Stop doing crunches: I tried flutter kicks for a week, and the results surprised me!

Here's what happened when this writer did flutter kicks for a week ...
Business Insider

Want strong abs? Personal trainers say to skip crunches and do these 6 exercises instead.

Crunches and sit-ups aren't the only way to build strong abs. Underrated exercises like planks and flutter kicks are effective, low-impact alternatives. Doing different core exercises also helps add ...