EMPLOYEE REPORTED: PERFORMING THE JOB OF MINE EXAMINER, WHEN TRAVELING ALONG THE MINE TRAVELWAY, HE OBSERVED A TIMBER LAYING ON THE MINE FLOOR, HE STOPPED HIS RIDE, UNBOARDED AND ATTEMPTED TO LIFT AND MOVE THE TIMBER, WHEN LIFTING THE TIMBER EXPERIENCED PAIN TO HIS BACK. PAIN WORSENED DURING HIS SHIFT.