EE AND CO-WORKERS WERE INSTALLING HEAT EXCHANGER CHAIN IN ROTARY CEMENT KILN. EE COMPLAINED OF DISCOMFORT DUE TO TIGHT, SORE BACK MUSCLES, ALLEDGEDLY FROM HANDLING THE HEAVY CHAIN STRANDS. HE WAS SEEN BY A PHYSICIAN AND RELEASED TO RETURN TO WORK WITH NO RESTRICTIONS. ON HIS OWN VOLITION, HE TOOK ONE DAY OFF FROM WORK.