Pyramid Pose (Pārśvottānāsana) helps stabilize the SI joints and mobilize the thoracolumbar fascia BEFORE adding loading in Triangle (Trikoṇāsana), which can introduce some sheer at the SI joint. Pyramid Pose also teaches you the interoceptive skill of differentiating low back from hip movement, and gives you interoceptive information about the front leg's hamstrings and adductors - which is really useful for priming the sensory motor system before heading into Triangle. Also the feet and pelvis