Why the Dumbbell Chest Fly Is a Must-Do Upper-Body Exercise

Use these expert tips to mix the dumbbell chest fly into your training program, and you'll become a seriously strong push-up pro in no time.

an exerciser demonstrating how to do a Chest Fly workout move
Photo: Jenna Brillhart

Given the emphasis on building powerful glutes and strong biceps within the online fitness community, you may be tempted to overlook a key muscle group in your upper body: the chest. But by skipping over the dumbbell chest fly (sometimes called the pec fly), among other chest-strengthening exercises, you may struggle to tackle other moves in your resistance training program or even stand slouch-free.

To help you introduce the dumbbell chest fly into your routine — and start scoring all its health benefits — Shape tapped two fitness pros to break down how to do the exercise with proper form. Plus, they share dumbbell chest fly variations so you can tweak the exercise for your needs. After reading their tips and details on the exercise's perks, you'll never skip chest day again.

How to Do a Dumbbell Chest Fly

A dumbbell chest fly or pec fly involves lying on the floor, holding two dumbbells above your chest, then slowly lowering your arms down to the floor at your sides. In turn, the dumbbell chest fly is an adduction movement — meaning it involves moving free weights toward the midline of your body — designed to strengthen, well, your chest, says Ash Wang, C.S.C.S., a certified strength and conditioning specialist. The move can either be performed on a bench or on the floor, as Rachel Mariotti, an NCSF-certified personal trainer in New York City, demonstrates below. 

A. Lie faceup on the floor with a dumbbell in each hand resting on top of chest, knees bent at 45-degree angles with toes lifted off the floor. Extend arms straight above center of chest to raise dumbbells toward the ceiling, palms facing toward one another. Optional: Gently lift upper shoulders and neck off the ground for further core activation.

B. Keeping elbows slightly bent, inhale and slowly lower both arms out to the sides while shoulder blades naturally retract. Pause when dumbbells reach shoulder height.

C. Exhale and squeeze through chest to pull dumbbells back together above chest to return to the starting position.

The Key Dumbbell Chest Fly Benefits

By mixing the chest fly into your upper-body workout routine, you'll see improvements in your strength, posture, and even push-ups. Here, the pros break it down.

Maximizes Chest Growth

Folks who are looking to build up serious chest strength — whether it be for a powerlifting competition or a physically demanding job — will typically want to prioritize the barbell chest press, an exercise that greatly activates the pectoralis major (the largest chest muscle that lies underneath the breast tissue), the anterior deltoid (the front head of your shoulder muscle), and the triceps brachii (the muscle on the backside of your upper arm), according to the Journal of Sports Science & Medicine. That said, the dumbbell chest fly can play an important role in helping you hit that chest strength goal, says Wang. “The purpose of a chest fly is for chest adduction, and that’s not really something you can get from your standard pressing motions,” she explains. “So you can think of the chest fly as accessory work if you are focused on maximizing chest growth,” notes Wang.

In other words, the chest fly complements the bench press, and it can help strengthen the smaller, supporting muscles (such as the biceps) so you can push through plateaus during the latter exercise. 

Improves Posture

While it’s particularly important to strengthen your back muscles to keep your posture on point, focusing on your chest can also help you stay slouch-free. "The fly is great because it's a nice chest opener and teaches scapular retraction," says Joey Thurman, C.P.T., C.S.C.S., a fitness and nutrition expert and author of 365 Health and Fitness Hacks That Could Save Your Life. ICYDK, scapular retraction basically means the ability to pinch the shoulder blades together — an action that's super important for combating poor posture from sitting hunched over a desk or cell phone all day.

Helps You Master Push-Ups

If you’re aspiring to bang out 10 push-ups in a row with excellent form — or at least do a few without any modifications — the chest fly can help you get there. Remember: Push-ups primarily call upon your pectoralis major and anterior deltoid, research shows. Since the chest fly helps build strength in those same muscle groups, practicing it on the reg can translate to higher-quality push-ups, says Mariotti. 

Dumbbell Pec Fly Muscles Worked

As previously mentioned, the chest fly will largely call on your pectoral muscles, as well as your anterior deltoids. But your latissimus dorsi (which helps you extend and rotate your shoulders and arms) also help you complete the movement, says Wang. Your biceps also come into play with each rep, as they may help stabilize and help your elbow maintain a constant angle, according to the Journal of Sports Science & Medicine study.

Dumbbell Chest Fly Variations

If you give the dumbbell chest fly a shot and find it doesn’t sync with your fitness level or needs, swap the move with one of these scaled-down or leveled-up variations.

Modification: Wide Dumbbell Chest Press

To prep your body for a chest fly, start off with a wide dumbbell chest press first, suggests Mariotti. Thanks to your bent elbows, you’ll have more leverage as you press your arms toward the ceiling, but due to the wider stance, the dumbbells will be positioned farther from your center and thus offer a greater stability challenge, she explains. Simply put, this mash-up of a chest fly and chest press is a perfect prerequisite before you move on to the real deal, says Mariotti.

Progression: Hollow Body Chest Fly

To amp up the core challenge of a dumbbell chest fly, perform the move in a hollow body hold, suggests Mariotti. “Instead of [placing] your feet down on the floor, you’ll float them up and position your body to be hollow like a banana,” she explains. In this position, you’ll have less stability, and your core will have to work extra hard to keep you balanced, she notes.

Common Dumbbell Chest Fly Mistakes

One of the biggest form mistakes Wang sees folks make when doing a dumbbell chest fly is allowing their scapula (aka shoulder blades) to slide forward at the top of the movement. “It almost looks like their upper back is rounded,” notes Wang. “When you do that, it releases tension at the top and then the pectoral fibers don't get the desired contraction,” she explains. To ensure the exercise is as effective as possible, remember to keep your shoulder blades retracted and flat on the floor as you bring the dumbbells back toward your midline, she suggests. 

If you’re performing the move on a bench, be careful of lowering the dumbbells too close to the ground at your sides, particularly if you’re using heavy weights, says Wang. Doing so ups the risk of a shoulder injury, especially if you’re lacking adequate shoulder mobility, she explains. “If you want to eliminate that possibility, I would just perform them on the floor,” says Wang. “That way the floor is gonna stop the range of motion.” Regardless of where you’re doing your reps, remember to keep your wrists neutral, as the pressure of the weights may cause irritation if the joint is bent, says Mariotti. 

How to Add the Dumbbell Chest Fly to Your Routine

While everyone should consider incorporating the chest fly into their training regimen thanks to those aforementioned benefits, bodybuilders, in particular, should mix it in, as it can help them meet their muscle growth goals, recommends Wang. If you give the dumbbell chest fly a shot and notice any aches or pains in your shoulders, make sure to reach out to your health-care provider to chat over your concerns and ensure the move won’t increase your risk of injury, she adds. 

Ready to get started? Try doing four sets of eight to 12 reps, taking adequate rest breaks in between to ensure proper recovery, suggests Wang. When choosing your weight, “go lighter rather than heavier,” adds Mariotti. “The distance away from your midline is greater, so you're not going to handle as much weight [as in other exercises],” she explains. And as with any exercise, aim to perform the dumbbell chest fly at least twice a week in order to encourage muscle growth, says Wang. Follow those recommendations, and your push-ups and posture are sure to improve.

Photography and art: Jenna Brillhart
Model and fitness expert: Rachel Mariotti
Wardrobe: SET Active

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