Hollow Body Hold

Try the hollow body hold. Daily ab training at the adequate level of intensity is one of the most rapid ways of improving abdominal aesthetics, provided you're lean enough to show them.

The "abs are made in the kitchen" mantra is not quite accurate for most people. Abs are simply revealed in the kitchen. This just means that to have visible abs you must be lean. And building them through direct training will increase the likelihood of seeing them. It'll also make it easier to see them at a slightly higher body fat level.

Take me for example, even when I’m at a higher body fat percentage (around 13-15% body fat) I can still see a clear 6-pack because the muscle bellies of the rectus abdominis are so thick that they create a contrast between themselves (the "packs" portion) and between the tendinous sections that separate them.

Pair this exercise with one that requires added resistance, and so that you fatigue at 6-12 reps. When training abs daily, superset one loaded abdominal movement with an unloaded one like this. Then do 3 sets of one superset on each day. – Christian Thibaudeau