Still sitting at the edge of your chair, extend both your legs. Place the center of the tube around the arches of your feet (better to keep your shoes on to prevent the tubing from hurting you). Hold one end in each hand, palms facing the floor and wrists neutral. Sit up tall.

Slowly bend your elbows and pull the tube towards you, pushing your elbows towards the back. As you reach behind, squeeze your back and then slowly extend the arms again. Release the tube very gently -- letting go suddenly can cause injury.

Do 12-16 repetitions, rest and repeat.