The foundation of fitness for a mom is her abdominal area. To moms a flat stomach is wonderful; a strong abdominal core is critical. The cool thing is, you can get both at the same time with side planks.Side planks are great for toning, without enlarging, the obliques on the side of your abdomen. Strong oblique muscles also add powerful stability to your back. Asthetically, side planks can sculpt your stomach in ways crunches or sit-ups just can't do. The nice thing about side planks is they can.