Now that we’ve finished the planks (for now), let’s work on our obliques and lower back.
With a five to fifteen pound weight (or a medicine ball) on the floor next to you, sit down with your legs extended, roll your shoulders back and sit up as tall as you can. Keeping your back straight, lean back until you feel your abs engage. For a greater challenge, lift your feet ever-so-slightly off the floor. Twist to the right and pick up your weight or medicine ball. Holding the weight, twist from right to left, reaching as far behind you as possible while maintaining your form. (http://running.competitor.com/2012/02/news/four-key-core-exercises-for-runners_41874/4)
I plan on working my way up so that I can do a total of 40 full twists. Since I don’t have a medicine ball at home, I will do mine without weights, unless I’m at the gym.
This move targets your entire back, an essential part of your core. Lie on your stomach with your arms and legs extended so you look like Superman flying through the air. Lift your right arm with the left leg, then alternate sides. Practice variations of this move by only lifting the arms or only lifting the leg, or both arms and both legs at the same time. Focus on extending your limbs long and out rather than simply lifting up. (http://running.competitor.com/2012/02/news/four-key-core-exercises-for-runners_41874/5)
I plan on doing a total of 20 alternating among the variations.