EE STEPPED UP FROM WALKWAY TO BACK OF THE ROCK BREAKER. WHEN HE STEPPED UP, PAIN WAS INSTANT IN THE MID TO LOWER PORTION OF HIS BACK. EE THEN NOTIFIED SUPERVISOR. EE SAID HE COULD WORK THE REST OF THE SHIFT. NEXT MORNING EE'S PAIN & STIFFNESS VERY BAD. PLANT MGR. TOOK HIM TO PHYSICIAN: MEDICATION AND PHYSICAL THERAPY FOR 1 WEEK AND WAS RELEASED TO RETURN TO WORK SAME DAY.