Let's says a beginner builds a big chest from horizontal movements and then switches to vertical movements only. Would the chest atrophy or maintain it's strength and size?
Or vice versa, if someone does only vertical presses then switches to only horizontal presses, would the traps maintain or atrophy?
From my own experience the answer would be yes, because I used to do a lot of abdominal work and after stopping my abdomen has maintained its thickness and definition. And it has been 8 months since the last time I did anything—especially for the abdomen.
But is this only limited to abdominal muscles?