This exercise is a deceptively challenging exercise to help activate the often pesky Glute Medius. Strengthening this muscle will assist with keeping your pelvis aligned. It is quite often used for eliminating knee and back pain as when the muscle is weak, it causes the hips to cock out to the side which puts the lower back into play and also can put the knee out of optimum biomechanical alignment. You will feel the burn on this one!
This is a great exercise for targeting your lats but one side at a time. It is also a handy one to use if you are attempting rebalance your self in the situation of having one side of the body being weaker than the other. Focus on posture and technique is better achieved doing this motion also.