You could try Jacobson relaxation technique. My experience is that it works like an early warning system. You very fast learn to notice the tension the moment it starts, instead off when it starts to become painful.Every time I get stressed, my upper abdominal muscles tenses up and it is painful and wreaking havoc on my digestion. I'm working on reducing the stress and also on healthy coping mechanisms (meditation etc.), but I have mixed results so far. Is there anything that might help the muscles to relax / loosen up?
Look into Trauma Release Exercises (TRE), that'll dig through the tension, particularly in the psoas which is a key driver in the stress -> tense gut -> ineffective digestion -> stress loop as it carries a lot of nerve activity from the hips to the spine. It's truly a remarkable feeling using these methods.
I think the holding pattern is tied to the freeze response in polyvagal theory, which TRE can help to release. Otherwise, mysofascial massage on the gut, and general stretching/use of a foam roller or a device like Pso-rite.
A physical intervention is ultimately going to shift things the most, nutrition and avoidance of irritants is helpful but if you've got unhelpful compensating muscular patterns, those patterns have to be reset, not just supported internally. That said, high dose epsom salt baths a few times a week can be really effective for some people.
Short video touching on trauma, tension and polyvagal theory from Stephen Porges
Good brief introduction to TRE by the creator, David Berceli
Video tutorial for TRE I use sometimes
It appears this one has been taken down, however there are a number of walk through videos on youtube. I used to use a sheet of paper with the sequence that I transcribed from one of the TRE ebooks and memorised. As a side note: I think it's helpful to think of TRE in several phases as it really is quite a unique body phenomena compared with other 'exercises'.Anyone have this 3rd video?