When you think about it, gravity can sometimes actually improve your ability to do an exercise. If you bend forward to touch your toes, for example gravity helps—at least a little. By comparison, if you sit on the floor and reach to touch your toes, you probably can't reach as far. And if you hang from a pullup bar and raise your feet to “touch” your toes to your hands…you get the idea.

That's why the windshield wiper, which combines an oblique twist with a hanging toe-touch, is so viciously difficult—and so effective for strengthening your entire body. We'll put it this way: It makes the toes-to-bar look cute. 

How to do a windshield wiper

  1. Hang from a bar overhead, pulling down with your lats—think about "shortening your armpits—so you’re engaging your shoulders and not just hanging out of your arm sockets.
  2. Squeeze your abs to bring your toes up toward the bar in a pike position.
  3. Slowly, with control from your obliques, move your legs side-to-side, holding them together like they’re one windshield wiper. Only lower to one side as far as you can control without twisting your hips—or losing your hold entirely. 

What's so great about the windshield wiper?

This supremely difficult total-body core move requires serious strength and control—especially in the oblique muscles, which tend to get under-developed with traditional ab training exercises.

Your core muscles need to contract to bring your legs up to the bar, contract isometrically to hold yourself up there, rotate when you twist your legs to each side, and resist that rotation (to stop your legs from falling to one side at the end of each twist). Plus, your back, shoulders, and forearms will be cooked just trying to hold you in place while you move your legs.

How can you use the windshield wiper?

End your strength workout with a few sets of these. Do as many as you can do with good form, aiming to keep the side-to-side even. And if you're a real glutton for punishment and/or a serious abdominal workout, combine it with the dip bar pike-up (do the wipers from the dip bar instead).

And if it's just a little too difficult, you can do a lying windshield wiper, which retains the side-to-side oblique motion and the isometric hold in your core, but without the grip strength test of a hanging windshield wiper: