You’re probably doing them wrong. Honestly, most people at the gym are. They grab the heaviest weights they can find, swing their arms like they’re trying to take flight, and wonder why their upper back still looks flat. It’s frustrating.
Dumbbell reverse flys are one of those movements that look simple but are incredibly easy to mess up. If you feel this more in your neck or your traps than in the back of your shoulders, you've got a problem. The rear deltoid is a tiny muscle. It doesn’t need massive weight; it needs precision.
Most lifters treat this like a row. It isn't a row. When you row, you’re using your lats and your rhomboids to pull weight toward your torso. When you perform a reverse fly, you are trying to isolate the posterior deltoid by moving the weight in an arc. It's a subtle difference that makes a massive impact on your physique.
The Anatomy of a Perfect Rep
Let’s get into the weeds for a second. Your shoulder is a ball-and-socket joint with three distinct heads: the anterior (front), lateral (side), and posterior (rear). We spend all day hunched over keyboards, which rounds our shoulders forward. This makes the front delts tight and the rear delts weak and overstretched.
To fix this, you need to master the horizontal abduction of the humerus. That’s just a fancy way of saying "moving your upper arm away from your chest toward your back."
Start by hinging at the hips. You want your torso almost parallel to the floor. If you stand too upright, you're just doing a weird version of a side lateral raise. Gravity needs to be working against the back of your shoulder, not the top of it.
Hold the dumbbells with a neutral grip—palms facing each other. Keep a slight bend in your elbows. This is non-negotiable. If your arms are perfectly straight, you’re putting unnecessary torque on the elbow joint. If they’re bent too much, you’re basically doing a row. Find that sweet spot.
Now, pull the weights out to the sides. Imagine you’re trying to touch the walls on either side of you, rather than pulling the weights "up." This "reaching out" cue is a game-changer. It helps disengage the traps and keeps the tension right where you want it.
💡 You might also like: Finding the Healthiest Cranberry Juice to Drink: What Most People Get Wrong
Common Mistakes That Kill Your Gains
Stop ego lifting. Seriously.
I see guys grabbing 40-pound dumbbells for reverse flys. Unless you're a professional bodybuilder, you have no business using 40s for this. Most seasoned lifters find their "sweet spot" between 10 and 20 pounds. Why? Because the moment the weight gets too heavy, your body recruits the rhomboids and middle traps to help. You'll know this is happening if you feel your shoulder blades slamming together at the top of the movement.
While some scapular retraction is inevitable, it shouldn't be the primary driver. If your goal is rear delt isolation, try to keep your shoulder blades relatively still.
Another big one: momentum. If you have to bounce your knees to get the weight up, it’s too heavy. You’re using physics, not muscle. Slow it down. Take two seconds to go up, hold for a split second at the top, and take three seconds to lower it. The eccentric (lowering) phase is where a lot of the muscle damage—and subsequent growth—happens. Don't just let the weights drop.
Variations That Actually Work
If the standard standing version hurts your lower back, you aren't alone. Hinging over like that puts a lot of shear force on the lumbar spine.
Try the Chest-Supported Reverse Fly.
Set an incline bench to about 30 or 45 degrees. Lay face down with your chest against the pad. This completely removes the "cheat factor." You can’t use your legs or lower back to swing the weight. It’s pure, isolated shoulder work. It’s humbling. You might find that the 15-pound dumbbells you used while standing are now way too heavy. That’s good. It means you’re finally hitting the right muscle.
📖 Related: Finding a Hybrid Athlete Training Program PDF That Actually Works Without Burning You Out
What about hand position?
Most people use a neutral grip (palms facing). But according to a study published in the Journal of Strength and Conditioning Research, using a pronated grip (palms facing down/back) can actually increase rear delt activation. When your palms face down, it rotates the humerus in a way that aligns the posterior delt fibers more effectively with the line of pull. Try both. See which one gives you that "burn" faster.
Why You Can't Skip These
Rear delts are the "3D" muscle. If you want that rounded, cannonball shoulder look, you need them. Front delts get hammered by bench presses and overhead presses. Side delts get worked with lateral raises. But the rear delts are often the missing link.
Beyond aesthetics, it's a safety issue. If your front delts are significantly stronger than your rear delts, your humerus gets pulled forward in the socket. This leads to impingement, rotator cuff tears, and that "caveman" posture. Think of dumbbell reverse flys as your "prehab" work. They keep the joint balanced and stable.
Programming for Success
You don't need to do these every day. Twice a week is plenty.
Because the rear delt is a small muscle with a high percentage of slow-twitch fibers, it responds well to higher repetitions. Think 12 to 20 reps. Going for a 5-rep max on reverse flys is a recipe for a neck strain.
Try adding them at the end of your "Pull" day or your "Shoulder" day.
👉 See also: Energy Drinks and Diabetes: What Really Happens to Your Blood Sugar
- Set 1: 15 reps (warm-up, focus on the squeeze)
- Set 2: 12-15 reps (challenging weight, perfect form)
- Set 3: 12-15 reps (go until form starts to break)
- Set 4: Drop set. Do 10 reps with your working weight, then immediately grab a lighter pair and go to failure.
The Pinky Secret
Here is a weird tip that actually works: lead with your pinkies.
When you raise the dumbbells, think about tilting the weight slightly as if you're pouring out a pitcher of water. This subtle internal rotation can help some people "find" the rear delt more easily. It’s not for everyone—some find it bothers their rotator cuff—so move cautiously. But for many, it’s the "aha!" moment for mind-muscle connection.
Real-World Evidence
Take a look at the training programs of old-school legends like Vince Gironda. He was a huge proponent of high-volume rear delt work to create "width" from the back. Modern sports science backs this up. Dr. Mike Israetel of Renaissance Periodization often highlights that the rear delts can handle (and actually require) more volume than we typically give them because they recover quickly.
If you aren't seeing progress, look at your frequency. If you're only doing three sets a week, you're just maintaining. Bump it up to 10 sets a week spread over two sessions and watch what happens.
The Bottom Line on Rear Delt Training
Stop thinking of this as a power move. It’s a finesse move.
The dumbbell reverse fly is about tension, not tonnage. If you can't hold the weight at the top of the rep for a full second, you're going too heavy.
Focus on the stretch at the bottom and the hard contraction at the top. Keep your neck neutral—don't look up at the mirror, as that kinks your cervical spine. Look at a spot on the floor about four feet in front of you.
Actionable Steps to Take Now
- Record yourself. Side profile. Are you swinging? Is your back flat? You'll be surprised how different your form looks compared to how it feels.
- Lower the weight. Whatever you're using right now, drop it by 5 pounds and focus on a 3-second eccentric.
- Try the chest-supported version. If you've never done these on a bench, make it your primary rear-delt movement for the next four weeks.
- Mind-muscle connection. Before you even pick up a weight, do the motion with just your arms. Feel the muscle on the back of your shoulder tensing up. If you can't feel it without weight, you won't feel it with weight.
Get those rear delts working and the posture—and the "pop" in your shoulders—will follow.