Psst: it's not another plank.

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 ...

If you suffer from a bad back, you know just how frustrating it can be to do everyday tasks, including workouts and especially ab exercises. That's because your core and your back are closely linked.

When you talk about strengthening your core, you’re probably thinking about your abs. In particular, you may be focusing on your rectus abdominus (that’s the six-pack muscle). The rectus abdominus ...