If you’ve ever worked with a trainer, attended a group class at the gym, or read a set of exercise instructions, you have, without a doubt, been told to “engage your core.” The fitness world is ...

Stronger abs without a single crunch? Yes, please. Here's how to do a plank the right—and why they're so good for you. Fact checked by Emily Peterson Meet the sit-up's even more effective sibling: the ...

"Hearst Magazines and Yahoo may earn commission or revenue on some items through the links below." If you've completed a core workout—or 100 of them—over the years, you likely know what crunches are ...