On a mountain bike I had been working my way to minimize the time it takes me to do a 25-km round-trip.

Then on a road bike I have been trying to do the same for a 40-km round-trip.

My objective on both was to cycle one day, rest the next, then cycle again.

All was well for the 25 km ride. I didn't even need to take a water bottle. Drinking after the ride was enough. For the 40 km ride I was able to maintain the same skip-a-day rhythm as long as I was not pushing myself, though I needed to drink about 1 litre midway, at 20-25C (68-78F). Once I started to race against my preceding time, something went very wrong. After 48 hours I feel too lethargic to hop again on the bike. It doesn't even get better after 72, and barely after 96 hours. I need almost a week to have recovered enough to repeat.

After some searching, the best I've been able to understand is that my 48/72/96-hour lethargy approaching a state of sloth may be caused by glycogen depletion. On multi-day rides, cyclists ought basically gorge themselves before, during, and after with carbs, but I'm not doing multi-day rides.

Hence, I'm guessing, it was a mistake to continue eating the same carb-conscious diet. My calculation for eating steak-and-vegetables, chicken-and-huge-caesar, chickpeas-and-tomatoes at lunch/dinner was that the steak/chicken/chickpeas anyway have large carbohydrate content, in addition to protein, and so I can skip the side of rice/potatoes/pasta, being content that breakfast consists mainly of carbs—bread/oatmeal/..

I was about to experiment with the following classical diet. Eat a (large) plate of pasta 2-3 hours before the ride; eat some more carbs during the ride (2 croissants); then eat protein and vegetables after the ride. The carbs before/during the ride satisfy the needs of the ride, and the protein contributes to muscle repair after the ride.

But this traditional thinking has "largely fallen out of favor as it can also lead to excess water weight and digestive issues."

I realize (I'll soon be patronized and) that 40km is little more than a warm-up for the serious folks. There are several ideas already posted here for longer rides: Gorge on slow carbs post ride, replenish with fast sugars during the ride, snack mid-ride on boiled potatoes + oil + salt; and only one that I could spot for short ones: don't just drink water, drink gatorade. In terms of taste, If find this combination particularly appealing. But rather than experiment on myself over much of the season, I thought I'd ask.

If cycling is seasonal in your area (it's too cold to cycle outside October-to-early-March in my area, and I get bored on a stationary bike after 15 minutes, so I switch to squash and skiing in winter), have you nailed down how to adjust your diet to recover as soon as possible, perhaps even after one day not two?

  • 4
    For most people, the ability of the body to store up glycogen grows as it is "challenged". If you repeatedly (at a 2 or 3 day interval) exercise to almost the point of glycogen exhaustion then the body "learns" to store more glycogen. But beware of exercising beyond that point, as this leads to "ketosis" -- the build-up of ketones in the blood, and this is quite debilitating and can even lead to injury. Commented Jun 7, 2020 at 16:13
  • 3
    I'll just comment that an all out 40 km effort every other is a lot for a beginner. From what I've heard, something like 10 km time trial once per week and way more base kilometers would be more appropriate.
    – ojs
    Commented Jun 7, 2020 at 17:21
  • 4
    Once I started to race against my preceding time, something went very wrong. After 48 hours I feel too lethargic to hop again on the bike. It doesn't even get better after 72, and barely after 96 hours. I need almost a week to have recovered enough to repeat. Sounds a lot more like burnout from too much training than glycogen depletion or bonking on a single ride. FWIW, riding hard like that all the time right at your threshold is a great way to get good at being mediocre. Getting FAST really requires riding a lot at about 1/2 to 3/4 threshold power to build your pure aerobic power. Commented Jun 7, 2020 at 18:11
  • 1
    I get the impression that you're looking for a way to instantly improve your stamina/strength/speed. It doesn't work that way -- you have to do it gradually. Commented Jun 7, 2020 at 18:14
  • 3
    "... the steak/chicken/chickpeas anyway have large carbohydrate content ..." - I'm not sure how you meant this exactly, but be aware that steak and chicken contain basically no carbs. Chickpeas, quite a bit. Steak and chicken, none.
    – marcelm
    Commented Jun 8, 2020 at 19:19

3 Answers 3


This is most likely a mixture of fuelling and trying to do too much too soon.

It sounds like you routinely eat a fairly low carb diet, which is not in itself a bad thing, but will mean that it's unlikely your glycogen stores are ever more than partially filled. This is not a problem at all during low intensity exercise, but when exercising at high intensity for a prolonged duration (racing yourself for 40km), its a recipe for poor performance and and bonking/hitting the wall. When you fully deplete your glycogen stores in this manner it is normal to take several extra days for recovery.

In terms of your choice of workout, it is also likely you are creating a training load that is far too high for you to handle. Going flat out for 40km is something an experienced cyclist might do once a week at most - and even then not for a prolonged period. And after completing such an effort, they would expect to feel sore and sluggish for several days afterwards and limit themselves to low intensity riding.

Assuming you want to continue trying to test yourself over 40km, you might like to consider having much more structure in your riding. As an example you could do something like the following:


  • 30km ride with 15km hard
  • 40km easy
  • rest day
  • 30km ride with 15km hard
  • rest day
  • 60km easy
  • rest day


  • 30km ride with 15km hard
  • rest day
  • 60km easy
  • rest day
  • rest day
  • 40km max effort
  • rest day

This still gives you an average of a ride every other day. It includes some shorter and harder efforts which whilst very hard in their own way, will not create nearly as much training load. And you have some longer rides to build your engine.


It's been a while since I researched this, so don't take it as gospel, but ...

There are several stages in the sequence toward metabolic exhaustion:

When you first start to exercise, the muscles (other than the heart muscles) burn "blood sugar" -- glucose. This provides instant energy, so it's always circulating (until the supply is exhausted). Blood sugar can be replenished from the digestive system and the liver, but the digestive system tends to shut down when you exercise hard, and the liver cannot pump out blood sugar very rapidly.

So, after a few minutes of reasonably intense exercise, the muscles begin depending on glycogen. Most of the glycogen in the body is stored in the muscles, which is good, because when one, eg, lifts a 500 pound barbell the tension in the muscles cuts off the blood flow, so that the muscles are starved of glucose from the blood and must depend on their own glycogen stores. (There are several genetic disorders -- McArdle's syndrome, et al -- where the muscles cannot break down glycogen, leading to a number of symptoms, some rather dangerous.)

Some glycogen is also stored in the liver, and, when blood glucose levels drop, the liver will begin to convert this glycogen to glucose.

So much of the ability to exercise for extended periods is dependent on glycogen stored in the muscles, and when you deplete that glycogen you "hit a wall". But regular exercise, sufficient to burn most of your blood sugar and thus trigger the glycogen mechanisms, will tend to cause the body to store more glycogen in the muscles (in between exercise sessions).

When glycogen is depleted, the muscles will attempt to burn the last bits of glucose in the blood. But this is bad for the brain (which does not have its own glycogen stores), so the liver kicks into high gear and starts converting fat into ketones. The muscles and brain can "run" on ketones (and, interestingly, the heart can ONLY run on ketones), so you get an extra burst of energy.

But this burst of energy comes at a cost. The high levels of ketones produce headache, fatigue, dizziness, insomnia, and nausea. Acetone in the blood produces a sort of "fruity" smell to the breath. I can attest that it takes several days to recover from a major episode of this condition.

  • 1
    It's actually more complex than this - the more you exercise, and the longer each exercise is, the more energy your muscles get directly from burning fat - and fat is the most O2-efficient and by far the biggest tank of "fuel" your body has access to. That's why you have to ride long rides below your aerobic threshold to get FAST - you won't develop the ability to burn fat if you're right at your aerobic threshold for an hour at a time all the time - you get really good at being mediocre. See us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources for some in-depth discussion. Commented Jun 10, 2020 at 1:41
  • This one's also really good: nutritionandmetabolism.biomedcentral.com/articles/10.1186/… The problem with studies like that is the test subjects do exercises like "5 times 4-min intervals at 60 % Wpeak (~95-100 % of heart rate reserve) interspersed with 2 min of rest" or maybe half an hour. That's not going to be very useful for figuring out what happens for cyclists training to get faster on rides that last 3-4 hours or longer, and for pros day-after-day for stage races. Commented Jun 10, 2020 at 1:42

I run on carbs, so my diet is very different to yours. But plenty of people do ride low carb, even keto. It's a conscious lifestyle decision for them though, and others only have carbs at all towards the end of a long ride. It takes time, effort and commitment to adapt to that, and it's not for everyone.

Your typical daily diet as described in the question is comparable to what low-carbing friends would eat. Unless you've put a significant source of carbs on them, the steak and chicken will have very little carbs; the biggest source is likely to be the chickpeas. You probably exhausted your glycogen reserves on the longer ride, and maybe would have done whatever your diet. Your strong thirst is compatible with burning fat, which takes water.

You don't have to overcompensate for your suffering this time, by going to a carb rich diet, if you don't want to. Simply adding a carb-based snack (e.g. a banana) half way through may be all you need. Another thing that may help is a source of protein during the ride. Certainly I ache less after a fasted ride by starting a protein drink after about an hour, and that was more noticeable when I first started fasted training (a similar distance to your rides, and quite possibly with a similar level of carbs in my system).

Some riding through winter would be helpful unless it's actually unsafe due to ground conditions etc. Many people routinely ride through severe winters

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.