Bridge: spine is going into extension. So taking pelvis into a posterior tilt - bring lumbar somewhat in flexion just the opposite of biomechanically what we want in a back bend. Never understood this cue in bridge - they do in Pilates as well, makes no sense
You actually won't be able to keep the spine in flexion in bridge (or cobra); the cue is to create a counter balance to the extension since most people over-extend at L-5/S-1, and/or other lumbar vertebrae junctions often causing lower back pain, or exacerbating already existing pain. By resisting the extension space is created along the front of the spine so the back bend isn't too deep. In my classes I encourage people who feel easy with a deeper extension to let go of that resistance. Hope this helps.
Hi there Patricia, So nice to hear this from you! I lost my password so had to deal with that before responding to you, silly me. Thank you for practicing with me and for taking the time to comment. Much Love, P