Flat Abs Fast: Core-Sculpting Resistance Workout

How It Works

If you envy A-list abs like Kate Beckinsale's, we've got one word for you: rubber. "Using a resistance tube boosts the firming power of any ab move," says instructor Linda LaRue, who created the Core Transformer class at Equinox Fitness Clubs in Los Angeles and has a list of devoted Hollywood fans including Beckinsale. LaRue put together her best new belly flatteners using this secret-weapon shaper exclusively for FITNESS. Do two sets of each move, working your way up to three sets, on three nonconsecutive days a week. Mix the order every time to really whittle your middle.

What You'll Need: A resistance tube with handles, a sturdy chair

Quick Tube-torial
Resistance tubes come in various color-coded levels, from low resistance (the equivalent of a 3- to 5-pound dumbbell) to high resistance (20 or more pounds). A typical tube is about 4 feet long, like Perform Better's Economy Tubing with Handles ($7.95; performbetter.com). If any move gets too tough using a tube, continue without it -- LaRue says, "Your abs will still get a great workout." Once you've aced this routine, try a tube with heavier resistance for even more definition.

Do the Twist! When crossing the resistance tube into an X shape for each move, twist it around twice before grasping the handles, so the point of intersection is solid. "Twisting the tube increases the pull and resistance on your core," LaRue says, giving your abs maximum toning from every angle. You can aim to start with the X at belly-button level, but "it doesn't matter if the intersection moves around a bit," she adds.