Last week, I blogged about the idea of incorporating core work into traditional strength training exercises, namely with pushups and pikes on the ball. Because I'm on a core kick lately, I wanted to highlight another favorite combination, which also includes pushups. I find pushups to be excellent (my clients would insert the word "excruciating" here) work for the core and you can add even more excruciating excellence by adding in a side plank.
This exercise works everything, with a particular focus on the obliques as you rotate to the side and send the arm up in the air. You can modify by doing the pushup on your knees and then keeping one knee down in your side plank. You can also add intensity by holding a light weight in each hand as you lift the arm up.
Do it right: Get into pushup position on the toes or knees. Do one pushup and as you come up, shift your weight on the left side of the body and rotate to the side while bringing the right arm up towards the ceiling in a side plank. You can keep your feet staggered or you can stack them (which is harder). Lower the arm back to the floor for another pushup and then rotate to the other side. Repeat the series, alternating each side, for 1-3 sets of 10 or more reps.