- EquipmentMachine
- PatternCore
- Reps10 to 20 reps
- Joint loadNone flagged
Adjust the seat so the pads sit on your upper chest or the handles beside your head. Sit back with your feet secured.
First cueCurl the ribs toward the pelvis.
How to do the Machine Crunch
Set up. Adjust the seat so the pads sit on your upper chest or the handles beside your head. Sit back with your feet secured.
- Curl your torso forward and down by contracting your stomach.
- Pause at the bottom.
- Return under control.
Form cues
- Curl the ribs toward the pelvis.
- Keep the hips still.
- Do not pull with the arms.
Common mistakes
- Pulling with the arms.
- Letting the stack crash between reps.
Muscles worked
Main target: Abs. The rectus abdominis runs down the front of the trunk. It curls the trunk forward and, more often in training, stops the spine arching under a load.
On the way: Obliques.
Its other side: Lower back, in the trunk pattern.
What to pair it with
Movements that round out a workout with the Machine Crunch, from the same catalog the StatBlockFit app logs.
- Reverse Hyperextension Superset partner: it trains the other side of the trunk pattern, so the two can alternate.
- Cable Woodchop Often left out: it trains the obliques, a job the moves above leave undone.
A complete workout around it
4 movements, the Machine Crunch first, at the catalog's rep ranges. Load it into the workout builder to change the sets, reps and weights, then bookmark it or download it.
- Machine Crunch 3 × 10 to 20 reps
- Reverse Hyperextension 3 × 10 to 20 reps
- Cable Woodchop 3 × 10 to 20 reps
- Captain’s Chair Knee Raise 3 × 8 to 20 reps
Alternatives and swaps
The same main muscle with other equipment: a swap never changes the muscle a workout trains.
Home or dumbbell swap
Hanging Leg Raise
Bodyweight
Gym or cable swap
Cable Crunch
Cable
A swap describes the movement, not your body: if a joint hurts, ask a professional before you train it.
Working weight and 1RM calculator
Enter a set you did: the weight, the reps and how many more reps you had left in you. The estimate is the formula the StatBlockFit app uses for its records, weight × (1 + (reps + reps in reserve) ÷ 30); above 12 reps it is rough.
Training zones
| Zone | Share of 1RM | Usual reps |
|---|---|---|
| Strength | 85 to 90 % | 3 to 6 |
| Muscle growth | 70 to 80 % | 6 to 12 |
| Endurance | 60 to 65 % | 15 to 20 |
A warm-up before the working sets: 50 % for 5, 70 % for 3 and 85 % for 1, each rounded down to a plate.
Common starting points, not a prescription: the right weight is the one you can lift with good form for the reps you planned.
Variations and preparation
A variation of: Cable Crunch.
Do before it: Dead Bug (bracing).
Track it in StatBlockFit
In the StatBlockFit app the Machine Crunch is logged set by set: the app suggests your next weight after each session, times your rests, keeps your records and shows the 72-hour recovery of every muscle on its training map. The training guide explains how.
Questions
How do you do the Machine Crunch?
Set up: Adjust the seat so the pads sit on your upper chest or the handles beside your head. Sit back with your feet secured. Steps: 1. Curl your torso forward and down by contracting your stomach. 2. Pause at the bottom. 3. Return under control. Form cues: Curl the ribs toward the pelvis. Keep the hips still. Do not pull with the arms. Common mistakes: Pulling with the arms. Letting the stack crash between reps.
What muscles does the Machine Crunch work?
It trains the abs as its main target and works the obliques on the way.
What can I do instead of the Machine Crunch?
At home: Hanging Leg Raise. In a gym: Cable Crunch. Each trains the same main muscle.
What should I pair the Machine Crunch with?
Good partners in the same workout are Reverse Hyperextension and Cable Woodchop.
How heavy should the Machine Crunch be?
Pick a weight you can lift for the planned reps with one or two left in reserve. As a common starting point, sets of 3 to 6 reps use about 85 to 90 percent of your one-rep max and sets of 6 to 12 reps about 70 to 80 percent; the calculator on this page does the arithmetic.