rear delt fly
Strength Training

Rear Delt Fly 101: Exercise Guide For Huge Deltoids

Complete shoulder development requires working on each of the three heads of the deltoid muscle; anterior, medial, and posterior. Most guys do a decent job of building muscle in the anterior (front) and medial (side) delts but not so much with the posterior or rear shoulder muscles.

One exercise that specifically targets the posterior deltoids is the rear deltoid fly. If your goal is to develop 3-D deltoids, then you need to include this exercise in your shoulder routine.

Rear Deltoid Fly Benefits

1. Targets the Rear Deltoids

The dumbbell rear deltoid fly allows you to specifically target your rear shoulder muscles. By including this exercise in your routine, you will be able to achieve full, rounded shoulder development.

2. Enhances Upper Body Detail

This is an isolation-type exercise that requires lighter weight to build lean muscle mass in a small muscle group. When you are able to bring out your rear delt muscles, you will be adding a level of deltoid muscle definition to your physique that is visually impressive.

3. Better Posture

Working the posterior delts with a reverse fly will also lead to improved posture. As a result of our computer-based lifestyles, many people end up with a hunched-over posture that leads to hunched shoulders. The rear delt flye will help to realign the shoulder joint and correct bad posture.

By performing this dumbbell rear deltoid shoulder exercise, you will also be able to avoid muscle imbalances and the resultant muscle weaknesses that can lead to injury.  

Muscles Worked

rear delt fly muscles worked 1

The rear deltoid flye targets the posterior head of the deltoid muscle. It originates on the top of the shoulder blade and inserts on the top of the humerus. This insertion point is alongside that of the other two deltoid muscle heads.

Related Post: Best Rear Deltoid Exercises for Toned Shoulders

The main job of the posterior deltoid is to bring your humerus bone back posteriorly towards its origin. It also helps to externally rotate the humerus. The posterior deltoid muscle fibers go in a diagonal direction down across the rear part of the shoulder.

Related Post:  The Ultimate Guide to The Supinated Lat Pulldown

The whole idea of this exercise is to target and isolate the posterior deltoid muscle head. So, when done properly, it does not involve any secondary muscle groups. 

Related Post: 10 Middle Deltoid Exercises For A Great Shoulder Workout

How to Perform the Rear Deltoid Fly

  1. Stand with your feet hip-width apart and a pair of light dumbbells in your hands.
  2. Assume a hip hinge position to bring your torso down to a position that is almost parallel to the floor.
  3. Hang your hands down in from of your body with your arms slightly bent but locked in position.
  4. Move your arm out to the sides of your body and up to your shoulder level.
  5. Lower under control and repeat.


  • Pinch your shoulder blades together in the top contracted position.
  • Do not swing your torso up and down as you perform this exercise; the only movement should come through the shoulder joint.
  • Do not straighten your arms; keep them slightly bent throughout the exercise. 
  • Be sure to keep the weight light enough to be manageable. If you go too heavy, you will be forced to bring your larger lateral and anterior deltoid muscles into the exercise. Remember that the posterior delt is the weakest and the front delt is the strongest muscle in the shoulders; leave the heavy weight for your front delt work.
  • Be sure to move through a full range of motion. 


There are a number of variations of the traditional dumbbell rear deltoid fly which make useful additions to a well-rounded routine. Here are five variations you should rotate in and out of your program.

Lying Supine Cable Crossover

  1. Place a bench in the middle of a double pulley cable machine and set the pulleys at the level of your head.
  2. Hold the handles in a crossover manner (left hand grabbing the right cable and vice versa) and lie on the bench on your back.
  3. From a start position with your arms directly above your chest and elbows slightly bent.
  4. Pivot from the shoulder joint to bring your arms out and down to the level of your shoulders.
  5. Reverse under control and repeat.

Training Tip: Squeeze the shoulder blades in toward each other in the bottom contracted position.

Cable Machine Reverse Fly

  1. Sit on a reverse pec deck machine facing in toward the machine. Place your elbows against the elbow pads.
  2. Maintaining an upright posture, push your elbows back and together as you pinch your shoulder blades together.
  3. Reverse and repeat.

Training Tip: There are a number of rear delt machine configurations in terms of arms placement. However, the basic movement is the same; bringing the elbows back and squeezing the shoulder blades together.

Incline Lying Rear DB Raises

  1. Set the angle on an adjustable exercise bench to 30 degrees. Grab a light set of dumbbells and on the bench, facing the floor so that your head is hanging over the top of the bench and your arms are hanging down.
  2. Maintain a slight bend in your elbows as you bring the weights to the side and up to shoulder level. Pinch your shoulder blades together at the top of the exercise.
  3. Lower under control and repeat.

Training Tip: Keep your feet firmly planted on the floor throughout this exercise. Keep your arms locked in a slight bend position, with the only movement coming through the shoulders. You should move through an arching motion. 

Cables Rear Deltoid Fly

  1. Set the cables on a double pulley machine at shoulder level and remove the handles from the ends of the cables.
  2. Grab the cable ends in a crossover manner and stand in the middle of the machine facing it about six feet back from the weight stacks.
  3. From a starting position with the cables in front of your chest and arms straight, bring your arms downward and diagonally out to full arm extension. Revere and repeat.

Training Tip: You may wish to wear gloves on this exercise as you will be directly gripping the cables. 

Side-Lying Delt Raise

  1. Take hold of a light weight and get down on the floor on your side with your legs stacked upon each other. Hold the dumbbell in your top hand and extend that arm directly out in front of your body.
  2. Bring your straightened arm up at a slight diagonal until it is above your body.  Reverse the movement under control. 

Training Tip: Your lower arm should be resting on the floor out diagonally to your head.

Final Thoughts

The rear delt fly is an essential movement if your goal is to develop full, rounded, and complete shoulders. As shown in this article, there are a number of variations and exercise options that you should rotate in and out of your routine.

Be sure to keep the weight relatively so that you can maintain proper form. Your rep range should be between 12-25 per set. Do a total of six sets for your rear deltoids. 

Frequently Asked Questions

Are reverse flys for back or shoulders?

Reverse flys are a shoulder exercise that specifically targets the posterior deltoid muscle head, so when performed properly, they should target the shoulders.

Should you do shoulders with back?

There is no reason why shouldn’t work shoulders with your back. Be sure, however, to work the larger back muscles first so that you don’t exhaust the shoulders before you begin working them. 

Are rear delt raises good?

The rear delt raise is a good exercise to target the posterior delts. However, the standing bent over position puts quite a load on the erector spinae muscles of the lower back. Doing the incline bench and cable versions of the exercise takes the strain off the lower back. 

Steve Theunissen

Steve Theunissen is a former gym owner and personal trainer based in Tauranga, New Zealand. He is the author of six hardcopy books and more than a hundred ebooks on the topics of bodybuilding, fitness, and fat loss.

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