WHILE TRYING TO LIFT A 78 LB BOX TO PLACE IT IN A VEHICLE FOR TRANSPORT TO THE PLANT WAREHOUSE, EMPLOYEE REALIZED THE BOX WAS TOO HEAVY AFTER GETTING IT 3 OR 4 INCHES UP. WITHIN 1/2 OF AN HOUR EMPLOYEE WAS EXPERIENCING SEVERE PAIN IN RIGHT BUTT CHEEK AND DOWN BACK OF RIGHT LEG.