Secure the center of the tubing in the doorjamb at chest level.
Engage abdominal muscles before beginning the exercise.
Secure tubing at top of door. Loop one handle through the other and secure at doorjamb. Stand sideways to door holding the one handle with both hands. Step away from the door until there is tension in the elastic. Feet are wider than hip distance. Begin holding the handle at shoulder height (of shoulder closest to door) extend forward and down to opposite knee. Slowly return to starting position and repeat.