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 ...

Plus, which move is more effective for strong abs.

Add Yahoo as a preferred source to see more of our stories on Google. Ever look at someone and think, “Man, how many crunches does it take to look like that?” If you want to tone your abs, ...