HiBC listed one of the anatomical issues related to this sort of thing.
I remember a PT and a massage therapist working on a tight piriformis, but also a tightened psoas. Both were very understanding of the accumulated stresses caused by wearing thick leather gun belts on-duty, and then continuing to wear leather holsters against my hip on my off-duty time.
Both designs of thick leather belts were seemingly connected to the imbalance created in my hips for hours at a time, taking their toll over the years (meaning late 20's, 30's and into my early 40's).
Eventually sensitivity developed at the iliac crests, and then along the IT band (lliotibial band).
Due to a work-related shoulder injury, and then a mysterious brachial plexus problem, shoulder holsters are something I like to avoid (as is wearing a backpack).
The psoas muscles dislike wearing a too thick, wide or heavy belt along the abdomen and over the hips, so AIWB carry, for me, is a sure way to experience pain when sitting, and even when standing, over a long enough time.
Careful exercise and stretching (foam rollers, wedge, etc) are needed to address these conditions from becoming aggravated, which is a good way to remind myself to keep my hips (glutes/pelvis) and legs mobile. Occasionally I've also been using an ankle attachment for different exercise band/cables, with wall attachments, to work on the type flexible strength I used to enjoy as a younger martial artist.
More than 40 years and 40 pounds later, flexibility is different than when I was jumping and floating when working the heavy bag, although I enjoy the increased upper body weight and strength (which I wished I could've developed as a youngster
).
If I were able, I'd go back and start changing the size and weight of the handguns I wore on my own time, and the types of holsters I used to carry them. I'd also have switched to using a Buscadero rig for as many years as possible, to shift and spread out the pressure for my uniform gun belt, and have sooner gone to using the smaller and lighter compact pistols for my plainclothes assignment., Hindsight, right?
Looking at the young cops using the new "tactical suspenders" and soft synthetic "equipment belts" (what we used to call gun belts), perhaps they'll suffer less eventual imbalances and avoid some of the pain.