This one is harder than it looks! The stability ball adds an extra balance element to the traditional 1 arm row which really challenges the core muscles. Start with the right hand on the ball, the right foot on the floor, and the left leg extended straight back. If you do yoga, you will recognize the warrior 3 pose
Using a 10-20 lb dumbbell, pull the left elbow straight up engaging the muscles of the upper middle back. Keep your abdominal muscles tight, squeeze the left thigh and glute muscles, toes pointed. Resist the urge to drop the leg.....keep it straight and elevated. Repeat 10-20 times per side.