"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 ...

While many workout regimens flame out as quickly as it took them to start trending, others stand the test of time. Exercises like tai chi, running, swimming, hiking and yoga, for instance, have been ...

Our core is made up of four muscle groups that are essential to everyday movements, like walking and lifting. And when people think about core strengthening, crunches are often the first thing that ...