Plank with Reach Back and Out
To do the Plank with Reach Back and Out, set up in a Front Plank from your hands and toes with your hands under your shoulders and your feet about hip-width to shoulder-width apart. For this move, you will want your feet wider to create a more stable base. Beginners can do this move from their knees.
Then from the Plank position, reach one hand back and across toward the opposite ankle, pushing your butt back and up toward the ceiling as you reach. Then reach back forward and out toward the wall in front of you, dropping your hips back into a nice plank position.
Do not drop your hips too low and feel your low back engage. Keep your core tight to protect your low back as you come back into that nice plank position. Reach back and across with the same hand until all reps are complete on that side.