EE WAS LIFTING 30-40# ROCKS FROM GROUND & THROWING THEM IN A LOADER BUCKET. HIS BACK WAS FEELING STIFF ALL MORNING. HE WENT TO LIFT ANOTHER ROCK & WHEN HE STARTED TO LIFT THE ROCK HIS BACK MUS CLES STARTED TO SPASM - SHARP PAIN IN HIS BACK - DROPPED TO HIS KNEES WITH PAIN. HAD DIFFICULTY STANDING UP. GIRLFRIEND PICKED HIM UP & TOOK HIM TO EMERGENCY ROOM.