EE WAS SWINGING A 80 LB SLEDGE HAMMER TO ALIGN BOLT HOLES ON COOLER TUBE TO ELBOWS. HE FELT SLIGHT DISCOMFORT IN HIS LOWER BACK BUT DID NOT REPORT IT. HE REPORTED ON 2/14 THAT HIS BACK WAS HU RTING & NEEDED TO SEE A PHYSICIAN. DIAGNOSED AS LOWER BACK STRAIN & PUT ON RESTRICTED DUTY.