Help with sudden loss of fitness

I’ve suddenly started failing workouts in a big way, and am hoping others can offer some advice.

First a bit of history. I’m in the 2nd week of SSBHV II. This is after doing all 3 phases of traditional base HV and SSBHV I. Until now everything seemed to be going reasonably well - modest improvements in FTP and major improvements in endurance. At the beginning of the recovery week I donated whole blood, and used FTPD rather than doing a ramp test for SSBHV II. (Got a 2.5% bump.) I figured that I should accept the bump since the donation as the current block is sub threshold, but definitely intended to monitor things.

The 1st week of SSBHV II went quite well - marking the SS workouts as “moderate”. In hindsight, I should probably have marked the Saturday ride as “hard” as I had some soreness into Sunday and found the long Z2 ride a bit harder than expected. Was still a bit sore on the day off (Monday.) I woke up Tuesday feeling good, and jumped into Great Knott which was a large jump in WL. (7.8 up from 7.2 the week before.) I knew this might be a bit on the difficult side and would not have been upset to not complete it. But I struggled in the very first interval, and took a planned short break in the middle to calibrate the trainer. I then had to backpedal twice to make it through the 2nd interval. 3rd interval was lower in intensity but I could not maintain cadence. At that point I gave up, and let AT do its thing. And if that had been the end of it, I’d not have posted.

On Wednesday I did my low Z2 ride and felt fine. Today (Thursday), AT gave me Antelope +2 which was only WL 5.9. I figured that should be a good workout that should be easy to moderate based upon last weeks rides. I was quite wrong. Finished the first 10 min interval at 94% and was surprised by how hard it felt. I then backpedaled 5 minutes into the 2nd interval and lowered the intensity a few %. 3rd interval still felt hard so backed intensity down to 90% and my legs just had nothing in them. I bailed again, but at least did a bit of Z2 afterwards which felt ok.

I’ve been getting pretty much the usual amount of sleep. No changes in diet. No particular change in stress. I feel reasonably motivated. (About to order my dream “empty nester” bike, and want to justify it!) Although I’m 54, I’ve never needed more than 2 days to recover in the past (and have always done the Z2 option on Sundays). My RHR is pretty much back down to normal after the donation, though still a tad elevated on Z2 rides.

Is this just that the big Saturday ride did more damage than I thought? My spirits are still pretty good, but I’m worried that a three-peat on Saturday will do some real damage to my enthusiasm.

There’s definitely been a podcast discussion around Blood donation and the impact it has on the body. IMO that likely explains what you’re seeing when combined with the ftp increase


Ignoring the blood donation, maybe its not the right approach for you.

“The others do lots of intervals, Sepp very few.”

  • Mirren Zeman, Jumbo-Visma Sport Director

In 2017 I had a large (for me) aerobic base, took a short break in November, and then did SSB 1 HV and finished January 2018. SSB HV is a big ask at any age… I was about your age at the time, finished with a great 2.5 hour climb and then watched my fitness drop for months. Years later it seems I do better with more endurance and fewer intervals :man_shrugging:


It would seem to me that post blood donation might be a time better suited to rest followed by a ramp test. FTPD doesn’t know that you gave blood, so this would set it up to give you an inappropriate bump in ftp

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Don’t ignore the blood donation. It can take weeks to fully recover.


I’m glad to read that the blood/ iron loss was a controlled/ organised thing. Back in 2018 I had a sudden loss of fitness after what I think was a one off blood loss which led to a slippery slope of chronic iron deficiency (all of which caused by an underlying health issue). So as above:

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From basic google search, it seems to take 4-8 weeks for red blood cells to regenerate. Losing red blood cells, you took an FTP hit* but then bumped your FTP based on auto detection.

On top of being in a high volume plan, your FTP is most likely too high, and now the wheels are starting to fall off. It might be a good idea to take a couple days off and then half volume easy for the rest of the week. Then do a proper test before you start training hard again.

*From the EPO / blood doping era, I seem to recall a 10% improvement being reported so maybe we can speculate that you lost 10% from donating.

I’m fine with the theory that it is due to the blood donation. But then why did the first week go so well? Surely one week after donation should have been more impacted than after 2 weeks. I honestly expected the most impact would be at threshold and above which would have made the ramp test very inaccurate for sweetspot. At least I did not do my usual power red donation.

At a non medical educated guess you were using up your lasts reserves of blood iron before they had a chance to replenish. The higher FTP wouldn’t have helped, it probably eventually pushed you over the edge and onto that slippery slope of overtraining. AT alone and no rise in FTP might have adapted fast enough to prevent that overtraining (you’d hope anyway) but I think you’d have to be honest about work outs such as your Saturday one which you marked moderate even though it was hard.

You have successfully monitored things! Now you have first hand experience that FTP (and VO2 max, z2 power, etc) are significantly impacted by your circulating red blood cell mass. You have just done the literal opposite of blood doping.

FTP detection does not know that you’ve knocked off ~10% of your VO2 max, and likely a similar amount of you FTP, from donating blood, so you’re training with an overly high FTP. And that all of your zones are too high as a result. You lasted a week or so of this, which is pretty typical, but now the fatigue is kicking in as you start to overreach, and keep trying to do “sweet spot” efforts that are actually threshold or suprathreshold.

Take a couple days off, then do an FTP test. Expect the result to be much lower than what you’ve been using. It will increase over the next weeks as you generate more red blood cells though.


Perhaps week 1 was your experience directly related to the drop in ftp and subsequent weeks problems were more related to ongoing overreaching/overtraining in the setting of a now inaccurate ftp/tss

OK - took yesterday completely off the bike, and only did a very gentle 1 hr z2 on Friday. Woke up this morning and did the dreaded ramp test. It showed that I’m ~10% down

If it takes O(8 weeks) to recover, I’d have thought most of the recovery would happen in the first 3 weeks. I.e., I had imagined an asymptotic recovery rather than something linear. Oh well.

Another minor data point: last weekend I had cleaned/lubed my chain, but noticed that the tire was somewhat squeaky when I put the bike back on the wheel-on trainer. No amount of adjusting did much. Then, this morning after the ramp my wife complained about how bad the basement smelled. After we determined it was burnt rubber rather than o-de-moi, I decided to clean the roller with isopropyl. That did nothing, so I decided to replace the tire. All quiet again. (I could not find a trainer tire for my 650c wheels, but have found my usual tires last quite a while on the trainer.) The “worn” tire did not have the squared-off look that I see on worn tires out on the road, but rather was just very smooth and round. Would even squeak as I rubbed my thumb on it. Any guesses as to how much power could have been lost due to the tire? I am not going to retake the ramp to find out, but will just bump up the intensity if I find the next workouts too easy.

Thanks all!

Hey @tomclune not sure where in the world you are but, where I am every plant species known to man is blooming. Allergens are high. I’ve had a good season but, just this week noticed a pretty big dip in energy. I have a weird lump in my throat when I go hard. Sort of fatigued (sleepy) with good rest etc…I’m riding less than normal so, I’m chalking it all to nature. Just another opinion to contemplate.

East coast (Maryland). So it is allergy season here, but I’m almost exclusively indoors and not suffering.

Are you using the power meter of a wheel on trainer - or do you have a PM on the bike? Changing the tire, its pressure, and/or adjusting the tension of the trainer are all sources of variability for power measurement.

In any case, it feels like you’re seeking every marginal justification to have your FTP be higher. I would stop measuring your fitness “loss” to the value of your FTP and go and ride outside on a route you know well, by yourself. You’ll know if you’re fitter if you’re honest with how you feel.

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Sure they all could have an effect, but I would bet dollars to doughnuts that blood loss + overtraining played a much larger role

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Yes - only have power from the trainer.

I had been feeling the joy of knowing I’m getting stronger from just increases in PL. That’s the larger frustration here than the FTP. Needs to get a bit warmer before I do outside rides.

I’ll report back tomorrow on my now much easier SS workout…

I have no experience with overtraining until now. I’d always assumed it was a much more cumulative thing that came on gradually.

Hoping that I don’t get any more experience with it. :grin:

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Just an update for those that are curious. When I woke up this morning AT tried to adapt Black Lassic (SS 5.9) to something that was 4.2. In the past, I’ve consistently accepted AT’s changes, but at the new lower FTP, I knew that Black Lassic would be quite achievable. And indeed it was:

I rated it moderate, but gave some thought to calling it easy. I thought I might even increase the intensity in the 2nd half, but managed to restrain myself.

Unfortunately, AT still wants to adapt my remaining workouts down to ~ PL 4’s, so I’ve rejected those as well. Hopefully after a couple of surveys marked as “moderate” for high 5 PLs, the system will get back on track.

It will not. It’s my experience AT expects SS to be moderate-hard no matter the PL. I’d just choose a harder Alternate workouts until it feels right. This is what I’ve done all through SSBHV and SustainedPBHV when the ramp rates were too easy.