Most people who train shoulders spend nearly all their time on the front and side delts — presses, raises, the muscles you can see in the mirror. The rear delts get skipped almost by default. But this small, often-ignored muscle group has a real impact on how your upper body looks, how your shoulders move, and how well you hold your posture.
The rear delt machine is one of the simplest and safest ways to bring this muscle group into your training. It gives you a controlled, guided movement that isolates the posterior deltoids properly, which makes it a worthwhile addition to almost any shoulder routine.
Why the Rear Delts Matter
The rear delts, or posterior deltoids, do a lot of quiet work — stabilising the shoulder, supporting the upper back, and helping keep your posture upright. Neglect them for long enough and your shoulders start to round forward, which throws off the whole look of your upper body. Training this area regularly is one of the more underrated ways to build broader, more balanced-looking shoulders while also strengthening your upper back.
Getting Started with the Rear Delt Machine
Good form matters more than heavy weight here. Set the seat height so your shoulders line up with the handles and your chest stays upright against the pad. Grip the handles firmly and pull through a slow, controlled arc, squeezing your shoulder blades together at the top of the movement. The goal is to feel the contraction, not to move the biggest weight stack you can manage.
If you’re new to the exercise, start light. Getting the movement pattern right first will do more for your shoulders — and reduce your injury risk — than adding weight too early.
Pairing Rear Delt Work with Chest Training
A lot of lifters focus heavily on chest, particularly the lower chest, while still wanting balanced, well-rounded shoulders. The two aren’t in competition — they work well together. Mixing rear delt fly work with lower-pec exercises like incline or decline presses helps build an upper body that looks proportional from every angle, not just from the front.
Tips for Getting the Most Out of It
Consistency is what makes this exercise pay off. A few things worth keeping in mind:
- Train the rear delts alongside your core and back work to build overall shoulder stability, which makes other compound lifts safer too.
- Focus on control over load — a slower, deliberate movement recruits the rear delts far better than a fast, heavy one.
- Stick with it. People who train this area consistently tend to notice better posture and shoulder mobility fairly quickly.
Bringing It Into Your Routine
A balanced shoulder session usually starts with compound lifts to get the whole shoulder working, then moves into targeted isolation work like the rear delt fly machine. Round it out with a pressing movement — decline bench press is a solid option — to keep your angles even across the front, side, and rear of the shoulder. Small, consistent adjustments to form tend to add up to the biggest long-term gains.
Conclusion
If you want stronger, more balanced shoulders, the rear delt machine deserves a permanent spot in your routine. It targets a muscle group that’s easy to neglect and pays you back with better posture, more stable shoulders, and a more proportioned upper body. If you’d like guidance on technique or want a program built around your goals, our coaches at Alltone Fitness are happy to help.
FAQs
What muscles does the rear delt machine target? Mainly the posterior deltoids, along with supporting work for the rhomboids, traps, and other upper back muscles — making it a solid all-round upper-back and shoulder exercise.
How many sets of rear delt exercises should I do per week? Most people do well with around 9 to 12 sets per week, spread across two or three sessions. Adjust based on your fitness level and how quickly you recover.
Is the rear delt machine better than dumbbells for the shoulders? Neither is strictly “better” — they suit different needs. The machine gives you a controlled, isolated movement that’s great for beginners or for really honing in on the rear delts. Dumbbells allow more freedom of movement and build functional strength. Many people benefit from using both.
Can training rear delts improve posture? Yes. Strengthening the rear delts helps pull the shoulders back and stabilises the upper body, which can meaningfully reduce the tendency toward rounded shoulders over time.