In late 2013 I was diagnosed with depression. That in and of itself has been a medical adventure, although I seem to be on the mend, apparently because of CPAP [1]. However, one's state of cycling fitness is not improved by a state of mind that makes one want to hide under the bedclothes all day and eat junk food, especially if the doctor tries Mirtazapine whose side effects include making you sleepy and crave lard.
As such I would reasonably expect to be considerably slower and more easily tired than I used to be, and I am. (Additionally, my overall fitness has been on a slow downward trajectory since 2004-ish when I stopped commuting 110 miles a week and started becoming a middle-aged man).
However, additionally I'm unpredictably extremely weak, particularly uphill. I know a weak rider will struggle more uphill, but (as the best example) it struck me on the Dun Run three? years ago that I kept seeing the same riders because I would pass them on the flat but as soon as the road turned uphill I'd be miserably struggling at walking pace and they'd shoot past me again.
Also, it comes and goes. A friend of mine and I rode the Sightseer this weekend. We got back with only half an hour to spare, because he is consistently slightly slow and I am sometimes incredibly slow - if you ride together of course this makes you slower than either rider alone. Food helps sometimes, but I don't think it's the bonk because I am all too familiar with what the bonk feels like. I joked about this year's Dun Run that drinking a pint of beer every hour kept me going, but coincidence is not causation so I don't know if it was sheer murder after 80 miles _because_ the pubs had shut.
It may be pertinent that about a year ago I was also diagnosed with hypertension which has since been treated with medication; but this weird loss of strength has been going on longer than that and has been pretty constant throughout.
[1] As a side note here, because it may be relevant to other sufferers, in late 2016 a friend of mine at the MRC sent me a copy of a paper to the effect that 90% of patients with depression and OSA report improved depressive symptoms if their OSA is treated. I snored like a fiend, but that's not the same as OSA; got tested, yes, I do have OSA. The NHS then issued me a CPAP machine with astonishing rapidity, and I've been sleeping in Darth Vader cosplay since.
If it works this is extremely attractive as a treatment for the Black Dog since it doesn't fuck with your brain chemistry and also OSA is horribly bad for you in many other respects. If nothing else it has certainly improved my health in that the odds of C murdering me in my sleep are greatly reduced.
