Training induced brain fog - solutions?


I’m train approx 10-15 hours per week, which is having significant repercussions on my performance at work (sedentary, regular office hours + a bit) which relies on my mental capability. Does anyone have any suggestions as to what to try to prevent this brain fog? Or do I just not to accept this as part and parcel of being an endurance athlete?

Current routine involves commuting by bike, doing some intervals on my way in (typically sweetspot, nothing consumed during the workout) and then an easy ride home. I rarely end a session feeling glycogen depleted, but often feel empty/fatigued when starting sessions. I eat breakfast beforehand (e.g. two wholemeal bagels with peanut butter this morning) and have a small snack of greek yoghurt with honey after. I then eat lots throughout the rest of the day. I am sleeping ~7.5 hours per night, which is less than I would like but hard to change since it takes me a long time to fall asleep.

Thanks for your input.


See your Doc

I would try to work on getting more sleep as a first priority. Getting 1-1.5 hrs more per night can have a impact on recovery, and lack of recovery is probably where that brain fog is coming from.

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First, is that 7.5 hours of sleep actually 7.5 or are you just in bed for 7.5? Getting into bed, getting settled, browsing your phone, then actually falling asleep, and any time you wake up in the middle of the night for bathroom, etc. can all add up and you may only be getting 6.5 hours even if the time between your “bed time” and your alarm going off is 7.5.

Second, how are you measuring your training? It’s possible that the ‘easy’ ride home isn’t as easy as you think and it’s not allowing you to recover from your proper session like you think it is.

Third, I know you say you’re “eating lots” during the day but it is possible that you are not eating as much as you think you are or as much as you need. If you are not already, maybe track your food consumption for a couple of days to get a feel for it. A couple of months ago my girlfriend would have sworn that she was eating more than enough. But when she started working with a dietitian she was shocked at (A) how little she was actually eating (avg ~1250 cal/day) and (B) how much food she had to eat to get in the required calories.

I had this happen to me when I did triathlon.

If I were you, this would be my approach:

  • download MyFitnessPal and meticulously track calories for a week by weighing my food. I’d want to see if I am eating enough carbs (about 8g per kg of body weight at 15 hours a week).

  • try to get more sleep (of course)

  • see my doctor and tell them I’m an endurance athlete and ask to test my vitamin D levels and iron levels. Both of these can be low in endurance athletes and can cause fatigue. You doctor can then check out other issues like thyroid or I’m sure 100 other things it could be.


I know the feeling, and I think that it’s something one just has to accept if one chooses to do an endurance sport. For me, it happens when I regularly do exercise at high intensity for more than 30min. Caffeine helps me a little, but not as much as reducing exercise to 30min, 3 x per week.

I think this is more common than people realize, because many people have no way of easily measuring their mental performance and don’t notice the deterioration when they’re training for endurance sport. Careers like computer software development and hobbies like chess make it easier to detect.

The most mental energy and clarity that I’ve had in recent years was when I was on a low carb, high fat, ketogenic diet and doing only 3 x 30min intense exercise sessions per week. That diet doesn’t work for me when I’m cycling (due to lack of power when pushing hard), but was great otherwise.

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Have you checked for food allergies? I’ve been gluten free since 2009, but if I ever have a bit I am in a fog.

If I was experiencing a mental deterioration if I did anything more than 1.5 hours of exercise a week I would be looking at everything else in your life as that is not normal. 3 x 30minute bouts of exercise a week is below the standard recommended amounts of exercise everyone should do, and far below what most would consider “endurance training.”

I find I personally feel very tired and lethargic if I don’t exercise in some capacity every day, everyone is different, but I think it is fair to say that a few hours of exercise a week should not be impacting your mental clarity, it should be enhancing it.

Seriously though all the advice here is an N = 1 thing. The sleep recommendation for example can vary from 6 to 9 hours and the need is specific to you and while more is typically better it is not always. You end up fitting your natural amount of sleep into a forced longer window which is counter productive. The calorie deficit will be detected in weight loss. Macro adjustments are also individual. @Nate_Pearson works the carbs others Keto it varies. Vitamin deficiency can be a thing in winter for VitD. But all of these need to be assessed by your Doc not us here. There are also a myriad of other unsavory things that could be leading to this so get a check out and eliminate these.

At the very least get off the bike for a week if it persists it ain’t the bike.


Try a gel 15 minutes before the ride and a sports drink during the ride. You don’t have to bonk to be glycogen depleted.

If you stay asleep okay but have a hard time falling asleep, try melatonin. It has a short half life and IME has no lingering effects. YMMV.

Careful with all of the sleep “advice” on this forum and on the TR podcast. In the attempt to help, it can cause more sleep issues. Regarding sleep I recommend the book or audio book The Sleep Solution by W. Chris Winter. This will clear up any questions regarding sleep and will help you with your “it takes me a long time to fall asleep” problem.

Thanks for all the replies so far! To follow up the suggestions:

I’ve been to the doc and nothing came up - vitD and iron both within the normal range, and tested negative for coeliac so I don’t think gluten sensitivity is likely to be the cause.

Sleep is as reported by a garmin watch (vs time in bed). I would love to sleep more but I find this difficult to implement.

@Nate_Pearson @mwglow15 Thank you for the suggestions re checking my diet, I will give MyFitnessPal a go for a week and report back if I am acheiving the suggested carb intake.

@Nate_Pearson I would be interested to hear what the solution was for you personally? From listening to the podcast I get the impression that you are very thorough about these types of things.

@traversw This has been my own experience as well, that a small amount of exercise is good for by brain, but serious ‘training’ has a negative effect

Any other ideas also very welcome!

Like someone said, you’re getting a lot of n=1 advice here. I have experienced this for many years after hard workouts - I’ve always called them “training hangovers” though actually, they feel great to me because they tell me I really hammered and it is kind of a woozy drugged feeling. I only get them after really hard efforts, so they don’t really affect my work noticeably (to others…).

Seriously though, a big helper for me is good old water - lots of it, both right after the workout, and then starting again in the morning. It might just be a “me” thing, but it takes me from 7-8am in the morning until 1-2pm to get fully hydrated.

How much of a change in training levels/amount is this for you? You might just be tired from training. Happens.

Low vitamin D was an issue, but my brain really didn’t function very well until I upped my carbs. The brain takes lots and lots of glucose.

It was so bad that I stopped training to build TR as I couldn’t think as fast. I don’t experience that anymore with like 3x the volume that I used to do.

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How long is your commute?

Maybe you need to change what you eat. The only carbs I see there are two bagles and a bit of honey. That’s not very much. The brain needs a lot of glucose to function.

The other question is, does the morning commute mess with your body clock? Do you have to get up when you would otherwise still be in bed? Waking up in the wrong sleep phase can leave you tired too.

this does not tell us much. What do you eat and when? Give us examples.

Mito, do you still get the brain fog if you don’t ride to work? Or, what if you ride easy and don’t do any intervals? So, if you don’t ride and don’t get brain fog then it’s probably lack of glucose as the others have suggested.

Here is my brain fog story - I cured mine by quitting milk. I was putting half and half in my coffee all day and my the third coffee I’d start feeling foggy instead of sharp from the coffee. For some other reason, I decided to quit dairy for a while and I noticed that I had zero brain fog. Also after quitting dairy my sense of smell returned and my sinuses cleared up. I can still eat cheese and yogurt as they don’t seem to affect me in the same way. I was also tested by an allergist for milk/lactose and had no problems. I have no stomach problems with milk. Conclusion - it could be a food sensitivity.

I had a very similar issue as an undergrad. Training 10-15 hrs a week and couldn’t focus on homework or in class. Ultimately, I figured it out after years of trial and error because unfortunately these things tend to be so specific to an individual.
As everyone has mentioned, for me it was sleep and eating. I use MyFitnessPal and go back to it whenever I feel I’ve fallen off track. As for sleep, it ultimately comes down to routine. Having a consistent sleep and wake time is crucial but can be difficult. I chose a time to get in bed, then I read. Sometimes I fall asleep right away, other times I don’t, but I always sleep better than just trying to go straight to bed. I found a good way to check if you get good quality sleep at night was to take a single melatonin pill. THIS IS NOT A SOLUTION AND SHOULDN’T BE DONE REGULARLY, but even after using it once I noticed that I slept through the night and had the soundest sleep ever. It was actually strange how alert I was the next day. So I was able to identify that sleep habits needed changing. If you abuse melatonin it will become less effective so you really need to diagnose habits as the root cause.


Thanks for posting although I am not happy you are having issues. To put things in context I am a 53yr old and been riding/racing for 30 years. I am also a slow learner when it comes to reducing brain fog. A month ago I decided I was going to throw everything but the kitchen sink at this issue and see if I can get a handle on it as it really sucks.

In priority order this is what I have done. Again I am slow learner! :slight_smile: 1) I have prioritized sleep over everything else. I am trying everything I can to get 7-8 hours of sleep. Not a large amount for some but way more than the 5-6 I was getting. I have never been a big sleeper so this is a big change for me 2) I am making sure I drink enough water. I am really paying attention to how often I go to the bathroom and making sure I drink before/during/after my workouts. 3) I have started eating more. Quality is always best but sometimes I just have to eat something to make sure I am fueled before and after my workouts . 4) Last but not least is instead of doing more/more/more I have opted to back off of my volume ever so slightly or just bail on a workout and live to fight another day. We all suffer from OCD in some way, or we wouldn’t mindlessly pedal in circle for hours on end! :slight_smile: Sometimes backing off is the best things we can do if we are doing to first three items well.

So far I am seeing great results and seem to have the brain fog issue under control. I can not contribute this to any one of the items I have changed as I think it is a culmination of items.

Again I know these are common sense changes to most but hope this helps is some way!

Best of luck with your training.