing you saw and heard. The human voice is a remarkably flexible instrument, for one thing. For another, accounts of 'hysterical strength' are far too common for the phenomenon to be dismissed. Petite women have been known to lift cars when their children were trapped underneath, and teenagers have shown the same capacity when rescuing parents. Generally speaking, there is a price to be paid later in exhaustion and perhaps injury. In Norse culture, it was known as the 'berserkergang' .