The Reverse Fly Is a Back and Shoulder Exercise, Here’s How

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Ask two people if the reverse fly targets the back or shoulders, and one will probably argue the former and the other the latter. The debate is mixed because the exercise moves the arms behind the body. This leads to confusion as to whether or not it’s for the deltoids or the upper back.

The reverse fly is predominantly a shoulder exercise since it targets the rear delts. It can also be used as an upper back exercise by squeezing the shoulder blades at the top to emphasize the traps and rhomboids.

Below I’ll explain why this exercise can target the back or shoulders along with form adjustments to prioritize one area over the other.

Why the Reverse Fly Can Be for Back or Shoulders

A properly performed reverse fly mainly utilizes horizontal shoulder extension. This is the function that occurs as the arms travel from in front of the body, toward the back. The muscles responsible for this function are the rear delts.

As a general rule, reverse flys are considered a shoulder exercise. This is because the prime movers are the rear deltoids, which are located on the backside of the shoulder muscles.

This makes reverse flys a common rear delt isolation exercise during a shoulder workout. They are also used for strengthening the infraspinatus and teres major, which are rotator cuff muscles of the shoulders.

Scapular retraction, or squeezing the shoulder blade together, is another action that occurs with the reverse fly. This recruits the traps and rhomboids, especially toward the peak contraction.

Shoulder retraction usually isn’t emphasized and is sometimes deemed “incorrect”, especially if the rear delts are the muscle you’re trying to target. However, retraction should occur slightly and naturally throughout the movement so the upper back can stabilize the shoulder blades.

Reverse flys are often placed at the end of back workouts to burn out the rear delt and upper back muscles. That’s because both areas are recruited during the exercise, so this arrangement helps to maximize their stimulation.

If you have trouble engaging your traps with rows or shrugs, including reverse flys toward the end of your back workout can improve the muscle connection. To shift the focus onto these muscles, emphasize the shoulder squeeze as you lift the weights.

I’d suggest using heavier weights when doing them this way since the traps respond well to heavy loading. The downside is that you won’t get as much rear delt stimulation since you’re not lifting the brunt of the load by moving the arms out, then back. Rather you’re mainly pulling straight back, using the traps.

Looking to isolate your rear delts on a back day, but not sure if it’s a smart move? This article explains why and how you can do that effectively!

Here’s a table showing the main shoulder and back muscles that are involved during the reverse fly:

Shoulder Muscles Worked With Reverse Flys	Back Muscles Worked With Reverse Flys
Rear Deltoids	Middle Trapezius
Teres Minor	Lower Trapezius
Infraspinatus	Rhomboids

Although the reverse fly is coined as a rear delt exercise, don’t fall into the trap of thinking you can only do it for this muscle. If doing it with modified form cues helps improve your upper back, then by all means do it for that area instead.

Now I’ll explain a few more form tweaks you can make to emphasize the traps and rhomboids or rear delts even more.

How To Use Reverse Flys as a Back Exercise

Conversely to what I mentioned earlier, horizontal shoulder extension isn’t always just performed by the rear delts. EMG data has discovered the lower and middle traps to elicit high activation when performing this anatomical motion.

Remember, horizontal extension is the movement that occurs when the arms move behind the back in a reverse fly. During this motion, trap activation is particularly prevalent when you lie face down with your palms face forward, while your arms are held away from the body.

With these factors in mind, the reverse fly can be transformed into a mostly back-specific exercise by:

1. Lying face down on a flat bench.
2. Relax your arms toward the floor with your thumbs pointed toward the ceiling and palms facing forward.
3. Hold a light dumbbell in each hand.
4. With your elbows locked, raise your arms toward the ceiling until your hands are elevated above your back.
   • Your arms should be in line with your shoulder blades, forming a 90-degree angle with your waist.
     • This has been shown to elicit an optimal level of lower-middle trap involvement.
5. Squeeze your shoulder blades at the top.
6. Perform 3-4 sets of 10-15 reps using moderately heavy weights.

This variation doesn’t completely cut out shoulder stimulus as the rotator cuffs are involved to stabilize the shoulder joints. However, the rear delts will receive much less tension than normal. Especially as the shoulder blades retract heavily at the top, transferring tension onto the upper back.

How To Use Reverse Flys as a Shoulder Exercise

The rear delts are inserted diagonally on the back of the shoulder. They are highly engaged when the arms are angled at 45 degrees to the ribcage during horizontal extension. Holding the arm at this angle while performing the movement engages the infraspinatus well too.

Think about performing an arcing motion with your arms, rather than a pulling motion. This will help minimize shoulder blade retraction, allowing you to focus on horizontal extension for maximum rear delt tension.

To perform reverse flys for the shoulders:

1. Lean your upper body to 45 degrees with the floor.
2. Hold dumbbells with your palms facing each other.
3. Relax your arms toward the floor with a slight bend in your elbows.
4. Swing your hands away from each other, while simultaneously driving them toward the ceiling and slightly towards your hips.
   • Raise them toward your hips to create that 45-degree angle between your arms and ribcage.
5. Reverse your arms toward the floor beneath your chest.
6. Repeat for 3-4 sets of 12-20 reps using light weights.

If I had to class the reverse fly as being a shoulder or back exercise I’d have to say shoulders. When performed classically, it works the infraspinatus and rear delts more than the upper back.

Like I said before though, it can still be used as an isolation exercise for the traps and rhomboids. The important thing to be aware of is the differences in muscle activation that will occur depending on how you perform the motion. This will allow you to work the intended muscle more effectively.

• Emphasize scapular retraction for the upper back.
• Arc the weights out and up for the rear delts.