A plank is a simple exercise that delivers a hardcore workout for the body core itself. Simple because all you have to do is hold the initial push up position and keep a straight line. Don’t move as long as you can. The core muscles will start contracting which means you are doing it the right way. A normal plank exercise should take about 3 sets with aproximately 30 seconds per set. An easy variant of a plank is using the elbows to form “the table” instead of the arms. I’ll let the pictures speak for themselves.