Unexplained fatigue mid-block
44M, targeting Amsterdam Marathon (18 Oct) — unexplained fatigue mid-block, looking for input. All bloods came back as normal.
Background: Started running mid-2024. First marathon Edinburgh May 2025 in 3:23 (tough final 10k with ITB issues and wind). Current block is a 24-week Runna plan, now ~8 weeks out.
Things seemed to be going fairly well with the plan until I returned from holiday (week in Greece, managed around 40k to keep me ticking over). I felt like I was making progress, Vo2 Max (Garmin) climbing to 61 etc.
Then what happened: Following the holiday I ran a 5-mile TT (31:24 for 5 miles), followed by a couple of 13k easy runs, then six days later a 23km progressive long run that fell apart badly.
Session was 5k conversational / 6k @ 4:45 / 6k @ 4:35 / 6k @ 4:10 — I blew up during the 4:35 block and finished on 5:30s feeling completely empty. Easy pace was already costing 8–12bpm above baseline from the first kilometre.
I was pretty surprised, as while I expected the session to be reasonably taxing, even the final 4.10 section was below my HM pace.
Anyway, that was just under a month ago. The first week following the blowup was rough, all runs felt tough, with my HR on easy runs around 15bpm higher than usual.
Also, my quicker paces were not accessible – felt like I had to empty the tank to do 300m at 4m km pace!
The following week felt a little better, then after around 2.5 weeks my easy runs were back to a more typical HR (although perhaps still a few beats above where i'd expect).
I ran 31k and 44k in the weeks that followed the blowup, all easy pace. Then last week I did 73k, again all easy, with the exception of a 5k slightly above target marathon pace during a midweek run.
I finished the week with a 27k easy run on Sat, feeling good afterwards. Took Sunday off, then went out for an easy run yesterday – again the HR was about 10bpm above what i'd expect and easy pace felt noticeably harder than it should.
I followed that today with a 15k, including 5k ish around marathon pace. It felt better than yesterday, but HR is still a bit high and the level of effort to maintain around 4.25 pace seemed too high.
During the last month my predicted Vo2 has dropped from 61 to 57.
While I'm not completely emptied like I was at the end of the last month, I'm still not quite feeling 100%. And it seems that my recovery from longer runs is still slower than I'd hope/expect.
With that in mind I was curious if anyone has similar experiences? Does sound like it could be over training? I've included a table of my monthly mileage below, which is around 28% higher than the previous 12 months, I didn't think that was excessive. However, I have just realised that the month I blew up was my highest ever at 264km.
Anyway, for the moment the Runna plan is out the window and I'm sticking mostly to easy paced stuff to try and keep the mileage up, but feel like I'll have to incorporate quality faster sections again if i'm to approach Amsterdam with any confidence.
Would love to hear your thoughts, especially anyone who has experienced similar issues...
| Month | Distance |
|---|---|
| Aug 2025 | 116km |
| Sep 2025 | 173km |
| Oct 2025 | 148km |
| Nov 2025 | 141km |
| Dec 2025 | 72km |
| Jan 2026 | 227km |
| Feb 2026 | 132km |
| Mar 2026 | 138km |
| Apr 2026 | 116km |
| May 2026 | 194km |
| Jun 2026 | 220km |
| Jul 2026 | 264km |
| Aug 2026 (to 18th) | 138km |