How do you get the line down your abs like these models?....

I have pretty good abs. I just want to get a split line down the middle of my abs the best I can. You know...I guess it just shows them off better and gives them better definition. Really separated abdomens are nasty...I think those come from genetics.

I heard doing standing crunches makes that line down the middle of your stomach. It's kinda like a dance move but you contract hard when you do the standing crunch. Basically arching your back a little and contracting the abs.

Anyway here is what I'm talking about...

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