EE ALONG WITH OTHER CO WORKERS WAS PREPARING A SITE FOR A CONCRETE POUR. HE AND CO WORKER WERE LIFTING A PRE TIED REBAR BEAM, WEIGHTING ABOUT 100 LBS AND HAD TO CARRY IT OVER A SHALLOW TRENCH TO PUT IT IN PLACE. BECAUSE OF THE AWKWARD POSITION HE WAS IN, HIS BACK TWISTED CAUSING A STRAIN WITH RESULTING MUSCLE SPASMS. HIS TREATING PHYSICIAN DIRECTED HIM TO REFRAIN FROM EVEN ANY LIGH