Reverse Fly

Stand with feet hip-width apart, hinge forward at the hips until your torso is roughly 45 degrees to the floor, and let the dumbbells hang below your chest. With a slight bend in your elbows, raise the dumbbells out to the sides in a wide arc until your arms are roughly in line with your shoulders. Squeeze your rear delts at the top, then lower with control.

Pro Tips

• Keep your torso angle fixed — do not rise up as you lift the weight
• Think about pulling your elbows toward the ceiling rather than swinging the dumbbells
• Use a light weight and focus on the squeeze — rear delts respond to volume, not load

Muscles worked

Primary: Posterior (rear) deltoid head — the dumbbell reverse fly targets the rear delt through horizontal shoulder abduction with the arm in a hinged, forward-bent position, which places the rear delt in a position of direct loading that rows and face pulls approach from different angles.

Supporting: Rhomboids and middle trapezius (scapular retraction at the top of the arc), infraspinatus and teres minor (external rotators of the shoulder — active throughout the wide arc movement), lower trapezius (scapular depression and stabilisation).

Common mistakes

Torso rising during the raise: Lifting the upper body to help the dumbbells rise turns the exercise into a hybrid row/raise hybrid that loads the traps more than the rear delts. The torso angle should stay fixed throughout the set at approximately 45 degrees.

Excessive elbow bend: A slight bend (10–15 degrees) is appropriate to relieve stress on the elbow joint. A significant bend (more than 30 degrees) reduces the lever arm and turns the movement into more of a rear delt row. Maintain a nearly straight arm position throughout.

Going too heavy: The rear deltoid is a small muscle with a small cross-sectional area. Heavy dumbbells in the reverse fly cause the traps and rhomboids to dominate the movement and the rear delt to lose its targeted loading. A weight that allows a clear squeeze at the top and a controlled eccentric is the correct choice — for most people this is surprisingly light.

No pause at the top: The rear delt’s peak contraction occurs at the top of the movement when the arms are roughly in the plane of the shoulder. A brief squeeze and hold at the top is the most effective way to engage the rear delt maximally and confirm it, not the traps, is the working muscle.

Programming notes

The reverse fly is a direct rear delt isolation exercise best used as a complement to face pulls (which also target the rear delt with an external rotation component) and rows (which train the rear delt indirectly). Because the rear delt is often undertrained in programmes that emphasise horizontal pressing, direct reverse fly work helps maintain shoulder balance and health.

Typical programming: 3–4 sets of 12–20 repetitions, placed at the end of pull or shoulder sessions. The rear delt is highly responsive to volume and moderate loads — accumulating sets across the week (even 2–3 sets at the end of multiple sessions) is more effective than one large volume day.

Frequently asked questions

How do I know if my rear delts are actually working, or if my traps are taking over?

If your traps are dominating, you will feel the effort high on the back of your neck and upper back rather than in the back of your shoulder. At the top of each rep, pause briefly and squeeze — you should feel the contraction specifically in the posterior deltoid, the rounded muscle at the back of the shoulder cap. If you cannot isolate that sensation, reduce the weight significantly and slow the movement down. Keeping the torso fixed at 45 degrees and maintaining a nearly straight arm are the two technique points that most reliably keep load on the rear delt.

Is the reverse fly better than face pulls for rear delt development?

They are complementary rather than interchangeable. Face pulls train the rear delt alongside external rotation, making them excellent for shoulder health and rotator cuff reinforcement. The reverse fly isolates horizontal shoulder abduction in a way that places more direct stress on the posterior deltoid with less involvement from the biceps and upper traps. For shoulder balance and hypertrophy, most lifters benefit from including both movements — face pulls early in the session and reverse flies as a finisher with higher rep ranges.

What rep range works best for the reverse fly?

The rear delt is a muscle with a high proportion of slow-twitch fibres and responds well to moderate-to-high rep ranges. Sets of 15–25 reps with a controlled tempo and a pause at the top tend to produce better rear delt development than heavier, lower-rep work. This is also practical because heavier loads in the reverse fly encourage trap and rhomboid takeover. If you are programming this for hypertrophy, prioritise accumulated weekly volume — three sets of 20 at the end of two or three sessions per week outperforms one heavy dedicated session.