Add Yahoo as a preferred source to see more of our stories on Google. There’s no greater hallmark of fitness than a six-pack, which is why there’s typically no shortage of crunches and leg raises in ...

Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. This is a great ...

Psst: it's not another plank.