Chances are you've seen an exercise ball sitting in the corner of your gym (or maybe you even have one at home) and thought: What the heck am I supposed to do with this thing? After all, there are no handles to push or bars to grasp or levers to pull. It's not immediately apparent that you're looking at the best-kept secret in fitness.

Why are ball exercises superior to traditional crunches and back exercises performed on the floor? For one thing, the ball is unstable; you need to dig deep into those trunk muscles to keep the gizmo from rolling away. "You'll be astonished by how much balance the ball requires and how many additional muscles you'll use," says Mike Morris, a trainer in Seaside, Fla., and the president of Resist-A-Ball. Many of these exercises require the use of your arms and shoulders as well as your abs and lower back.

The ball also allows you to tailor a move to your fitness level. There's not a whole lot you can do to make a floor crunch tougher, but by rounding your back over an exercise ball (also called a Swiss ball), you can work through a greater range of motion.

Morris has designed a unique, intense trunk workout that will show you just how effective -- and fun -- an exercise ball can be. "The ball strengthens your torso, which is the foundation of your body," says Morris. "Your legs and arms are really an extension of your trunk. Exercising without strong core (ab and back) muscles is like trying to build a house by starting with the roof."

With stronger core muscles, you'll be able to put more oomph into your cardio workouts and lift heavier weights at the gym or at home. You'll never again be bored by crunches, and your posture is sure to improve. "Without losing a pound, you can look a lot slimmer because your strong trunk will keep you upright rather than slumped," Morris says.


For both abs and back, these exercises get progressively more advanced. If you're new to the ball, you might want to stick to the first exercise for each muscle group (abdominals and back extensors) until you feel comfortable enough to progress to the next 2. For each exercise, start with 1 set of 10-15 reps and progress to 2 and then 3 sets. When that gets easy, aim for 15-20 reps. Balance this program with upper- and lower-body weight training 2 or 3 days a week. Also do at least 30-45 minutes of cardio work 3-5 days a week.

Warm-up Start with 5-10 minutes of easy cardio exercise. Follow with some gentle movements like easy torso rotation, shoulder rolls and low leg swings, as you'll be relying on your arms and legs for stability.

Cool-down Finish with more stretching, focusing on your torso and lower back. Hold each stretch for 30 seconds without bouncing.