Dumbbell Shoulder Press vs Machine Shoulder Press
Swapping Dumbbell Shoulder Press (Dumbbell) for Machine Shoulder Press (Machine) retains 100% overlap; expect externally braced cam track. 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 Dumbbell Shoulder Press for Machine Shoulder Press.
| Muscle Group | Dumbbell Shoulder Press | Machine Shoulder Press | Leverage Shift |
|---|---|---|---|
| Shoulders (Deltoids) | Primary (50%) | Primary (50%) | Matched |
| Triceps Brachii | Secondary (28%) | Secondary (28%) | Matched |
| Traps (Upper & Mid Trapezius) | Secondary (12%) | Secondary (12%) | Matched |
| Abdominals & Trunk Bracing | Secondary (10%) | Secondary (10%) | Matched |
Load & Volume Conversion: Dumbbell Shoulder Press → Machine Shoulder Press
Worked weight heuristic: a 38 kg per hand set on Dumbbell Shoulder Press (Dumbbell) maps roughly to 55 kg on Machine Shoulder Press (Machine; 5 kg jumps, curve: cam-matched resistance across sticking points). Calibrate set 1 at RPE 8 so e1RM history for Dumbbell Shoulder Press remains unskewed. Zero anatomical muscles are dropped between Dumbbell Shoulder Press and Machine Shoulder Press; 1:1 weekly set volume carries straight across.
Supporting Sports-Science Literature
| Study Title | Lead Author & Year | Verified Link |
|---|---|---|
| Effects of body position and loading modality on muscle activity and strength in shoulder presses. | Saeterbakken (2013) | PubMed 23096062 ↗ |
| Muscle activation patterns while lifting stable and unstable loads on stable and unstable surfaces. | Kohler (2010) | PubMed 20072068 ↗ |
| Front vs Back and Barbell vs Machine Overhead Press: An Electromyographic Analysis and Implications For Resistance Training. | Coratella (2022) | PubMed 35936912 ↗ |
| Influence of exercise order on the number of repetitions performed and perceived exertion during resistance exercises. | Simão (2005) | PubMed 15705026 ↗ |