This single arm version of the classic chest exercise is a surprisingly effective torso exercise. Anchor a band approximately chest height and stand side on. With a slight bend in your elbow pull your arm straight across the front of your body pausing at or just beyond the mid-line. Resist the rotational pull of the band by keeping your posture fixed. Slowly release the band back to the start position and repeat. Don't start the exercise with the working arm too far behind the shoulder as this will add unnecessary strain to the joint.