McKenzie trained therapists have known for decades that most people have a directional preference of lumbar extension or a unilateral variant of such as sidegliding or flexion/rotation.
Why do most people respond to extension? It's simple and a concept I am using more and more in The Eclectic Approach, people need variability. If the average person slouches (but does not have pain) plus forward bends upward of 1000s of times a day, more unloading is not going to make someone better.
I wrote previously about flexion Rapid Responders here, and remember that two of those cases were my wife after giving birth and being in anterior pelvic tilt for months of the final trimester. She resumed prone press-ups ASAP and ended up needing flexion to reset her system.
|Swayback even seen in prone lying|
Look at this recent patient above, he has a moderate swayback, and even in prone, is still in more lordosis than most. Not that structure matters for pain, but there is something about variance and threat that adds up. Standing upright and doing lumbar extensions tends to aggravate his pain, but he is already loaded in every upright activity. He responded to posterior pelvic tilts and was able to inhibit his posterior chain using the exercise below combined with diaphragmatic breathing.
Sure posture does not matter when studied, but it's the introduction of variability that resets the nervous system, not always something as simple or mechanical as postural correction.
To break the posterior chain tone, and decrease threat to squatting, deadlifting, the simple exercise below, posterior pelvic tilt with quadruped rockback and diaphragmatic breathing is very helpful.
Keeping it Eclectic....