Loaded crunches for serious ab thickness.
Crunch with your abs, not by pulling with your arms or hip flexors.
The ab crunch machine puts a number on your ab training, loading spinal flexion, ribs curling toward hips, with a stack you can progress like any other lift. The seated setup locks your legs and arms in place so the abs alone drive the crunch, and the resistance stays on them through the return. If you want abs that are thick enough to show, this is where they get trained like a real muscle instead of burned out with endless floor reps.
Moderate weight for controlled reps in the 10 to 20 range beats stacking it. If you have to yank the handles with your arms to move the weight, it's too heavy for your abs.
You're probably hinging at the hips or pulling with your arms. Set the seat so the pivot lines up near your bottom ribs, then think about curling your ribcage down toward your hips, short and hard.
It's progressable, which floor crunches stop being once you can do dozens. Load that you can add to over months is what makes abs grow, so the machine wins for building, the floor is fine for finishing.
