You’re probably neglecting them. Most people do. You walk into any commercial gym and see rows of guys hammering their front delts with overhead presses or chasing a "chest pump" until their shoulders round forward like a Quasimodo audition. The result? A physique that looks cave-in and shoulders that scream in pain every time you try to reach for something on a high shelf. That's where the rear delt reverse fly comes in, or at least, where it’s supposed to come in.
It’s honestly one of the most misunderstood movements in the hypertrophy world. People treat it like an afterthought, something to tack onto the end of a workout with zero intensity. Or worse, they ego-lift, swinging heavy dumbbells with so much momentum that their rhomboids and traps do 90% of the work. If you aren't feeling that deep, localized burn right on the back of your shoulder, you’re basically just doing a bad row.
The rear deltoid—the deltoideus posterior if you want to be fancy—is tiny. It’s a small muscle with a specific job: horizontal abduction, external rotation, and extension of the humerus. When you butcher the rear delt reverse fly, you aren't just missing out on "3D shoulders." You're actually setting yourself up for chronic impingement.
Why the Rear Delt Reverse Fly Is Non-Negotiable
Stop thinking about this as just a "bodybuilding" move. It’s postural insurance. Most of us spend our lives in "internal rotation"—typing, driving, scrolling. This shortens the pectorals and weakens the posterior chain. The rear delt reverse fly acts as the corrective counterbalance.
According to Dr. Bret Contreras, often cited for his EMG studies on muscle activation, the rear delts require high volume and specific angles to actually grow. They don't get hit nearly as much as you think during heavy rows. In a standard barbell row, your lats and mid-traps are the primary movers. Without a dedicated isolation move like the reverse fly, that posterior head stays flat and weak.
The Mechanics of the "Perfect" Rep
Let's get tactile. If you’re using dumbbells, don't stand upright. You need to be bent over, almost parallel to the floor. Gravity only works one way—down. If you're standing at a 45-degree angle, you’re hitting your lateral delts and upper traps. Lean over. Get uncomfortable.
Now, look at your hands. Stop gripping the dumbbells like your life depends on it. A white-knuckle grip often leads to forearm and bicep takeover. Try a neutral grip (palms facing each other) or even a slightly internally rotated grip (pinkies up). Think about "throwing" the weights out to the side walls, not pulling them up to the ceiling. It’s a wide arc.
- The Lead: Lead with your elbows, not your wrists.
- The Path: Keep the weights in line with your shoulders or slightly in front of them. Pulling too far back shifts the load to the traps.
- The Range: You don't need a massive range of motion. Once your arms are parallel to the floor, the rear delt is fully contracted. Going higher just crunches your scapula together.
Dumbbells vs. Cables vs. Machines
There is a huge debate in the coaching world about which tool is king for the rear delt reverse fly. Honestly? They all have a place, but they aren't equal.
Dumbbells are the most accessible. But they have a "dead zone." At the bottom of the movement, when your arms are hanging down, there is zero tension on the muscle. The resistance only kicks in halfway through the rep. It's inconsistent.
Cables are arguably superior for pure hypertrophy. Because the weight stack is hanging, there is constant tension from the moment you start the pull until you finish. If you use a cable crossover machine, try crossing the cables (left hand grabs right cable, right hand grabs left cable) without handles. Just grab the balls on the ends of the wires. This allows for a more natural path of motion and keeps the focus strictly on the delt.
The Pec Deck (Reverse) is the favorite of many pro bodybuilders like Mike Israetel. Why? Stability. When your chest is pressed against a pad, you can't cheat. You can't use your legs or lower back to swing the weight. If you struggle with "mind-muscle connection," the machine version is your best friend. It forces the isolation that dumbbells often fail to provide.
The Mistakes That Are Killing Your Gains
You see it every day. The "shrug-fly." This happens when the weight is too heavy. The trainee initiates the move by shrugging their shoulders up toward their ears. This engages the levator scapulae and upper traps. Your shoulders should stay down and "packed." Imagine you’re trying to keep your shoulder blades away from your ears throughout the entire set.
Another big one: The Scapular Retraction Trap. Most people think they need to squeeze their shoulder blades together at the top of a rear delt reverse fly.
Wrong.
If you’re squeezing your shoulder blades, you’re doing a mid-trap exercise. To isolate the rear delt, you actually want to keep your shoulder blades relatively still—or even slightly protracted (spread apart). Focus on moving the arm bone away from the body, not the shoulder blade toward the spine. It’s a subtle difference that changes everything.
Frequency and Volume: How Much is Enough?
Rear delts are resilient. They are composed of a high percentage of slow-twitch muscle fibers because they are postural muscles. This means they can handle—and actually require—higher frequency. Training them once a week on "shoulder day" isn't going to cut it if you have lagging development.
Try hitting them 3 times a week.
You don't need to go heavy.
Sets of 15–25 reps are the sweet spot.
Think about "pumping" blood into the area rather than moving massive iron.
"The rear delt is a muscle of detail. You can't bully it into growing; you have to coax it with precision and high-tension volume." — Paraphrased from common coaching wisdom.
Real-World Variations to Try
If the standard version feels stale, try the Incline Bench Rear Delt Fly. Lie chest-down on a bench set to a 30-degree incline. Let your arms hang. This version removes all the stability requirements from your lower back and hamstrings. You can purely focus on the back of the shoulder.
Then there’s the Rear Delt Destroyer Set, popularized by John Meadows (the "Mountain Dog"). You take a heavy pair of dumbbells, do a set of partial-range "swings" for 40 reps, then drop to a lighter weight for 20 reps, then finish with a 10-second isometric hold. It’s brutal. It’s painful. But it works because it bypasses the neurological "shut off" that happens when we get tired.
The Role of Genetics and Bone Structure
We have to be realistic. Some people have a skeletal structure that makes the rear delt reverse fly feel incredibly natural. Others, with narrower clavicles or more anteriorly tilted pelvises, might struggle to "find" the muscle. If you’ve tried everything and still don't feel it, check your elbow position.
Slightly bending your elbows is fine, but don't let the angle change during the rep. If your elbow goes from bent to straight, you’re using your triceps. Lock that angle in. Whether it's a 10-degree bend or a 30-degree bend, keep it static.
👉 See also: Measles in Orange County: Why This Old Virus Keeps Making a Comeback
Actionable Steps for Your Next Workout
Don't just read this and go back to your old routine. If you want better shoulders, you have to change the stimulus.
- Start with the rear delts: Most people save them for last when they’re exhausted. Flip the script. Do your rear delt reverse fly at the beginning of your workout when your nervous system is fresh.
- The 2-Second Pause: At the top of every rep, hold the contraction for two full seconds. If you can’t hold it, the weight is too heavy.
- Film Yourself: Set up your phone from a side profile. Are you swinging? Is your back arching? Most people are shocked by how "sloppy" their form looks compared to how it feels in their head.
- Vary the Angle: One day use cables at shoulder height. The next session, set the cables high and pull downward at a 45-degree angle. This hits different fibers of the posterior head.
The rear delt reverse fly isn't a "glamour" lift like the bench press. You won't be posting your 1RM on Instagram. But it is the difference between a physique that looks "done" and one that looks like it's still under construction. It’s the difference between healthy, mobile joints and a rotator cuff surgery in your 40s.
Stop swinging. Start feeling. Lower the weight, tuck your chin, and focus on the stretch. Consistency here pays off in a wider look and a more stable overhead press.
Next Steps for Implementation:
Incorporate the chest-supported dumbbell version into your next "Pull" or "Shoulder" session. Perform 4 sets of 20 reps with a focus on a 3-second eccentric (lowering) phase. This increased time under tension will force the mind-muscle connection that is often missing in faster, more explosive movements. Monitor your shoulder positioning to ensure no shrugging occurs during the sets. Over the next four weeks, gradually increase the total weekly sets by two to test your recovery capacity for this specific muscle group.