Herbalife fitness expert, Samantha Clayton shares her advice on how to do the perfect ab crunch. Avoid common ab crunch & sit up mistakes with this clear & simple ab crunch advice from Herbalife: don’t strain your neck & remember focus on your core. A few perfect ab crunches can be more effective than more ab crunches with poor form, so learn to perfect your ab crunching technique in this video & take time to work your core ab muscles properly.