As mentioned in previous posts, I like the stability ball for many exercises. I am partial to the brand “FitBall” for its durability and feel. I’m holding it in gray, yet it comes in white and other colors. It also comes in two sizes; I prefer the 22″/50cm size as shown directly below.
Below I am demonstrating the don’t for your chin/neck position when laying back on the ball. It does feel good to just let your neck relax back momentarily for a passive backbend and neck stretch; no problem. However, when executing your ab crunches, do not let your head go ‘dead weight’ and fall backwards, only to snap it back in the up position.
Instead, as shown here below, is the “DO“; the correct neutral chin/neck posture. Imagine your holding an apple under your chin to your chest. For optimum control, with focus on your core, keep your neck and chin in this neutral position throughout the entire range of motion, and your elbows to the side.