EE WAS CLIMBING ON THE STEPS OF HIS HAUL UNITWHEN HE FELT A PAIN IN HIS BACK AS HE LIFTED HIS LEFT FOOT TO STEP ON THE ACCESS LADDER EE HAD A PREXISTING CONDTION WHICH WAS APPARENTLY AGGRAVA TED BY CLIMBING INTO HIS HAUL UNIT. HIS CONDITION WAS INITIALLY TREATED 1ST AID & HAS NOW BECOMEA MEDICAL REPORTABLE INCIDENT