Sudden Muscle Fatigue


I’m a 48 year old TTer and I’ve been working through a medium volume plan. I’ve completed SSB 1 & 2 and am currently in Week 6 of Sustained Build. Everything has been going really well and I’ve been hitting the intervals and seeing a slow but steady rise in FTP.

This week, however I suddenly couldn’t hold power levels that I have been able to do fairly easily previously and ended up bailing on the very first intervals of the Thursday threshold set. I tried again a two days later after a rest day and the same thing happened. I’m not ill and HRV levels are good but my quads are incredibly sore so I’m guessing this is what they call DOMS. It was a bit of shock given how well things had been progressing

I’m planning on taking a couple of days off and swapping things round so next week is the recovery week in the hope I can pick things up again after that. I’ve also got a massage booked and having been wearing compression trousers. Any ideas if this is a good approach? Should I just rest completely?

If anyone else has experienced this kind of thing I’d be really interested to know what worked for you to get through it. Any particular nutrition tips or training / exercise strategies?

Thanks very much for any help


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Eat more carbs and protein. Well seasoned athletes require far more protein to counteract the decline in amino acid utilization efficiency . Upping my carbs intake has changed my whole training experience.

Thanks for the reply. I’ve had a think about my nutrition and you may well be right in that my protein intake is lower that than it should be so will try and get that sorted out. The thing that has been most shocking is how it was a total cliff edge, one day everything was going fine and the next it feels like my body is completely broken.

The pain in my quads in particular is still there, being tender to the touch like they are bruised, even after a day of rest so I’m now thinking that at a week completely off the bike might be a good idea.

42 yrs old. I had the same feeling starting week 5 of GBMV. My legs never even recovered during week 4’s recovery week. I think it was just the accumulation of stress of the first 3 weeks. What I changed going into week 5 (currently in week 7) that made a big difference was fueling as the workout started and midway through (45-60 mins). Also, I Focused on eating more carbs off the bike. I always do a recovery drink, so that hadn’t changed.

Additionally, I think my body adjusted to the stress. Starting GBMV after 12 weeks of Base my body just wasn’t prepared for the intensity. Coupled with an 8% (22w) FTP increase it was rather big and sudden ask of my body.

Lastly, how has your cadence been? I’ve noticed as I fatigue week after week if my cadence drops I’m more sore for the next workout and week.

I wouldn’t do that. I’d at least lightly spin every scheduled training day. At least start each workout and get through the initial warmup. Maybe add +10 mins to the warmup at 80% slowing increasing until you reach 100% by the end of that 10 minutes. Get into the first interval of the workout and THEN make a judgement call. You can always lower intensity, cut the workout short or stop and substitute a recovery ride. I’ve had some of my best workouts when I thought I was too sore to train.

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Yeah the build plans do a lot of high interval work. Depending on the trainer I think the quad pain I was experienced was due to tight hip flexors from how I applied power on the trainer. So, rest and stretch helped me. And back off the high intensity a bit.

Cadence is normally pretty good although does tend to drop off on the last interval or two. I’ve taken yesterday and today off the bike and have switched the plan to have the easier week one week early so will see how that goes. Sun is shining so might be an opportunity to get outside!

I had a similar experience in 2017. Had my highest FTP on the test after the 12 SSB program and promptly crashed in the build phase. Better nutrition was the key to getting back on track with the training and racing. I’ve adjusted even more now after listening to @ambermalika and @Nate_Pearson on the importance of carbs for fueling and prioritizing nutrition around the workouts.

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Really good to hear that you experienced something similar and came out the other side. I watched the podcast with @ambermalika and @Nate_Pearson discussing nutrition (which was by the way very inspiring) and the key does sound like fuelling. In a way it does feel like a bit of a leap of faith to load up on carbs for an 1 or 1.5 hour ride as the whole weight gain thing worries me. I guess the intensity is the thing that drives it and the fact I’m struggling with muscle fatigue is evidence enough that something needs to change. Would you normally take in extra carbs for something like Pettit? Also how long before a ride would you “carb-up”. Thanks again for the replies

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@JonnyBike - As some additional background, I have done quite a bit of training in fasted, semi-fasted and fully keto-adapted states. And being a bit of data nerd I measured my blood glucose and my BHB (the ketone) as indicators of the extent of fat burning during a ride so I have my n=1 comparison baseline. Also - I’m 54.

What is now working for me in terms of strong training sessions and successful body recomposition aka fat loss has been to track my macros using the Lose It app. I target between 200 to 500 kcal/day net deficit relative to what LoseIT thinks my calorie intake is to lose at a rate of 0.5 lb/week while aspiring to my daily Protein and Carb targets. This includes the exercise calorie count. I’m not particularly worried if the calorie deficit is more as long as I’m eating enough to cover 75% of my protein target and 50% of my carb target depending on the intensity of the workouts planned. The main control lever then is the fat levels and how I feel and how I am recovering. This approach has me down 20lbs in 13 weeks and very a successful off-season training block.

To your specific question to fueling for rides like Pettit or even Baxter, the general answer is no if I paid attention and ate my sweet potatoes and grains as planned for breakfast and lunch. If I missed or felt low energy then yes I’ll pop a couple of dates or banana or use a a sports drink like Skratch or OSMO. BTW- dates or date rolls are a great carb source because of the fiber and other nutrients.

For higher intensity and longer endurance efforts, then yes I have moved to the fueling camp but since I include these in my daily calorie count I can maintain my targets overall by adjusting the pre/after ride nutrition. For example I have Baxter+2 planned for today and that’s about 1000 kcal for me, so my breakfast was about twice as big calorie wise than on a 500 kcal workout day because typically after a long endurance ride I’m just not that hungry.

Has this translated to race day? I think so. I did a fatbike race on Saturday and spent 48 minutes of the 2 hours above threshold and 6 minutes at threshold (a very punchy course). Furthermore, I maintained a very consistent power and lap time across the 10 laps although I backed off a bit in the second hour but this was small compared to precipitous drops in power in previous races similar to this. I fueled more the days leading up to the race, race morning and during the race in terms of carbs than I ever have for any race. It was a very different race experience but even more was the post race experience. I was not wiped out from a 244 TSS (IF 1.09, VF = 1.27) effort (yes I know it exceeds 100 TSS/hr - but they didn’t race fatbikes in the snow when TSS was invented ) and I did not have any soreness the following day or the next. I did a 60% ride the next day and my HR stayed down just like it should for such a ride. Looking back at past rides, when I rode that hard my recovery was never that good when I didn’t freely fuel with carbs. And no cramps or localized significant muscle fatigue.

I’m now enthusiastically and confidently looking forward to starting my Base-Build-Specialty sequence for my A race. For me, dialing in the nutrition as a whole day approach has been the training breakthrough.

Good luck and here’s to great training.

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Thanks very much @ExpertOrBust for the detailed reply. It’s so helpful to learn from the experience of others and really is appreciated.

Reading through your post it’s starting to become very apparent that nutrition is the most likely cause of my woes. I do eat very healthily and gave up alcohol just over three years ago but my macros and I think crucially timing of eating is way off. (too many carbs at the wrong times!) Up until September last year I was logging all my food on MyFitnessPal but since then I’d say my protein intake has dropped when at my age it should be rising. In addition my weight has crept up a KG or two so something has to change.

With the deep pains in my legs persisting I’ve taken a complete rest week and have started logging my nutrition again, making sure I get enough protein every day (1.7g/kg). On non-training days the carbs tend to look after themselves.

Like you I’m going to join the fuelling camp and for the training days will start going with the advice of @ambermalika and make sure breakfast plus what I eat on the bike the equals the total calorie expenditure for the ride. This is slightly complicated by the fact that I train early morning (0530) but I’m thinking it should be achievable with some high GI stuff like carb drinks, dates, gels etc followed by a 4:1 protein/carb drink and something like a boiled egg afterwards. For the rest of the day I’ll just revert to my non training day diet, keeping an eye on protein whilst trying to not over doing the carb calories!

The TT season starts for me in about 5 weeks so hopefully a change in strategy will help make the next few weeks of training as productive as possible. Best of luck and wishing you every success with your racing and thanks again.


Morning training is an extra challenge. There are some other threads on forum that cover strategies for that.

Please let us know how it goes!

Will do. :+1: :blush:

Thanks for watching the episode! Fueling is so key, and is often the culprit of bad legs (even seemingly out of nowhere). As interval intensity increases through a build phase, your need for CHO intake will also increase. Many athletes can get away with sub-optimal fueling for base miles, until intensity begins to increase and “out of nowhere” they feel terrible. Our bodies are amazing at adapting, so often the body will continue to adapt to the new loads under the same fueling strategy … until it can’t anymore. That’s where we perceive the drop-off as “out of nowhere” when in fact the body was experiencing it as a consistent, growing concern. To your question regarding fueling, you can use total kcal or kJs burned during a workout as your guide for intake (e.g. higher intensity = higher kcal/kJ = more CHO). If you try to match your pre-workout and during-workout CHO intake to equal total burned during the workout, and you have a recovery drink within 30min post-workout, you’ll be amazed by how much better you’ll feel. Your recovery will be off the hook!

For early morning rides, it can be hard to eat a few hours ahead of the ride, so just focus on eating something easy with simple (easily digestible) CHO just before getting on the bike (toast with jam or honey), then having some CHO on the bike (gels, chews, whatever you like, plus hydration mix). I’d suggest starting with the equivalent of a gel (100kcal) every 30 minutes (e.g. 10-15 min into the ride, then 40-45 min in, etc) and see how your stomach feels. It might take your GI system a while to adjust/adapt. This is an important feature of your training, though, as training your body to accept race-like fuel in training will leave fewer “unknowns” on race day.

I read in one of your other posts that you’re 5 weeks away from TT season. Body composition helps for sure, but keep in mind that for TTs, absolute power is king. In other words, watts/kg is less important (unless you’re doing hillclimb TTs) than straight-up watts. I suggest focusing on increasing the wattage part of that equation, by fueling your efforts to get the most out of each workout. You can create safe/sustainable caloric deficit through your other meals in the day if needed (focus on nutrient density/macros to get what you need). Be patient with the numbers on the scale, and trust your body to make the adaptations you’ll need (including body comp). Don’t stress too much if you’re not at race weight in 5 weeks; give your body the fuel it needs and trust it to optimize your physiology.

Regarding your leg pain, it could definitely be DOMS (which can be surprisingly painful), but be aware that cyclists can also be at risk for deep-vein thrombosis. I know several pro cyclists who have had these. If you feel a sensation like a sustained muscle cramp, or you notice lower-leg swelling/edema, check with your doctor. They can do what’s called a d-dimer blood test, which can rule out a blood clot.


Hi @ambermalika,

Thanks so much for taking the time to put together such a detailed reply to my question. It’s really appreciated.

I had the same issue last season with “sudden” muscle fatigue, with the only difference being it happened two weeks before my A race and I subsequently missed my targets and got quite down about things. After that the whole season entered a bit of a negative spiral as I convinced myself I needed to train more, and the worry over weight gain meant I was restricting calories as well which, knowing what I know now, was a toxic mix. It was actually this experience that convinced me to give TrainerRoad a go to try and bring about some more structure to my training. I never considered for one minute that I might be running on empty which seems crazy when you look back!

Following a week off my leg pain has subsided and as of this last weekend I’ve started implementing the (pre-ride kcal) + (during ride kcal) = (Total kcal burned). I know its early days, but it feels so much better already, particularly the recovery side of things. Zone 2 feels like Zone 2 again and threshold is once again obtainable! Fortunately, I do seem quite lucky in that I have a bit of an iron gut and so far, have avoided any GI distress, despite the big increase in carbs.

I can’t thank you enough for the advice which I’m sure is going to have a massively positive impact on not only my cycling but also my mental relationship with food and training. I really hope to see you with @Nate_Pearson @Chad and @Jonathan again on the podcast soon.

All the best



I had muscle fatigue for 10 months. I was so weak. It was really horrible. Doctors didn’t know what was wrong with me. I am a 45 year old woman.
I had my ferritin (iron storage) levels checked and I was a 19
The range is 16 to 235 so 19 is very low.
I take floradix in the morning and at night and I feel soooooooooooo much better. Now my ferritin level is 24. Slowly moving on up. YOu can check your ferritin blood test for 30 bucks online. Your lab works.
My life is back! I am so happy. Please write me if you feel bad I know a lot of answers to lots of things …

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Very similar experience here. First foray into structured trading due to our first baby coinciding with discovering crits end of last year. SSB MV went well, SP Build I went okay, then into II… just nothing. Empty tired legs. Raced last weekend and felt so flat. Also contending with 4:30am workouts.

Looking back nutrition may have been the culprit. When it came to 90min rides in SSB I was meticulous about eating, waking up an hr early to shove something in my face while still in bed, not avoiding the carb drink (not a fan of sugary things in general). Given the frequency of >60min rides in Build I didn’t maintain this focus. It was a lot easier when you had all week of doable work then one O/U session where focus was required