I work in a fairly physical job and as my E levels have climbed and my T levels have dropped, have noted loss of upper body strength. Cannot say there is pain associated with it, but things that used to be easy now require real effort. I started Yoga about the same time I started working on my hormonal balances. If anything, I would say that everything has become smaller and firmed up.
My doctor told me to expect some more serious muscle mass loss once synthetic HRT starts. We shall see. Staying active in any capacity will certainly help with keeping your physical abilities limber.