This may explain two problems, one is that your spine does not fluctuate in sequence, and the other is that you may not master the strength skills, resulting in excessive strength of hip flexors. These two reasons can also appear at the same time

As shown in the figure, because the gluteal flexor muscles are concentrated near the first lumbar segment, the tension here is very concentrated, and the upper body gravity falls down in order, so this point will form a strong shear force, while the normal abdominal muscles will pull the sternum, then the ribs, and then the chest ribs. Many ribs are equivalent to dispersing the chest, and the sternum is a whole piece of ribs. Judging from the deconstruction and stress distribution, it will not be injured.