EE WAS CLIMBING ONTO THE DRAGLINE (RIGHT SHOE) USING THE REAR INSIDE BOARDING LADDER. AS HE WAS CLIMBING UP HE USED THE CATWALK ABOVE THE LADDER TO PULL HIMSELF UP & FELT A TWISTING SENSATION IN HIS LOWER BACK. EE BECAME EXTREMELY STIFF AS THE SHIFT PROGRESSED & HAD TROUBLE WALKING BY THE END OF HIS SHIFT.