The machine crunch sits you against a pad and loads the same spinal flexion as a floor crunch from a weight stack. It is the easiest loaded ab exercise to get right — the machine fixes your hips and your range, so the two things people get wrong on a cable crunch are decided for you.
How to do it
- Set the pivot at your waist, not your chest.
- Curl the spine rather than folding at the hip.
Common mistakes
- Loading it heavily and moving through a few centimetres.
What it trains
- Abs
- flex the trunk against the pad — the prime mover on a fixed path
- Obliques
- assist through the same flexion, without much rotation to do
- Hip flexors
- contribute on machines that pin the feet, less on those that do not
Variations and alternatives
Common questions
How do I set up an ab crunch machine?
Seat height so the pivot sits at your waist rather than your chest, and the pad against your upper chest or over your shoulders depending on the design. If the machine bends you at the hips instead of the middle of your torso, the seat is too low.
Is a machine crunch better than a cable crunch?
It is easier to do correctly and easier to take to failure. The cable gives you more freedom in how you curl and works the stabilisers a little more. If your gym has both, the machine is the reliable one and the cable is the one worth learning.
How many reps on a machine crunch?
Ten to fifteen, controlled, with a pause at the short end of each rep. If you are doing twenty-five it is set too light — this is a loadable exercise, so treat it like one.
In StackUp. Logged as weight and reps per set, and your heaviest working set decides whether the weight goes up next time. Get the app.
Core
