This is an isolation movement that targets the deltoids (posterior). Primary muscles used in this exercise are the posterior deltoids. Secondary muscles used in this exercise are the traps and forearms.
To perform bent over side laterals sit on the edge of the bench and lean forward gripping a dumbbell in each hand, holding them behind your feet. With your elbows slightly bent, raise the dumbbells by your side with a forceful movement slightly higher than shoulder height. Lower the weight back down to the starting position in a controlled slower manner. Repeat the process.