But probably the best reason to include this movement in your program is that it will work wonders for your posture by strengthening the muscles that keep your shoulders back and that keep your mid and upper back supported.
Muscles involved: Rhomboids, Middle Trapezius, Upper Latissimus Dorsi, Erector Spinae, Gluteus Maximus, Hamstrings.
Action: Place a swiss ball on the floor in front of you. Stand on your left leg, hold a dumbbell with your left hand, place your right hand on the swiss ball and raise your right leg so that your torso and leg are parallel to the floor.
Start with your left arm fully extended and pull the dumbbell up until your upper arm is just beyond horizontal or the height of your back. Return to the starting position by extending your left arm and repeat for the desired number of repetitions. Then switch sides.
Comments: The leg that is on the floor should be just slightly bent. Brace your mid-section, fire your glutes and straighten the leg that is raised. Also, keep your shoulder over the hand that is on the swiss ball.