Obliques with Small Ball is a variation of the original Pilates exercise âÂÂObliquesâ (or âÂÂCriss-Crossâ as it is sometimes called). Adding the small ball under the back increases the instability of the exercise, thus increasing the challenge to the core. YouâÂÂll tone and strengthen the abdominal muscles, especially the internal and external obliques, and target the deep muscles that stabilize the spine. Spinal flexibility also increases as you engage the abdominal muscles through flexion and extension. Please visit www.PilatesOnFifth.com (for more info), www.UltimatePilatesWorkouts.com (for more videos) and www.Shop.PilatesOnFifth.com (for store).