With a dumbbell in each hand, sit on a decline bench, rest the dumbbells on your knees, and hook your feet under the foot pads. (Or have a spotter hand you the dumbbells after you sit down and hook your feet.)
Lie back on the bench and, as you do so, raise the dumbbells over your upper abdomen.
Flex your elbows a little, and internally rotate your shoulders so that your elbows point out to the sides.
Inhale as you slowly lower the dumbbells in a semicircular motion to your sides until you feel a slight stretch in your chest.
Exhale as you reverse the motion and bring the dumbbells back up over your chest in a hugging movement.
Repeat for the prescribed number of repetitions.
Comments and tips
To preserve your elbow joints, keep your elbows slightly flexed.
Keep the movement slow and controlled.
The reason for internally rotating your shoulders is to better isolate your sternal pectoralis major by bringing the muscle’s origin and insertion into better alignment.
The steeper the angle of the bench, the less your anterior deltoid will contribute as a synergist.
Use the decline dumbbell fly to warm up, pre-exhaust, or burn out your sternal pectoralis major. It is not a major mass-building exercise.