xfimpg

Hi

I've Googled this question but haven't found the answer so I thought I would post it here.

Does anyone know how long it takes for the body to digest and store carbohydrates as glycogen?

For example, if you eat a bowl of pasta for lunch today, how long can you expect those carbs to be stored and made available for future use?

This question pertains more to solids as opposed to liquids, i.e. Gatorade.

Thanks

gregf83 

Glycemic Index is a pretty good measure of this.

Carbonfiberboy 

And assuming that your glycogen is depleted, all your carb calories will be stored as glycogen as soon as they are digested. When those stores are topped up, it gets stored as fat. So with high GI foods, pretty much right away. Total glycogen calories stored depends mostly on muscle mass. Bigger people with bigger muscles store more. One sees 2000 total calories thrown around a lot, though small people might only store 1000 or so. But 2000 calories is a lot. It takes a while to eat that many carbs. After a very depleting ride, when I'm having trouble walking, I'll space it out over several hours. But for sure, if you do it right and you've trained to do it, you'll be ready to go again the next morning. Your muscles and other systems however, may not be. But that's one of the reasons that good stage racers are so special.

Obviously Gatorade, running only 200 calories/qt. doesn't begin to have the calories to do much for this restoration. Stout is a lot better than that. In general, liquids are faster than solids, which is why you see special recovery drink mixes. Many of them have maltodextrin, which has the highest GI, as the main ingredient.

Be all that as it may, most people don't get very depleted on an ordinary ride.

xfimpg

Thanks, I found this to be very informative. I certainly identified myself in the "spaced out".
As a heavier mountain bike rider (6-1 and 195 lbs), I tend to need a protein bar or similar (excluding gatorade) every hour to hour-and-a-half or else I feel like I'm riding on fumes. And this is after a good-sized breakfast. I've often wondered if it was because my glycogen stores are smaller than average or I just burn more because of my heavier weight. I think putting it all together now it would be the latter.

gregf83 

Your glycogen stores should improve with fitness. While you're riding though it's better to stick with carbs. The protein isn't going to help with performance.

xfimpg

Sorry, i didnt mean strictly protein, but a protein bar like Builder's Bar - 20grams of protein and 30g of carb, not excluding the Gatorade.

Carbonfiberboy 

It's not so much the quantity of your glycogen supplies as it is the access to them and your fat stores. What you are experiencing is normal. This improves with months/years in the saddle, riding long distances. I was just the same at first. I'd die if I didn't eat every half hour. Now I can ride for two hours with neither water nor food. Many riders find they have different protein requirements than other riders. Some riders do fine on pure carbs, others need about 25% protein or 4:1 carb/protein ratio. I'd question the need to consume more protein than that.

Edit: I should have mentioned that "normal" is to consume 100-300 calories/hr. while riding, depending on how hard one is riding. This greatly reduces glycogen use, and can extend glycogen stores for very long periods of time, even days, depending on just how hard one rides.

xfimpg

Again, very informative.

gregf83 

That will give you about 120 useful calories. As Carbonfiberboy mentioned you can absorb up to 300 Cals/hr. The protein is useful for assimilating carbs after the ride during recovery but it hasn't been found to be helpful during exercise.

Pat

I do not think that calories taken in are necessarily available as glycogen immediately.

The reason for this is that even when one eats on a long hard ride, one will eventually deplete the glycogen stores. People riding ultra marathons tend to go at pretty slow paces.

OK, how does one know this?

Oxygen in the muscles is the limiting factor for aerobic metabolism which is what bicycling is all about. Now, burning fat takes twice as much Oxygen per ATP (the chemical energy currency of the cell) as burning carbohydrates. So when your cells are burning fat, they are at essentially half power. This lack of power is a symptom of glycogen depletion.

Now, another explanation could be that one burns the carbohydrates faster on a bike than one can digest them. That could be true also. One gram of carbohydrate equals 3.5 calories. Ten grams would motor you down the road about 1 mile. That is about one small cookie. So could you consume 100 cookies and completely digest them in a century (really low glycemic index)? One could try it. But I don't think I will try it.

beezaur

In this book the author, who is a dietitian, says it takes about 2 days to rebuild your glycogen stores refueling with carbs if you have more or less gone to exhaustion. If you do it with protein or fat, it takes a week or more.

She says for the first hour or so your body doesn't care what kind of carbs you ingest -- they all get processed to glycogen.

Evidently you can increase the rate at which glycogen is made by ingesting multiple types of sugars. For example (and I am going from memory) fructose has one metabolic pathway, glucose has another, and maltose has yet another. Any one pathway only works so fast. But if you take in replenishment with all of these, they work in parallel, allowing you to process more raw calories into fuel for activity. This is more something you would do during activity than in recovery.

In recovery it is normally held that you are better off with slow-acting carbs, like whole grains, fruits, etc. (a mix of healthy foods).

beezaur

When I go that far I don't even metabolize food for several hours. A glass of milk and a nap is about the fastest way through it for me.

xfimpg

Very interesting discussion we have here. Thanks to everyone who has contributed. :thumbs:
Just to add a variable into this, I remember reading the book "Turn Up The Heat" by Philip Gogila, where he presents three body types; protein-efficient, carb-efficient, and duo-type.
As the protein-efficient type, it makes me wonder if that can have an effect on the general functionality of my glycogen stores. By that I'll go on a limb and say that I would suspect that a carb-efficient type may be able to store and use their glycogen stores more efficiently due to their nature of being able to perform endurance sports. The protein-efficient, not so much as they are built for short power, not sustained. As for the duo-type, they are the fortunate ones and can do it all.

Carbonfiberboy 

This is how you do it:
https://www.the508.com/articles/2002/born1.html