Allow me to answer this way:
I enjoy exercise; I started lifting a few years ago and my max bench was around 190#, my max barbell back squat was 185# and my best deadlift was 315# for 4-6 reps.
Three years later, I’m easily maxing my bench at 255#, squatting 285# and deadlifting 415# for 6 reps (after back surgery a decade ago, I don’t do a one rep max deadlift).
Anyway, I’ve been busy in my small business and haven’t lifted in 6 months; thankfully, my job is very physical.
Regardless, I can still move about 90% of my max lifts with ease. I’d say that my strength gains were “permanent”. Now, consider the fact that I’m 43, you must know that I will not gain strength indefinitely, right?
However, I do feel that the strength gains I made are as “permanent” as they can be, considering the fact that muscles lose strength as we age.
PE growth is likely not too different!
That’s just my two cents, but I hope it’s thought provoking.
-Horseman-
BPEL 6-3/4" MEG 5-1/4" on 8-2021. Goal: 7-3/4" to 8"BPEL x 5-1/2" MEG
5'-11" and 190# and working back down to decent ab definition. I expect this around 178#.