What's better for your obliques: weighted Russian twists or dumbbell chops?

Nothing makes a six pack pop like carving out those side lines. And if you want to tone em, you need to target the obliques in addition to the rest of your core work.

There are a number of oblique-sculpting moves to choose from. But what's really the best way to chisel the sides of your abs, stat? We asked Pete McCall, C.S.C.S., a San Diego-based trainer and host of the All About Fitness podcast, which is the ultimate oblique sculpting move: the weighted Russian twist or the dumbbell chop?

McCall says it's the the dumbbell chop, hands-down. For starters, a standing exercise will always trump one that requires you to be seated or lying down because our muscles are designed to be most effective when we’re standing on our feet, he explains. (Torch fat, get fit, and look and feel great with Women's Health's All in 18 DVD!)

What’s more, the seated Russian twist is prone to error more often than the chop. Here’s why: To do any rotational exercise, you want the movement to come from the hips or the thoracic spine, which has the vertebral structures to allow for rotation, McCall explains. When you sit to do a Russian twist, unless you've perfected the form, you could potentially put strain on the lumbar spine, right below, which doesn’t have the same kind of mobility.

A standing dumbbell chop, on the other hand, uses the hips, which will keep your back safe while carving your obliques. Bonus: “In addition to the obliques, your adductors, glutes, and hamstrings are all activated, as well, to create the movement,” says McCall.

So when in doubt, the chop is your way to go. But that doesn't mean you should nix the Russian twist altogether. You may just want to work with a trainer to really nail the form and make sure you're not putting your back in harm's way. (Worth noting: It doesn't hurt to do the move sans weights until you've really got the alignment down.) To try each move for yourself, here's a full rundown of what to do:

Weighted Russian Twist

How to: Sit on the floor with your knees bent and feet elevated. Hold a dumbbell vertically in front of your chest, and lean back so that your torso is at 45-degree angle to the floor. Turn your torso to the left, pause, and squeeze your abs muscles. Return to center. Repeat to the right side, and return to center. That's one rep.

A Dumbbell Chop

How to: Grab a dumbbell, and hold it with both hands above your right shoulder. Swing the dumbbell down and to the outside of your left knee while bending at your hips. Switch sides.