Adds load to the classic crunch for thicker abs.
Curl your ribs toward your hips, don't yank your neck forward.
Adding a weight on the chest turns the crunch into a proper progressive exercise, so the abs get trained like any other muscle, with load you can increase over time instead of endless reps. The short curling range stays the same, ribs drawing toward hips, but every centimetre now costs more. It earns its place for anyone whose bodyweight crunches stopped being challenging, and it is the direct route to thicker, more visible abs.
Start with something you can control for 10 to 15 strict reps, a small plate or similar held on your chest. If the weight makes you jerk off the floor or pull your neck, it is too heavy.
On your chest, hugged tight, is the standard. Holding it behind your head increases the leverage and difficulty sharply, so treat that as a progression, not a starting point.
Once bodyweight reps get past 20 or so, adding load builds more strength and muscle than adding reps. The abs grow from progressive tension like everything else, so weight is the cleaner progression.
