Day twenty one and today’s tabata is planks. Do your favorite plank or do different plank variations for each set. So for example, you could do side planks, planks with one arm up, or one leg, or one leg and one arm up, and the front of elbow plank or top of push up plank. Do 20 seconds of plank, followed by 10 seconds rest for 8 sets for total of 4 minutes. Be sure to keep spine straight and belly pulled in and engage the back side as well as the front.