Unfortunately, when this occurs, the muscle does not participate in normal joint movement, and other muscles in the area compensate to take up the slack. This is never perfect because it's a short-term fix. Ideally, that injured muscle heals quickly and gets back into action. The brain restores nerve signals to the muscle and it is again able to support it's correlating joint(s) through full range of motion. In short - you feel better and get back to "roller-disco-dancing" without a hitch. ;-)
Sometimes, however, the body is never able to reactivate the hypo-tonic muscle.
Commonly, it's a case of nutritional shortage. Because the body apportions a majority of its nutrients to the immune system, the liver, and the brain, it can't spare all that is needed to heal the much less important singularly injured muscle, so it heals it "just enough" to get by and leaves it at that.
A small percentage of the time, the brain leaves the injured, hypo-tonic muscle turned off for reasons we do not understand. That's not often, but, with all the injuries you can accumulate in a lifetime, they can add up. Soon, your body's collection of non supportive, hypo-tonic muscles lead to skeletal misalignment, and your posture gets a little cranky and creaky. Then - more injuries followed by more pain ensue, and the cycle is repeated.
So, if you've been "ignoring" an injury or a chronic ache, sit up and pay attention. It's your body's way of saying it needs some good ole TLC...
“Listen to your Body”
John Aaron Villarreal