Restoring muscle glycogen

Are only CHOs used to restore muscle glycogen or is there a pathway that involves the conversion of fat/fatty acids into glucose and then glycogen? I did a VO2 max session yday and I ate sweet potatoes with dinner, but woke up this morning with legs that feel empty. Usually I eat some CHO source that is a bit denser (farro or purple rice) but I thought I’d try sweet potatoes after hearing some many good things about them.

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Fats can be converted to glucose but its inefficient and takes more energy than you gain, your body rather uses fat through other fueling processes.
I can’t comment on a ketogenic diet but from what I’ve read I don think your body fuels on glucose primarily either.

I eat plenty of CHOs. I guess my question was in the absence of sufficient CHO intake, are fats converted into glycogen to make up for the deficit? I wish there was a way to measure the quantity of CHOs “burned” during any given training session.

you still restore glycogen stores when short on carbs. you simply can’t expect any supercompensation which is one of the key adaptions performance oriented athletes are seeking.

Even when on a low carb diet with 100-150g/day you see this restoration. However, you will have a higher storage of intramuscular fat, which is a valuable engery source as well.

Different when you’re on keto. There it is suggested that glycogen stores are normalized due to enhanced gluconeogenesis. Furthermore, blood glucose can be synthesised via a variety of other substrates ( https://www.physiology.org/doi/abs/10.1152/ajpendo.00397.2012 ). Therefore, highly fat adapted elite ultraendurance runners to not differ that much w/r to glycogen storage:

grafik
Volek et al 2016

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Thx for link. I’m planning on doing a 2-hr mellow ride today and will consume high levels of CHO postride for tmrw’s hard session. I’ve found that legs “open up” for lack of a better word after easy rides and CHO uptake is pretty good.

To further expand. Gluconeogenesis of the glycerol freed from triglyceride(fat) following fatty acid oxidation. So unless you are already fat adapted such that much of your energy comes from triglycerides you wont get much glycogen conversion.

Yeah. Not fat-adapted. I think I overestimated the CHOs in sweet potatoes and the CHOs used during VO2 max work. Lesson learned.

A VO2 max test will give you energy burned in each zone and on one of the podcasts I recall there is a gaseous exchange test that will tell what you are burning, carbs or fat etc

@tkruger make sure you’re getting PLENTY of hydration, too. It takes a lot of water to get glycogen into the muscle. 1600 kcal of glycogen in the body will amount to over 2 liters of water.