What is a Rear Deltoid Fly? (A guide for building shoulders)

What is a rear deltoid fly?

What is a rear deltoid fly?

The rear deltoid fly is a resistance exercise that targets the posterior deltoid muscle at the back of the shoulder. It can be performed with dumbbells, cables, or on a rear deltoid fly machine. 

Developed rear deltoid muscles give the shoulders a rounder look, add width to your frame, and increase strength for your pulling exercises (rows, deadlifts etc.).

Rear delt fly muscles targeted

Which muscles are targeted with a rear delt fly?

The focus of the rear delt fly is to add strength and size to the rear deltoid muscle. A correctly performed rear delt fly will aim most of the resistance at this muscle. Other muscles are secondary targets or assisters to the rear delt fly. 

How do I do a dumbbell rear delt fly
The lateral deltoids and the rhomboids are the major secondary muscles targeted when in the fully bent-over position. If you are not fully bent over, you will be bringing the traps into play. 

Benefits of a rear deltoid fly.

There are a few benefits to adding a rear deltoid fly movement to your shoulder workout. If you are a bodybuilder, the aim is hypertrophy. 

By performing sets of 15-18 reps of the rear delt fly, you will be adding mass to your rear delts giving a better aesthetic to your shoulders. Adding mass to the posterior delts will push your lateral delts out, giving extra width to the shoulders and helping to define your upper arm muscles. 

If strength is your goal, adding the rear delt fly to your routine will give you extra stability for your rowing and pulling movements. All-round, stronger shoulders will also give added strength to your bench press and overhead press movements. 

There is also the issue of posture. Developing your chest and anterior delts with pressing movements without performing regular rows and back exercises can lead to a 'hunched' posture. 

This is especially prevalent if you spend most of your day sitting at a desk. Developing the rear delts and upper back helps you to straighten the spine with a better posture. 

How do I perform a rear delt fly?

The rear delt fly is a simple, uncomplicated exercise. There are a few different methods which use a variety of equipment, but they all do the same thing. Here we will look at some of these methods...

The dumbbells are the preferred tools for performing the rear delt fly among the majority of bodybuilders. If you have a rack of dumbbells and a mirror, you can scale the weights up or down while keeping an eye on good form. 

Dumbbell rear delt fly exercise

  1. Select your dumbbells, start with a light weight, and scale up if you need to. 
  2. Stand with your feet at shoulder width and the dumbbells down by your side.
  3. Bend your knees slightly for stability. Bend over at the hips keeping your spine straight to around 90 degrees.
  4. Raise the dumbbells at each side in a 'fly' movement. Keep your arms slightly bent and make sure that you are getting a good connection with the rear delts.
You can perform this movement while sitting on a dumbbell bench and leaning as far forward as possible or lying face down on a dumbbell bench and using it for support. 

Some people find it easier to stand, lean forward and rest their forehead on the top of an inclined dumbbell bench. This takes some of the pressure off the lower back stabilisers and adds extra support. 

Another advantage of using a bench is that it is harder to 'cheat' the movement by swinging the weights and jerking at the knees. 

If you find that you are not getting a great connection with your rear delts, try changing your grip slightly by keeping your palms facing behind you instead of towards each other. 

Cable rear deltoid fly.

Cables are a great alternative to dumbbells for the rear delt fly movement. They add resistance at a slightly different section of the movement due to the nature in which the cable is pulled. 

Even if you regularly perform a rear delt fly in your routine with dumbbells, try switching to cables occasionally to shock the muscle. This keeps it guessing and, working it from a slightly different angle, can help you add extra mass. 

Cable rear delt fly
The posture and movement is essentially the same as a bent-over dumbbell fly. Using flexible stirrup attachments, you can rotate your wrists to make sure that you are getting the best possible connection with the posterior deltoid muscle. 

If you only have a single cable machine, you can still perform the movement by focusing on one arm at a time.

Upright rear deltoid cable fly.

If your gym has a twin cable machine, the upright rear delt cable fly is another great option. It is the same movement as the bent over rear delt fly, but instead of setting your pins at the bottom, they are placed in a high position, and you are stood in an upright position. 
Standing cable rear delt fly
This exercise can be performed with stirrup attachments, single rope attachments or even just by holding the ball stop at the end of the cable. Using a higher setting will target the lower traps and rhomboids as secondary muscles, whereas a lower setting will activate the upper traps. 

Rear delt machine fly.

You may be lucky enough to have a dedicated rear delt fly machine at your gym or a pec dec that converts to a rear delt fly machine. The main advantage of using a machine is the stability of the movement, and easy weight selection for drop sets, etc.

rear delt machine fly

Using a dedicated machine allows you to take the strain away from core stabilising muscles and focus on the target muscles. Adjusting the seat height and grip allows you to make sure that you are getting the best connection possible with the rear delts. 

Rear deltoid fly machines come in all shapes and sizes. Some are seated, some are standing, and some are forward-laying machines, but they all target the same muscles. 

If you do not have a dedicated machine for a rear delt fly, you can improvise and use a lateral fly machine. Simply stand in front of a lateral fly machine, bend over with a straight spine, and rest your forehead on the top of the seat. 

You may need to use a pad or cushion for this. Tuck the back of your forearms under the fly pads and begin to perform a rear deltoid fly movement. 

There are other rear delt exercises that can be performed with kettlebells, bands or dumbbells, but the above movements are the most popular and will usually give you the best result. 

What is a rear deltoid fly alternative?.

Face pull

Upright row

Rear delt row


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