Exercise of the Week - Ball Crunch

Ah, the good old crunch. No matter how many ab exercises we come up with, basic crunches remain a staple for many of us because nothing targets the rectus abdominis (the fancy name for the outer ab muscles that make up the elusive 'six-pack') better than flexing the spine, which is what we do during crunches.
Today, I want to highlight crunches on the ball because they're simple, effective and more dynamic than crunches on the floor. Just lying down on the ball will activate your abs as well as your legs and glutes. Lying down for floor crunches doesn't activate much except maybe the desire to take a nap.
What I like about using a ball is that, first, you can change your positioning to make the exercise easier (e.g., staying at more of an incline) or harder (e.g., lying in a tabletop position). I also like that you can stretch back over the ball to increase range of motion.
Do it right: Sit on the ball and roll down until the ball is under your lower back (easier) or mid-back (harder). Place hands behind the head to gently support the head and squeeze the abs to lift the shoulders off the ball. Imagine that you're pulling the ribcage toward your hips. As you crunch up, try not to roll on the ball, but keep it stable. Lower down and repeat for 1-3 sets of 10-16 reps.