The phrase "standard plank" refers to a common exercise called the plank. It involves holding your body in a straight and rigid position on your forearms and toes, like a plank of wood. Full definition
They have either a smooth or lightly textured finish, with most designs supplied in standard plank size. (karndean.com)
So, don't let your ab routine become boring or ineffective by doing only standard planks. (cathe.com)
Depending on how fit you are, you can try doing standard planks, reverse planks, side planks, rowing planks or if you feel confident you can try the plank crunches or the plank rollout. (fitnessandpower.com)