EMPLOYEE ATTEMPTED TO LIFT A 4'X8'X1/4"" SHEET OF STEEL WITHOUT ASKING FOR HELP OR USE OF EQUIPMENT; WHILE LIFTING THE PLATE, HE MADE A TWISTING MOTION & FELT A SHARP PAIN TO THE LEFT SIDE OF H IS MIDDLE BACK. HE WAS SENT TO THE DOCTOR FOR EXAMINATION, WHERE HE WAS GIVEN A SHOT AND PUT ON LIGHT DUTY.