Fitness Tips

Rear Delt Exercises Are Critical for Improving Your Posture—Here Are 6 To Try the Next Time You Hit the Mat

Zoe Weiner

Photo: Getty Images/Cavan Images
Your “rear delts” aren’t exactly a muscle group that are talked about as frequently as, say, your core and your glutes. But that doesn’t mean it isn’t just as important to keep them strong. They’re responsible for all of the pushing movements your upper body makes on a daily basis—whether that means pushing a stroller, opening a heavy door, or throwing a medicine ball—and they are key for helping you to maintain proper posture and avoid any slumping-induced back pain. “Their job is to extend, abduct, externally rotate and horizontally extend the humerus bone [upper arm bone] at the shoulder joint,” explains Juliet Kaska, a celebrity trainer and Vionic Innovations Lab expert.  In other words? You shouldn’t be ignoring them. This is why we rounded up six moves to help you ensure that rear delt exercises are a permanent part of your weekly fitness routine.

What are your rear delts?

Your deltoid muscle, which looks like a large triangle that was placed over your shoulder (the name “deltoid” actually came from the Greek letter “delta,” which is shaped like a triangle) is split into three different parts. There’s the anterior deltoid, which is at the front of your body, the intermediate deltoid, which is runs over the top of your shoulder joint, and the posterior or rear deltoid. “The rear delt acts as part of your back muscles and is located at the back of the shoulder,” explains Danyele Wilson, a U.S. trainer for the Tone and Sculpt fitness app. “The posterior fibers assist the back muscles to extend the shoulder, and rear delts help you maintain proper posture and act as a major stabilizer of the shoulder to help prevent back pain and shoulder dislocation.” These muscles are integral for helping you both in the gym, with moves like push-ups and chest presses, and off of the mat as you move through your everyday life. “Hunched shoulders mean our head has to come forward to compensate, leading to a troubling path that can result in chronic headaches, spinal problems, mental distress,” says Kaska.

Why rear delt exercises are important for strengthening your upper body and avoiding injury

Aside from making you look like the strong friend who can open a heavy door on a windy day, regularly doing rear delt exercises can help keep your posture and check… and ultimately help you avoid the back and shoulder pain that poor posture brings. When your rear deltoids are underdeveloped, explains Kaska, you tend to overcompensate with other muscles in your upper body, like your anterior deltoid and pectoral muscles. Because of this, your pectoral minor (aka the muscle between your armpit and your chest) gets short and tight, which further weakens your rear deltoids. “What all that really means, though, is that weak rear delts leads to an unfortunate domino effect for our posture and makes us more prone to injury,” she says.

Because of this, people can spend years thinking they’re working their upper body perfectly without realizing that they’re doing the moves incorrectly because of their shoulder alignment. The reason? They’ve been ignoring their rear deltoids. And eventually, this can lead to injury and discomfort. “Think of the rear delts as ensuring postural alignment for your shoulders,” says Kaska, adding that bad spinal posture (which many of us are guilty of having, especially in the Zoom era) is known to cause aches and pains throughout the body. “Similarly, if our shoulder is misaligned, which can happen if our rear delts are underdeveloped and their opposing and synergistic muscles become overused and strained, we become prone to shoulder and rotator cuff injuries as well as other issues that can take a long time to heal.”

How to strengthen your rear delts

Though your rear delt muscles are technically located in your shoulders, Kaska likes to train them on back day, instead of integrating them into your usual upper-body series. “To keep the whole area strong, I’d definitely pair the rear delts with any exercises that target the rotator cuff muscles,” she says. “It’s also great to incorporate the triceps, or the lat muscles, which also work synergistically with the rear delts.” Wilson suggests trying some compound lifts that target your chest and back (think: push-ups) since these types of moves will “simultaneously target the rear delts, as they are needed to stabilize such lifts,” she says.

Rear delt exercises to try

1. Reverse flies

“I love, love, love reverse flies—they are the quintessential rear delt activator,” says Kaska. “My favorite variations are to perform them lying on a bench prone (on your belly), or incline prone.” Simply lie on your belly with a weight in each hand, and activate your back to raise and lower them slowly off of the floor. “Make sure your core is equally engaged to prevent undue stress on the lower back, and a swing motion in the torso,” she adds.

2. Bent over reverse flies

Take reverse flies to your feet with this move, which works the same muscles from a standing position. Keeping your back flat and your knees loose, bend your upper body to a 45-degree angle and use your back muscles to “fly” your dumbbells out to the side, creating a “T” shape with your upper body. You’ll know you’re using the right muscles if you can feel your shoulders squeezing at the top of the move. No weights? No problem. You can also try this move with a resistance band.

3. Band or cable face pull

This move requires a little bit of setup, but it’s worth it. Wrap an exercise band around a pole (or, if you’re at home, a chair, banister, or door hinge) so that it’s the same height as your nose. Slowly pull the band toward your face, engaging through your shoulders and upper back, and work on keeping your arms parallel to your shoulders.

3. Wide grip inverted row

Find a bar (which you can easily re-create at home with a sturdy broomstick and two chairs) and lie down underneath it with your feet raised onto a chair or bench. Grab on with your hands positioned slightly wider than your chest, and engage your glutes and core as you pull your body toward the bar. Unlike your usual rows, which target your lats, this move will target some of the smaller, weaker muscles in your back like—you guessed it—your rear delts.

4. Upright rows

With this move, proper form is key—without it, you’ll wind up missing out on the rear delt benefits that it has to offer. Choose a set of medium-sized dumbbells, and stand with your feet shoulder-width apart, with the one in each hand. Pull your weights up to chest level, and be sure to keep your elbows under your wrists, shoulders relaxed, and core engaged.

6. Shoulder extensions

Combine your rear deltoid work with your go-to tricep exercise with this easy tweak to the traditional move. “Next time you’re doing tricep kickbacks, hold your arm straight at the top, then reach your arm even closer to the ceiling,” says Kaska. “Boom. You just kicked your rear delts into higher gear.”

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