I.A.N.A.D., but I can speak from firsthand experience with a certain level of accuracy. On September 21, 2000 I broke my back in a fall. I was placed into a Boston Overlap Brace. As you can see, it is a form-fitted device moulded to a dozen or more measurements from my torso, with strapping along the front.
This is regarded as “walking traction” by Orthopedists. That is to say, I was not bedridden, but obliged to wear this unless laying down or showering. It prevents 100% of bending or twisting motions while in use.
By September 30th I had the brace on. By Thanksgiving I was aware of serious atrophy. Previous to the injury, I was fat- but posessed of a highly developed set of muscles, ligaments and tendons along the middle and lower back due to the kind of camera harness I wore for my career. The Dr’s opined that the extend of musculature prevented my injury from being worse.
By Thanksgiving- 2 months in the brace- I had lost most of that strength. By New Year, my back was badly supported in the lower areas. ( Underneath the belly had been fairly nice abs. Not to look at, but to USE. They did a lot of the work with the camera harness. They too went away ).
So, I can answer the O.P. by saying that in my particular case, within 2-3 months I suffered very profound atrophy of abdominals, lower back and supporting muscles. They have not returned to anything like what they were pre-injury. As an aside, I had no surgery involving cutting so I can say that the lack of musculature and ligament/tendon strength is in no way due to any treatment post-injury.
Use it or lose it…