Lie face down on the floor with the arms extended and palms facing towards the ground.
Draw in your abdominals and activate your glutes.
Lift chest off floor a few inches (lifting the chest too high off the ground hyperextends the back and places excessive stress on the lumbar spine) while externally rotating your arms and bringing your shoulder blades towards each other and downward.
Hold for 2 seconds.
Return to starting position and repeat for prescribed number of repetitions.