How does this work. So you breathe in and contract your abs. First time you do it you may get some soreness due to the novelty aspect, but as Mike wrote, soreness does not necessariy mean anything positive. Then what? There is not really anything progressive abut it except perhaps add volume.
It sounds like “flex your bicep as hard as you can for 30 seconds”. You will shake with effort, you might get a bit of pump going, but that is it.
If this works, well, why not apply it to all other bodyparts. Flex and hold.