reckonerDumbbell fly
The chest movement with no elbow work in it. Nothing here ends because the triceps gave out, which is the whole reason it exists beside a press rather than instead of one.
Soft elbows, feel the chest stretch.
- Pattern
- Horizontal push
- Trains
- Chest, front delts
- Kit
- Dumbbell, bench
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 8 to 12 reps at RPE 8
- Progression step
- 1 kg once the top of the range is clean
- Skill
- Some technique
- Recovery cost
- Low
- Not prescribed if you have declared
- Shoulder
Muscles worked
How to do it
Get set the way you would to press
Sit on the end of the bench with a bell on each thigh, lie back and kick them up over your chest one at a time. Shoulder blades together and down into the bench, feet flat on the floor.
Fix the elbows and leave them
Press the bells up, then put a small bend in each elbow and hold exactly that bend for the whole set. Every degree the elbow gives back on the way up is a rep the triceps helped with.
Open to chest level
Let your arms travel out in a wide arc until your upper arms are roughly level with your torso. That is the bottom of the movement. The floor is not the target and neither is the bench.
Close your arms rather than lift the weight
Bring the bells back along the same arc and stop them just short of touching. Thinking about closing your arms and thinking about pressing a weight up produce two different movements, and only one of them is this one.
What goes wrong
Going heavy enough that it becomes a press
The elbows start bending on the way up and it quietly turns into a poor dumbbell bench press. This is one of the few lifts where a heavier bell buys you less.
Dropping the elbows below the shoulder line
Past that point the arms have run out of the arc the chest closes, and the front of the shoulder is holding a loaded arm at the end of its own range. Upper arms level with the torso is the bottom.
Asking it to do a press's job
In a direct comparison the barbell bench press produced higher chest activation than the dumbbell fly through most of the lift1. Put it after a press in the session, not in place of one.
How Reckoner progresses this lift
Six weeks of this lift, from 10 kg, 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 8 at 10 kg | More reps 8 → 9 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 2 | 3 x 9 at 10 kg | More reps 9 → 10 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 3 | 3 x 10 at 10 kg | More reps 10 → 11 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 4 | 3 x 11 at 10 kg | More reps 11 → 12 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 5 | 3 x 12 at 10 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 10 kg | Load up 10 kg → 12 kgYou hit the top of the range at RPE 7, so the bar goes up 2 kg to 12 kg and reps reset to eight. 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
How heavy should a fly be?
Much lighter than anything you press, and it climbs in smaller steps. The library gives this movement a smaller increment than either bench press, which is a fact about the movement rather than a rule of thumb, and you can read it in the fact block at the top of the page.
Why does it stop at chest level and not lower?
Because the bells can travel further than a bar could, which is the point of the movement and also the thing that has to be given a stopping point. Below the line of the torso the chest has run out of range and the shoulder is carrying it.
What does Reckoner do if this lift stalls?
It eases the load and lets you rebuild toward the weight before it does anything else, and only offers a different movement if the same wall comes back. Rotating is the last answer here, not the first, because a swap costs you that movement's whole loading history.
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
- Solstad and colleagues, Journal of Sports Science and Medicine, 2020. A Comparison of Muscle Activation between Barbell Bench Press and Dumbbell Flyes in Resistance-Trained Males higher pectoralis major activation in the barbell bench press than in the dumbbell fly across the whole movement and the majority of its phases