This video demonstrates Plank, which strengthens your entire core, front and back, while also taxing your shoulders and arms. Start with a few seconds hold time, either on your forearms or in full plank with arms extended; hands below your shoulders. I demo both positions, as well as the most challenging – going back and forth from forearms to full extension and back. You’ll notice a good cardio kick too, doing the back and forth one, half a dozen times or so, and repeating. Enjoy this easy to learn move that has a big payoff.