Hi Chris
I'm not as sporty as you, I've never done anything competitive apart from the odd 5 or 10k, but I've always exercised and currently work out 5-6 times a week including 2 sessions with a personal trainer, so I like to think I'm fairly fit and I certainly notice changes in my body.
I'm 44 and had a hysterectomy at 41. I took HRT for the first year after and life was great, I felt great and exercised as normal, it was as if none of the problems or surgery had ever happened. Then I started to get the old symptoms again and discovered that the HRT was aggravating my endometriosis, so I now take nothing and I'm in full blown menopause, I get hot flushes, mood swings, VA, the lot. But the killer for me is the night sweats & interrupted sleep, I feel so tired most of the time, and I keep getting headaches which is probably due to poor sleep. Although I do find exercise helps to stave off the headaches.
Like you there are days where I really don't think I'll make it to the end of a workout, and I've also had recent issues with breathing when running. It's almost like I've become asthmatic, my throat feels like it's closing up and I start to wheeze. I've never been asthmatic and never experienced this until a couple of years ago.
I'd like to think I'm still a little young for the fatigue to be due to age, but I guess it's a combination of both.
Glad to hear the HRT is working for you, if I could go back on it I'd jump at the chance.
Kim