“pulling belly into the spine” is a really good description of the movement we are seeking. I shall explain it in more details to find the finer nuances needed to execute this feeling and gain from its benefits.
This lift includes lifting mula bandha, the pelvic floor muscles including the anus, the deep inner core muscles next to the pubic bone. This is a deep awareness which can build in time. For now we can keep looking into lifting the hips bones and lifting the belly in and up.
I think the biggest problem could be is when we are not in a relaxed state and we follow this instruction. It becomes more effort and increases the compensation, increasing the wrong alignment. Firstly then I’ll say to you, relax the lower back, even to the point of where your mother would disagree. As you now pull the belly into the spine there should be a broadening of the lower back and then you can feel to relax the ribcage. Imagine now pulling the belly in and up under the rib cage which will broaden the mid back. If you feel that the shoulders have dropped forward, don’t panic, continue lengthening upwards, sometimes all one needs here is awareness of lifting the chin and allow that to bring your shoulders and neck into a relaxed alignment.
Practice Mula bandha daily, increasing the flexibility in the lower back and releasing the tension from the belly.
Lifting the belly supports the entire back, which often takes a lot of strain and overuse.
It lengthens the lower back, due to the overuse is generally very tight and then trying to do back bends with a tight back doesn’t feel great at all.
It strengthens the core, which is the front belly and sacrum area, the whole pelvic girdle.
It aids in engaging the legs, opens the shoulders into correct alignment and lessens compensation due to habitually tightened muscles. It increases the strength and flexibility in any pose.
Good luck and enjoy. Any questions, please forward them to me, I’ll try my best
Much Love, Namasté