Tight hip flexors / glutes
Shortened ligaments in the lower spine (from misaligned pelvis)
A combination of lots of biking, not much stretching and a job that involves a lot of sitting
Basically what I’ve had for the last few months – leading to a stretched back and tight neck / muscle spasms
Stretching only stretches the ‘good’ muscle tissue, not the knotted stuff. Physio will help loosen it, then use a golf ball / lacrosse ball to get the trigger points, and a foam roller to help lengthen stuff
google Evan Osar and look at some of his core breathing stuff / hip centration.
All this was the advice I got from my physio, so from personal experience