EMPLOYEE WAS RE-STACKING A PALLET OF 100 LBS BAGS FULL OF CRUSHED LIMESTONE ON 07/18/03. EMPLOYEE REPORTED TO SUPERVISOR VIA VOICE MAIN AT 10:00 AM ON 7/21/03 THAT HE HAD STRAINED STOMACH MUSC LES STACKING BAGS ON 07/18/03. EMPLOYEE WAS SENT TO COMPANY MD AT 8:00 AM ON 07/22/03 FOR TREATMENT. EMPLOYEE WAS RELEASED TO RESTRICTED DUTY - 10-12 LBS PUSHING, PULLING, LIFTING. STRAINED S