Machine Crunch — Muscles Worked & RPE Load Guide
FR: Machine Crunch · High output close to 0 RIR with minimal CNS tax
Machine Crunch targets Abdominals & Trunk Bracing as primary movers (1.0× set credit). Cam-matched resistance across sticking points.
Primary Movers (1.0×)
Abdominals & Trunk Bracing
Full 1.0 hard-set credit per set
Secondary Synergists (0.5×)
Minimal synergists
Fractional 0.5 set stimulus
Equipment & Pattern
Machine
External / Standard Load
CSV Import Aliases
1
Strong, Hevy, Capua & Jefit
17-Muscle Fractional Recruitment & Weekly MEV–MRV Landmarks
Each working set ≥ RPE 6 triggers fractional hard-set credit toward Renaissance Periodization / Schoenfeld weekly hypertrophy landmarks.
| Muscle Group | Mechanical Role | Effort Share | Weekly Optimal Band (MEV–MAV) | Frequency & Research |
|---|---|---|---|---|
| Abdominals & Trunk Bracing | Primary (1.0× set) | 100% | 6–20 sets/wk (MRV 25) | 3–6x / week · Evidence |
Machine Crunch Worked Wathan RPE Prescription Table (kg)
Worked kg values computed for Machine Crunch using a worked 55.0 kg reference 1RM (Machine) rounded to 5 kg machine increments. Mechanics: Externally braced cam track; resistance curve: Cam-matched resistance across sticking points.
| Reps | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7 |
|---|---|---|---|---|---|
| 3 reps | 0 kg (82%) | 0 kg (82%) | 0 kg (82%) | 0 kg (82%) | 0 kg (82%) |
| 5 reps | 0 kg (82%) | 0 kg (82%) | 0 kg (82%) | 0 kg (73%) | 0 kg (73%) |
| 8 reps | 0 kg (73%) | 0 kg (73%) | 0 kg (73%) | 0 kg (73%) | 0 kg (64%) |
| 10 reps | 0 kg (73%) | 0 kg (64%) | 0 kg (64%) | 0 kg (64%) | 0 kg (64%) |
| 12 reps | 0 kg (64%) | 0 kg (64%) | 0 kg (64%) | 0 kg (64%) | 0 kg (64%) |
Strong, Hevy & French/English CSV Import Labels
STRUGGL automatically maps these exact workout-tracker strings to canonical Machine Crunch volume and e1RM records on zero-login Wrapped CSV upload.
Machine Crunch
Taken-Rack Substitutes & Biomechanical Swaps
Ranked deterministically by weighted primary-muscle overlap inside the same measurement family.
Verified Peer-Reviewed Literature (PubMed & DOI)
| Peer-Reviewed Paper | Author & Journal | External Reference |
|---|---|---|
| An electromyographic analysis of the Ab-Slide exercise, abdominal crunch, supine double leg thrust, and side bridge in healthy young adults: implications for rehabilitation professionals. | Youdas (2008) · Journal of strength and conditioning research | PubMed 18978615 ↗ |
| Integration core exercises elicit greater muscle activation than isolation exercises. | Gottschall (2013) · Journal of strength and conditioning research | PubMed 22580983 ↗ |
| EMG activation of abdominal muscles in the crunch exercise performed with different external loads. | Moraes (2009) · Physical therapy in sport : official journal of the Association of Chartered Physiotherapists in Sports Medicine | PubMed 19376473 ↗ |