INDIVIDUAL WAS CLIMBING A LADDER TO FILL A GENERATOR GAS TANK. WHILE LIFTING A 5-GALLON GAS CAN,SHE TURNED WRONG & PULLED A BACK MUSCLE. SHE REPORTED TO WORK THE NEXT DAY BUT COULD NOT PERFORM HER DUTIES. SHE WAS TAKEN TO THE HOSPITAL, TREATED FOR MUSCLE SPASMS & MISSED ONE DAY OF WORK.