EMPLOYEE WAS WORKING IN THE REPLACEMENT OF THE E-14 CHAIN BUCKET ELEVATOR AND HE FELT A PULL IN HIS BACK WHILE LIFTING PIECES WITH THE CAIN PULLEY, AND CONTINUED WORKING UNTIL THE END OF HIS S HIFT. EMPLOYEE COMPLAINED OF BACK PAIN AND WAS SENT FOR MEDICAL EVALUATION. MEDICAL EVALUATION REFERED AS MUSCULAR STRAIN.