Push/Pull Isometric Core Strengthening

You can use a pole, a door jam, the lip of your sink, or any other solid, fixed object that allows you to pull with one hand and push with the other. This push/pull should be connected into your core. It can be done in sitting or standing. In standing, you can use a parallel and/or staggered stance. I recommend varying your positioning.
The general guidelines I use for this exercise are: 10 sec holds, pushing with one hand and pulling with the other; 50-75% of full effort; spine vertical; try not to hold breath as you tighten the core; modify effort or stop if have pain.
Goal: 10 sec push with left/pull with right, 5 sec rest, repeat but alternate push/pull hand. Do 10 reps of this for a set. Do 3 sets. If standing, do a set in parallel stance, a set in left foot forward staggered stance, and a set in right foot forward staggered stance.