The functional trainer rear delt fly targets your posterior deltoids using cable resistance to build stronger, more defined shoulders and upper back muscles.
This exercise helps fix rounded shoulders, improves posture, and balances out your chest training by strengthening the often-neglected back side of your shoulders.
What Makes the Rear Delt Fly Special on a Functional Trainer
Your rear delts get ignored way too often. You probably spend tons of time doing bench presses and shoulder presses. But when did you last focus on the back of your shoulders?
The functional trainer gives you smooth, constant tension throughout the entire movement. Unlike dumbbells that feel heavy at some angles and light at others, cables keep your muscles working hard from start to finish.
I found that many fitness experts recommend rear delt work as a game-changer for shoulder health. The American Council on Exercise points to posterior deltoid strengthening as key for balanced shoulder development.
Perfect Form Setup
Getting your setup right makes all the difference. Poor form turns this great exercise into a waste of time.
Cable Height and Position
Set both cable pulleys at chest height. Stand in the middle, about two feet back from the machine. You want enough distance so the cables don’t go slack when your arms are fully extended.
Grip and Hand Position
Cross the cables over each other. Grab the right handle with your left hand, and the left handle with your right hand. Use an overhand grip with your palms facing down.
Some people prefer using the cable ends without handles. This gives you more wrist freedom and feels more natural.
Body Stance
Plant your feet shoulder-width apart. Keep a slight bend in your knees. Pull your shoulder blades down and back. Think about standing tall and proud.
Step-by-Step Movement
Now comes the fun part. Here’s how to nail the movement every single time.
Starting Position
Extend your arms straight out in front of you. Keep a slight bend in your elbows throughout the entire movement. Your arms should look like you’re giving someone a big hug.
The Pull
Pull the handles back and out to your sides. Imagine you’re trying to touch your shoulder blades together. Lead with your pinkies, not your thumbs.
Stop when your arms are parallel to the floor. You should feel a strong squeeze between your shoulder blades.
The Return
Slowly let the handles come back to the starting position. Don’t just let the weight pull your arms forward. Control the negative part of the movement.
This controlled return builds just as much strength as the pulling phase.
Common Mistakes That Kill Your Results
I see these mistakes all the time at the gym. Avoid them and you’ll get better results faster.
Using Your Back Instead of Your Rear Delts
If you arch your back and pull with your lats, you’re missing the point. Keep your torso still. The movement should happen only at your shoulder joints.
Going Too Heavy Too Soon
Your rear delts are small muscles. They don’t need massive weight to grow. Start light and focus on feeling the right muscles work.
Rushing the Movement
Slow and controlled wins every time. Take two seconds to pull back, pause for one second, then take three seconds to return to start.
Weight and Rep Recommendations
Research from the National Academy of Sports Medicine suggests starting with lighter weights for isolation exercises like rear delt flies.
| Experience Level | Weight Range | Sets | Reps |
|---|---|---|---|
| Beginner | 5-15 lbs per side | 2-3 | 12-15 |
| Intermediate | 10-25 lbs per side | 3-4 | 10-12 |
| Advanced | 20-40 lbs per side | 4-5 | 8-12 |
Progressive Overload Tips
Add weight slowly. Increase by 2.5 to 5 pounds per side only when you can complete all sets with perfect form.
You can also progress by adding reps or extra sets before adding weight.
Muscles Worked and Benefits
This exercise hits more than just your rear delts. You get a nice compound effect.
Primary Muscles
- Posterior deltoids (back of shoulders)
- Rhomboids (between shoulder blades)
- Middle trapezius (upper back)
Secondary Muscles
- Lower trapezius
- Infraspinatus and teres minor (rotator cuff)
- Middle deltoids
Real-World Benefits
Strong rear delts help you maintain good posture at your desk job. They also improve your performance in rowing, swimming, and pulling movements.
The Mayo Clinic notes that balanced shoulder strength reduces injury risk during daily activities.
Variations to Keep Things Interesting
Once you master the basic movement, try these variations to challenge your muscles in new ways.
Single-Arm Rear Delt Fly
Work one arm at a time for better focus and core stability. Use your free hand to brace against the machine for support.
High-to-Low Rear Delt Fly
Set the pulleys above your head. Pull down and back at a 45-degree angle. This hits your rear delts from a different angle.
Seated Rear Delt Fly
Sit on a bench facing the machine. This removes any chance of using your legs or lower back to cheat the movement.
Programming Into Your Workout
Where does this exercise fit in your training plan? I found that most trainers recommend rear delt work on pull days or shoulder days.
Best Workout Placement
Do rear delt flies after your main compound movements but before small isolation exercises. Your rear delts assist in rows and pull-ups, so train them when they’re not pre-fatigued.
Frequency Recommendations
Train your rear delts 2-3 times per week. They recover quickly because they’re small muscles that don’t get worked too hard in daily life.
Troubleshooting Common Issues
Not feeling it in the right place? Here’s how to fix the most common problems.
Can’t Feel Your Rear Delts Working
Drop the weight and focus on the mind-muscle connection. Before you start, actually reach back and touch your rear delts. Now try to contract those exact muscles during the exercise.
Shoulder Pain During Movement
Stop immediately if you feel pain. Check your form and consider lowering the weight. If pain continues, talk to a healthcare professional.
Sometimes adjusting the cable height up or down by a few inches fixes shoulder discomfort.
Conclusion
The functional trainer rear delt fly deserves a spot in your routine. It builds stronger, healthier shoulders while fixing the muscle imbalances that come from too much pressing and not enough pulling. Start light, focus on perfect form, and be consistent. Your posture will thank you, your shoulders will feel better, and you’ll build the balanced physique you’re working toward. Remember that small muscles like your rear delts respond better to moderate weights and higher reps than trying to go heavy right away.
How often should I do rear delt flies on a functional trainer?
Train your rear delts 2-3 times per week with at least one day of rest between sessions. These smaller muscles recover faster than your chest or legs, but they still need time to repair and grow stronger.
What’s the difference between doing rear delt flies with cables versus dumbbells?
Cables provide constant tension throughout the entire range of motion, while dumbbells feel heaviest at the bottom and lightest at the top. Cables also let you adjust the angle more precisely and maintain better form since the resistance vector stays consistent.
Can I do rear delt flies every day?
Daily training isn’t recommended even for small muscles like rear delts. Your muscles grow during recovery periods, not during workouts. Stick to every other day or 3 times per week maximum for best results.
Why do my traps take over during rear delt flies?
This happens when you pull your shoulder blades up instead of back and together. Keep your shoulders down and away from your ears throughout the movement. Think about sliding your shoulder blades toward your back pockets, not toward your neck.
What weight should I start with for functional trainer rear delt flies?
Most beginners should start with 5-10 pounds per side, which might feel surprisingly light. Your rear delts are much smaller and weaker than your chest or front delts. Focus on perfect form and muscle activation before worrying about adding weight.
