WHILE WORKING IN THE 12 RT BELT LINE EE WAS CARRYING ONE PIECE OF SCISSOR RAIL. HE WAS TRYING TO WALK PAST ANOTHER EMPLOYEE WITH OUT HITTING HIM WITH THE RAIL WHEN HE SLIPPED IN THE MUD WHICH CAUSED HIM TO HAVE UNEVEN FOOTING. HE TRIED TO RETAIN HIS BALANCE WHICH PUT UNDO PRESSURE ON THE CENTER PART OF HIS BACK RESULTING IN A PAIN IN MIDDLE OF HIS BACK.