Popsugar Fitness Workouts What Does Having a Strong Core Mean? A Trainer Says This Is the Biggest Difference Between a Strong Core and a 6-Pack June 10, 2019 by Tamara Pridgett View On One Page Photo 5 of 13 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 5 Circling Plank Begin in an elbow plank with your forearms resting on the top of a ball. Keeping your core strong and your body still, use your arms to roll the ball in a small clockwise circle. This completes one rep. Previous Next Start Slideshow Fitness TipsWorkoutsCore ExercisesTrainer Tips