reckonerSeated reverse dumbbell fly
Sit on the end of a bench, fold forward until your chest is near your thighs and lift the dumbbells out to the sides. Sitting removes the need to hold a bent over position on your feet, so the set is about the back of the shoulder and the upper back, which are the muscles a reverse fly is aimed at1.
Chest to thighs, squeeze the blades.
- Pattern
- Shoulder isolation
- Trains
- Rear delts, upper back
- Kit
- Dumbbell, bench
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 12 to 15 reps at RPE 8
- Progression step
- 1 kg once the top of the range is clean
- Skill
- Some technique
- Recovery cost
- Very low
Muscles worked
How to do it
Sit at the end of the bench and fold forward
Sit near the end of the bench with your feet flat and lean forward until your chest is near your thighs. Let the dumbbells hang below you with your palms facing each other.
Keep a soft bend in the elbows
Hold the same small bend through the whole rep. If the elbows bend more as the set gets hard, you are rowing the weights.
Squeeze the shoulder blades and lift out to the sides
Lift the dumbbells out to the sides by squeezing your shoulder blades together, and stop when the weights are level with your back. Keep the chest near the thighs through the whole rep.
Lower slowly to a long arm
Let the dumbbells come back until the arms hang long, and do not rest them against your legs between reps. Control the way down.
What goes wrong
Sitting up to heave the weights
Lifting the chest from the thighs gets the dumbbells moving and feels like a stronger rep. The torso made the first part of the movement, so the arms made less of it than the weight says.
Rowing instead of fly
Bending the elbows more as it gets heavy brings the dumbbells toward the hips. That is a different movement and a different group of muscles.
Shrugging toward the ears
The upper trapezius is already a measured helper in a reverse fly1. Lifting the shoulders hands it more of the job than helping.
How Reckoner progresses this lift
Six weeks of this lift, run through the real engine. Nothing below was typed in: the prescription, the decision and the sentence beside it all come from the same code that writes your week.
| Week | Prescribed | What it did |
|---|---|---|
| 1 | 3 x 12 | More reps 12 → 13 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 2 | 3 x 13 | More reps 13 → 14 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 3 | 3 x 14 | More reps 14 → 15 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 4 | 3 x 15 | Load up — → 1 kgYou hit the top of the range with three reps left in the tank (RPE 7), so the dumbbell weight goes up 1 kg to 1 kg. The weight went up, so the reps come down to twelve. You are now working 12 to 15. |
| 5 | 3 x 12 at 1 kg | Deload 40% of sets offFive weeks of building, then one week lighter. About 40% of the sets come off. The load holds and your reps stay where you earned them, so you keep the strength and lose the fatigue. |
| 6 | 2 x 12 at 1 kg | More reps 12 → 13 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. The lighter week is over, so this is back to three sets. |
Real engine output, not an illustration. Every row was produced by running the engine itself when this page was generated.
The full rule, and why the reps move before the load does, is in how Reckoner decides to add weight.
Questions people ask
Which muscles does it work?
In a study of 29 men and women doing reverse flyes with dumbbells and bands, the posterior deltoid was the muscle the exercise is aimed at, with the middle deltoid and the upper trapezius measured as helpers1. In a separate study of 30 healthy people across ten exercises, shoulder horizontal extension with the arm turned outward gave the highest activity in the middle trapezius2. That was with the arm turned outward, which is not the palms facing grip used here, so it says something about the upper back's part in a reverse fly and does not prescribe a grip.
Dumbbells or the machine?
Neither is better for muscle size. A meta-analysis of thirteen studies found no difference between free weight and machine training for hypertrophy3. A machine gives you a chest pad and a path, and dumbbells give you a free path and, in the library, smaller steps between weights than a stack. Pick the one you can set up correctly.
Will Reckoner put this lift in my plan?
Not by itself, and on purpose. The engine never places this lift for you: you reach it by choosing it in a swap or in the movement picker. It sits in the same swap group as the machine rear delt fly, so one can stand in for the other, and a lane you have put it on keeps it.
Similar movements
Reckoner eases the load first when this lift stalls, and offers one of these only if it stalls again after that. A lift already as light as your kit goes has no load left to ease, so the offer comes straight away. Each of them has a page.
Sources
- Bergquist and colleagues, Journal of Human Kinetics, 2018. Muscle activity in upper-body single-joint resistance exercises with elastic resistance bands vs. free weights 29 men and women doing flyes and reverse flyes with bands and dumbbells, with the posterior deltoid as the muscle the reverse fly is aimed at and the middle deltoid and upper trapezius measured as ancillary muscles
- Ekstrom and colleagues, Journal of Orthopaedic and Sports Physical Therapy, 2003. Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles 30 healthy people across ten exercises, with shoulder horizontal extension with external rotation among the two highest for the middle trapezius. This is a 2003 study and the standard reference on the question
- Haugen and colleagues, BMC Sports Science, Medicine and Rehabilitation, 2023. Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance: a systematic review and meta-analysis thirteen studies and 1016 participants comparing free weight with machine training for at least six weeks, with no difference between the two in muscle hypertrophy and strength gains specific to the kind of test used