Rear delt fly machine vs Dumbbell Rear Delt Row
Swapping Rear delt fly machine (Machine) for Dumbbell Rear Delt Row (Dumbbell) retains 100% overlap; expect independent unilateral stabilization. Compare exact 17-muscle fractional recruitment before swapping equipment mid-session.
Side-by-Side 17-Muscle Recruitment Delta
How primary mover (1.0× set) and synergist (0.5× set) allocation changes when swapping Rear delt fly machine for Dumbbell Rear Delt Row.
| Muscle Group | Rear delt fly machine | Dumbbell Rear Delt Row | Leverage Shift |
|---|---|---|---|
| Shoulders (Deltoids) | Primary (45%) | Primary (45%) | Matched |
| Upper Back (Rhomboids / Mid-Traps) | Primary (40%) | Primary (40%) | Matched |
| Traps (Upper & Mid Trapezius) | Secondary (15%) | Secondary (15%) | Matched |
Load & Volume Conversion: Rear delt fly machine → Dumbbell Rear Delt Row
Worked weight heuristic: a 115 kg set on Rear delt fly machine (Machine) maps roughly to 38 kg per hand on Dumbbell Rear Delt Row (Dumbbell; 2 kg jumps, curve: extended end-range stretch with neutral wrist path). Calibrate set 1 at RPE 8 so e1RM history for Rear delt fly machine remains unskewed. Zero anatomical muscles are dropped between Rear delt fly machine and Dumbbell Rear Delt Row; 1:1 weekly set volume carries straight across.
Supporting Sports-Science Literature
| Study Title | Lead Author & Year | Verified Link |
|---|---|---|
| Front vs Back and Barbell vs Machine Overhead Press: An Electromyographic Analysis and Implications For Resistance Training. | Coratella (2022) | PubMed 35936912 ↗ |
| Upper limb muscle volumes in adult subjects. | Holzbaur (2007) | PubMed 17241636 ↗ |
| Muscle activation patterns while lifting stable and unstable loads on stable and unstable surfaces. | Kohler (2010) | PubMed 20072068 ↗ |
| Quantifying 'normal' shoulder muscle activity during abduction. | Wickham (2010) | PubMed 19625195 ↗ |