Ab exercises with dumbbells

Why add weight to crunches at all?

Abs are a muscle like any other and they respond to resistance. Without it a set usually ends when your patience runs out, not your strength. With a dumbbell it fits inside a rep count you can remember and compare with last week.

That does not mean there is no progress without one. With no equipment you adjust the difficulty with the lever of your own legs and arms, and that road is a long one. A dumbbell is simply a simpler version of the same principle: instead of hunting for a harder variation, you move the same weight further from your hips or pick up a heavier one.

The limit is often the grip and the shoulders. In sit-ups with a dumbbell overhead it is rarely the abs that quit first, because the arms holding the weight in one spot tire sooner. Versions with the dumbbell held on the chest usually let you use noticeably more load.

Why one dumbbell in one hand?

Because it is the simplest way to load the abs unevenly. A carry with a dumbbell at one side, the side bend, the windmill and the side plank with a dumbbell all put the torso in a situation where the weight drags it one way and the muscles on the other side have to refuse. In a gym a cable does this; at home a pair of dumbbells is the closest equivalent.

That work looks unremarkable, because almost nothing moves. A one-arm carry does not even have reps: you walk straight ahead at an even pace and keep the dumbbell from swinging and the torso from leaning. The effort only becomes obvious once the weight gets serious, and at that point it is usually the grip that gives out first.

The side bend and the diagonal chop belong to the same family, only with movement. The first runs the obliques through a full range in the side plane; the second combines rotation with a lean and asks you to turn your feet along with the torso, so the hips and knees don't get left behind.