This one Pilates abs exercise is better than a hundred sit-ups if you want to build functional core strength—here's how to master it

Woman lies on her back on exercise mat smiling.

I had the pleasure of attending my first reformer Pilates class a couple of weeks ago and discovered a multitude of novel ways to strengthen my core. One in particular left its mark on me—the corkscrew exercise.

It involved lying on my back, lifting my hips off the deck and, keeping my legs extended, drawing a large circle with my feet. "It's a killer," says Pilates teacher Anna Mounsey-Jennings of Avalon Pilates. "It'll fire up your abs like nothing else."