HOW: Start in the quadruped position. Drive your hands into the ground and push the ground away from you. This is your starting “quadruped” position. From here, slowly lift one hand and tap your opposite shoulder while actively pushing your hand into the ground.
FEEL: You should feel your serratus anterior, the muscle under your armpit working.
COMPENSATION: The goal is to not let any part of your body move as your tap your opposite shoulder.