Machine Rear Deltoid Fly

Machine rear deltoid fly (or machine reverse fly) is an excellent exercise for the rear part of the shoulder. Like cable exercise, the rear deltoid fly machine provides a uniform resistance throughout the range of movement. The machine also offers several technical adjustments to grip, trajectory, and range of motion to help isolate the posterior deltoid. The rear deltoid machine fly is a better alternative to bent over lateral raise because the stack based machine would provide continuous tension in a circular pathway. Also, the machine allows you to work with considerable weight without using your torso to cheat, as is often the case in the equivalent free weight exercise. It is also easier on your back, which does not have to hold you in the standing position.

Machine Rear Deltoid Fly Exercise Instructions

STARTING (INITIAL) POSITION: Sit with your chest against the pad on the machine (abs tight, chest up, back straight). Adjust the seat of the machine so that when you hold on the handles your hands are at shoulder height. Begin by holding on the horizontal handles (pronated grip – palms down), with your arms extended in front of you.

Machine Reverse Fly Exercise

MOVEMENT (EXECUTION): Open your arms backwards in a movement like a reverse hug keeping your elbows straight but not locked out. In other words, pull the handles out and back in an arc as far as possible (until your arms are in line with your back), contracting your rear delts. Keep your elbows high and arms roughly parallel to the floor during the movement. Hold and squeeze your shoulder blades together. Pause for two counts at the top of the movement, then return the weights slowly to the floor.

Machine Reverse Fly Key Points & Common Mistakes

Additional helpful hints on how to master machine rear deltoid flyes like a pro.

The seat of the machine should be adjusted to a height that allows the shoulders to be at the same level as the hands gripping the handle (or just little below shoulder level).
The elbow should be held up in line with shoulder & the wrist throughout the movement.
Using the horizontal handles with a pronated grip (palms down) is the best method of isolating the posterior deltoid because the shoulder is internally rotated.
Keep your arms slightly bent throughout the movement, with all of the motion occurring at the shoulder joint.
Keep your chin and rib cage lifted so that you are not tempted to lean forward in an attempt to push the handles further back.
Do not allow muscles to relax before the next repetition.
Common mistakes: incomplete movement and doing the exercise too fast/jerking on the weights.

Machine Rear Deltoid Fly Variations

One-Arm Machine Rear Deltoid Fly. If you do this exercise one arm at a time you can reduce the relative contribution from the trapezius and the scapular retractor muscles. This aids posterior deltoid isolation.
Alternate between a neutral (palms facing each other) and a pronated grip (palms facing the floor).
Pec-Deck Machine Rear Deltoid Fly. This is similar to the basic exercise, but using a pec-deck machine. Sit backwards on the machine with your chest resting against the seat back. Position your arms at a 90º angle to your body. Depending on the design of the machine, you may be able to rest your elbows against the pads designed to be used for the forearms in the chest exercise. Contract your rear deltoid (although this will always be a partial movement). You do not need to use the pec-deck if your gym has a purpose-designed machine for the rear deltoid. However, it should not be ignored if you want to work the rhomboids and neighboring muscles involved in short movements and the final part of drawing your shoulder blades together.

Muscles Engaged in Machine Rear Deltoid Fly

This exercise mainly engaged the posterior deltoid, infraspinatus, and teres minor and, at the end of the movement, when the shoulder blades squeeze together, the trapezius and rhomboids.

Main muscles: deltoid (rear), trapezius;
Secondary muscles: deltoid (middle), rhomboids, latissimus dorsi, teres major and minor, triceps;
Antagonists: deltoid (front), pectoral muscles, biceps;

Replacement Exercises

Closing Thoughts

The seated rear delt machine is a great exercise to use for variety in your shoulder training arsenal.

Maybe you will be surprised, but a good machine seems to be superior to both the pulley and dumbbells. The machine allows you to perform this rear deltoid exercise in seated position which is less precarious than when you are bent to 90-degrees. The leaning forward position is especially problematic with dumbbells when you are lifting heavy weights. The spine is recruited without a purpose, and the stomach gets compressed. When using a pulley, at least the arm that is not working can support the spine by pushing on the thigh.

In conclusion, this is a perfect posterior deltoid exercise for those who feel dizzy when bent over, or feel too much chest compression from having to lean on the incline bench, or who have lower back problems.