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September 06, 2022 8 min read

You will find pec deck machines in most gyms. However, it is a piece of equipment that gets only half the credit it deserves, because you can give your rear deltoids an outstanding shoulder workout by reversing your position on the pec deck machine, facing the weights.

The reverse pec deck machine offers similar benefits to working out with pec deck alternatives like a cable machine, cable crossovers, or doing dumbbell bent-over raises, with additional benefits.

The muscles that benefit from the horizontal flyes that define the machine depend on your position while using it. As a reverse pec deck machine, you’ll target the back and rear delts, or the chest muscles during the standard position on the pec deck machine (chest fly). The range of motion looks similar to a lateral raise, and they do have many things in common, including which muscle groups they target.


Before you begin your routine on the reverse pec-deck, there are two important settings to check. They involve the seat height and the position of the handles.

Typically, you would want the seat set at a height that allows your hands to be in line with your shoulders and elbows when you are seated facing the weights.

When using the pec deck machine for reverse peck decks, remember:

  1. Set the handles as far back as possible. Unlike some other gym equipment where you place your hands at shoulder width, the reverse pec-deck requires the handles positioned so that they almost touch each other. In that position, the handles will provide a full range of motion by creating a deep stretch of the rear delts.
  2. Set the height of the seat to allow your hands to be at shoulder height when you grip the handle. This allows abduct movements of the arm and targets the rear delts.

This NIH study shows that activation of the posterior delt and infraspinatus are significantly greater with a neutral grip when using the reverse fly machine.


Once the machine is set up to the right dimensions, take in the following starting position.

Sit or stand facing the rear of the reverse pec deck machine with your legs spread apart enough to allow you to grip the handles with a slight bend at the elbows and your arms parallel to the floor.

Sit upright with your spine neck and head perfectly lined up and your abdominals against the backboard.

  1. When ready begin extending your arms laterally, away from the body. Continue that movement until they are almost aligned with your back. You must feel the contraction in your upper as your shoulder blades glide closer together.
  2. Take care not to allow your arms to travel past your back. The muscles you want to contract are the lateral muscles of the back, such as the rear delts and infraspinatus. If you extend your arms back too far, the rhomboids and other medial back muscles that draw the shoulder blades closer to the spine will benefit instead.
  3. Hold the extended position for a second or two, before slowly returning the weight back to the starting position. Keep a controlled pace, allowing the muscles in your upper back to stretch as you return the handles to your midline.
  4. To keep constant tension on the muscles throughout the entire set, do not allow the weight to completely rest at the starting position
  5. Repeat this process for reps.

Be careful to keep your core engaged and in the same position throughout. Do not thrust your head and chest forward to gain an extra inch of pull.


The rear delts are reasonably small muscles that are often disregarded because they are not as obvious.

The reverse pec-deck is an isolated exercise designed to work best with lighter weights and higher reps instead of heavier weights and lower reps.

It is best to select a weight that allows you to perform the reverse pec deck maintaining perfect form for 10-15 repetitions. If you make this the last exercise in your workout routine, you can go all out to create a proper rear-delt burn.

We suggest the following set and rep scheme:

1st set – 15 reps (30-second rest)

2nd set – (increase the weight slightly) 12 reps (30-second rest)

3rd set – as many reps as you can manage


Thereverse pec deck fly focuses on your posterior deltoids and your upper back muscles. This reverse fly exercise isolates the rear delts, or posterior deltoids while incorporating the lats, traps, and rhomboids as muscle synergists.

There are three deltoid muscles, responsible for extension, horizontal abduction, and external rotation movements of the shoulder joint. The reverse action to stretch the muscle involves flexion, horizontal adduction, and internal rotation of the shoulder joint.


Although there are three deltoid muscles, only the rear delt is targeted in the reverse pec deck workout. Here’s how they work.

Deltoid Muscles – Image from Shutterstock

Anterior or Front Delts  –A triangular-shaped muscle with one end attached to the outer third of the clavicle and the other end to the tuberosity of the arm. Its fibers run in a slanted fashion from the clavicle bone down to the biceps.

Medial or Side Delts  –Originates at the small projection on the scapula bone, known as the acromion process. It travels down to the same insertion point at the top of the arm as the front delt. 

Posterior or Rear Delts  –It is an oblong-shaped muscle that sits at the back of your shoulder. It originates on the scapula’s outer spine and comes down and around to feed into the same insertion point on the upper arm as the other two deltoid heads. Therefore, the fibers run down and across from the traps to the upper arm.

A key function of the rear delt is assisting the rotator cuff’s external rotation movement.


The rhomboids are two bilateral superficial muscles, the minor and major rhomboids on your upper back. They retract, elevate and rotate your scapula.

Strengthening your rhomboid muscles along with the rear delt assures a healthy posture. Furthermore, they activate muscle growth that enables you to lift more weight. Additionally, they help to avoid compensation issues and prevent injuries.


The trapezius muscle runs from the base of your neck, around your shoulder, and extends to your middle back. It helps you move your shoulders, arms, head, neck, and torso. It also stabilizes your spine to improve your posture.

For daily movements like lifting, reaching, and sitting, you need toned and strong traps. When you do your reverse pec deck machine workout, your taps control your scapulae when you lift your arms during the reverse pec deck fly range of motions.


Shoulder muscles – Image from Shutterstock

Neglecting the rear delts is not unusual. Many weight trainers and bodybuilders dedicate most of their time to building muscles like the front and side delts you can see. The rear delts are deep set, and not superficial enough to contribute to aesthetics.

However, neglecting them will create an imbalance in the strength and development of your shoulders.

They play a significant role in the overall broad-shoulder look, and if the rear delts are developed they make the other delts look thicker, not to mention the benefits to your posture.

The best way to work the rear delt is with transverse extensions that extend the arms back behind the body in the transverse plane. This movement allows for maximum shortening of the rear delt muscle. The reverse pec deck is an exercise that does this effectively.


  1. Using Momentum – If you fail to pause at the start and end of each movement, your motion will soon be no more than momentum, sidelining the muscles you want to work. You might be able to do double the recommended number of reps, but if they are momentum-driven, you will deny the targeted muscles maximum stimulation.
  2. Weight overload – The deep-set rear delts are hard for most people to contract, even with lighter weights. When the reverse pec-deck is loaded with too much weight, your other, stronger back muscles may take over. When that happens, you might want to load even more weight because it seems too easy. However, this is not an upper-body exercise hack. If you load more weight, it won’t increase the demand on the targeted muscle, but rather increases the demand on the larger muscles best suited to take on the stress.
  3. Incorrect set-up  –Setting up the reverse pec deck machine according to your body size and strength is crucial for optimizing the workout of your rear deltoids.


The reverse pec-deck machine is designed as an isolated machine exercise for targeting the rear deltoid muscles, offering several benefits.

 Woman’s Strong Shoulders – Image from Shutterstock


By training your posterior deltoids, the reverse pec deck machine develops your shoulder muscles.  

Strong shoulders play an important role in a range of workouts.

Simultaneous benefits of stronger shoulder muscles include improved effectiveness in complex exercises like the barbell bench press, deadlift, and overhead press.


TheNational Health and Nutrition Examination Survey of about 5,900 adults as the basis for their analysis determined that nearly 26% of the surveyed American adults reported sitting for more than eight hours per day, while nearly 45% said they were inactive. The researchers discovered similar patterns for both women and men.

Long periods of sitting, combined with muscle weakness, typically cause people to hunch over and round their shoulders. Fortunately, one of the best workouts for improving posture is the reverse pec deck machine.

Furthermore, if you have back pain and are continually slouching, the rear delt fly machine might help you cure this problem by tightening your rear delts. However, discuss this with your physician or physical therapist before you do.


The reverse pec deck machine provides significantly more stability than free-weight exercises like the bent-over reverse fly using dumbbells.

Using the reverse pec deck machine, the stress on your lower back is significantly less, and your core doesn’t have to work as hard to keep your torso stable. You also don’t have to worry about your hands’ path because the machine limits your range of action.

As a result, you can focus entirely on strengthening your rear delts without risking injuries. This choice is ideal for strength builders with histories of shoulder problems, and it is even ideal for beginners.


The posterior deltoids support the shoulder joints, and using the reverse pec deck machine for shoulder exercises to improve shoulder balance improves good form and posture.


Those who favor workout routines focusing on specific muscles or muscle groups each day will likely find the reverse pec deck machine ideal.

The reverse pec deck is an excellent machine for shoulder and back exercises that allow you to target and grow the rear deltoids specifically. 

With an axe rise, using pure horizontal abduction, it means the rear delts do the majority of the work pulling your arms backward.


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