Fruit as a post workout carb - no good?

[Roush]

We all know that taking a fast acting protein post workout along with a fast acting carbohydrate is beneficial . the carb will spike insulin, raise blood sugar, and create an anabolic environment and glucose will be in the blood stream ready to be driven (along with water and nutrients) into the muscles and fill up the muscle as glycogen stores.

some people use just fruit as their post workout carb . however, I have heard that fructose (fruit sugar), is NOT able to be stored as glycogen in muscle cells, it is ONLY able to replenish energy stores as glucose in the liver. Therefore the whole idea of the carb being used to replenish the muscles is completely lost if you use fruit as a post workout carb.

any diet pros know if there is anything to this idea ??

 

[halfwit]

We all know that taking a fast acting protein post workout along with a fast acting carbohydrate is beneficial . the carb will spike insulin, raise blood sugar, and create an anabolic environment and glucose will be in the blood stream ready to be driven (along with water and nutrients) into the muscles and fill up the muscle as glycogen stores.

some people use just fruit as their post workout carb . however, I have heard that fructose (fruit sugar), is NOT able to be stored as glycogen in muscle cells, it is ONLY able to replenish energy stores as glucose in the liver. Therefore the whole idea of the carb being used to replenish the muscles is completely lost if you use fruit as a post workout carb.

any diet pros know if there is anything to this idea ??

Why can't a simple sugar be stored as glycogen? All glycogen is from glucose (ok, a few exceptions), which is converted from any carb source.

But then again, I don't put a ton of stock in the "golden hour" theory post workout either.

 

[Roush]

yeah you'd think glucose is glucose,, if its in the blood then the body stores it where it wants , glycogen in muscle if it wants. just heard that fruit sugar 'fructose' was a bit of a different animal and was unique in the way the body uses it. I have no clue why that would be though

 

[halfwit]

yeah you'd think glucose is glucose,, if its in the blood then the body stores it where it wants , glycogen in muscle if it wants. just heard that fruit sugar 'fructose' was a bit of a different animal and was unique in the way the body uses it. I have no clue why that would be though

I've never heard of any difference beyond glycemic response. I can tell you that I do know the monosaccharides are essentially the same in how the body treats them. Fructose, glucose, lactose, sucrose, etc. This would be where Zilla comes in and educates us all of course, as I'm not able to do any looking through studies right now.

 

[3J]

I've never heard of any difference beyond glycemic response. I can tell you that I do know the monosaccharides are essentially the same in how the body treats them. Fructose, glucose, lactose, sucrose, etc. This would be where Zilla comes in and educates us all of course, as I'm not able to do any looking through studies right now.

u know how all these iifym guys say a carb is a carb???? lol...

here you go guys, this is why we do not have fructose for post workout reasons

Ann Nutr Metab. 1987;31(2):126-32.
Effects of glucose or fructose feeding on glycogen repletion in muscle and liver after exercise or fasting.
Conlee RK, Lawler RM, Ross PE.
Abstract
In athletics, muscle and liver glycogen content is critical to endurance. This study compared the effectiveness of glucose and fructose feeding on restoring glycogen content after glycogen was decreased by exercise (90-min swim) or fasting (24 h). After 2 h of recovery from either exercise or fasting there was no measurable glycogen repletion in red vastus lateralis muscle in response to fructose. In contrast, glucose feeding induced a similar and significant carbohydrate storage after both depletion treatments (8.44 mumol X g-1 X 2 h-1). In the liver, following 2 h of recovery, the rates of glycogen storage were similar after either glucose or fructose ingestion, but fasting caused a greater rate of repletion (83 mumol X g-1 X 2 h-1) than exercise (50 mumol X g-1 X 2 h-1). After 4 h of recovery fructose-fed exercised animals had the highest glycogen concentration (165 mumol X g-1) followed by the glucose-fed exercised group (119 mumol X g-1). These values were 50 and 36%, respectively, of that measured in the normal-fed liver (327 mumol X g-1). In contrast, liver glycogen values in the fasted group decreased between the 2nd and 4th hour of recovery in response to both feeding regimens. From these results we conclude that fructose is a poor nutritional precursor for rapid glycogen restoration in muscle after exercise, but that both glucose and fructose promote rapid accumulation of glycogen in the liver.

PMID: 3592616 [PubMed - indexed for

 

[3J]

now its a question of whether or not you think you need rapid glycogen restoration post workout... or the whole "anabolic window" argument

 

[Mrrippedzilla]

It's important to remember that fruit isn't made up of only fructose and actually has a nice mixture of carb sources (varied ratios depending on which fruit we're dealing with)....

So with that said, if rapid glycogen replenishment is the goal then you could utilize a 2:1 ratio of glucose/fructose postworkout in order to take advantage of the fact that these 2 utilize different transporters and that this should allow faster rates of resynthesis (fructose CAN replenish muscle stores, it's just not very good at doing it solo).
This started off as just a theory I had based off my understanding of carb metabolism but their is some evidence to support it:
Postexercise muscle glycogen synthesis with combined glucose and fructose ingestion. - PubMed - NCBI

Of course most people know that I don't believe in carb timing (I've had clients rely on fruit as the main carb source through prep before)...
Or the need to replenish glycogen immediately post workout (unless your training again that day)...
Or the "anabolic window" (proven to last around 24-48hrs....window my ass)...

So most of this is just mental masturbation to keep me occupied from what I should really be doing (muscle cell biology refresher...yay...).

 

[Roush]

so are you telling me , if hypothetically speaking there really was a 1 hour 'anabolic window' post workout for muscle glycogen replenishing .. that eating ONLY fruit post workout would probably not be the best choice ,,,, but that adding in something like a white bagel may be better ??

 

[Mrrippedzilla]

so are you telling me , if hypothetically speaking there really was a 1 hour 'anabolic window' post workout for muscle glycogen replenishing .. that eating ONLY fruit post workout would probably not be the best choice ,,,, but that adding in something like a white bagel may be better ??

Sure, hypothetically speaking if your body decided to close those glycogen doors after an hour because, you know, why not, then the bagel ftw

 

[synonymous]

I may be way out of my field so please correct me if I'm wrong:

Fruit is good at restoring liver glycogen but less so muscle glycogen. During the day, before training, you're using mostly stored liver glycogen so getting your carbs from fruit is good. However, post-exercise you are both liver and muscle glycogen depleted and would be better off using something like dextrose or waxy maize, or a white bagel.

 

[Mrrippedzilla]

I may be way out of my field so please correct me if I'm wrong:

Fruit is good at restoring liver glycogen but less so muscle glycogen. During the day, before training, you're using mostly stored liver glycogen so getting your carbs from fruit is good. However, post-exercise you are both liver and muscle glycogen depleted and would be better off using something like dextrose or waxy maize, or a white bagel.

Relying on starchy carb sources (from real food) is a good idea if the goal is glycogen replenishment; my original post intended to demonstrate that this doesn't necessarily mean you need to avoid fructose postworkout because their is no "window" or "carb timing" to worry about.

To illustrate this further, here is a study where one group consumed 165g of fat postworkout (fat should slow down glycogen synthesis right...) and, when compared to the low fat group, muscle glycogen stores were the same 24hrs later -
Adding fat calories to meals after exercise does not alter glucose tolerance. - PubMed - NCBI

 

[Roush]

Sure, hypothetically speaking if your body decided to close those glycogen doors after an hour because, you know, why not, then the bagel ftw

bold and underlined -- point well taken; yeah, why the hell would your body want to do that

 

[Megatron28]

u know how all these iifym guys say a carb is a carb???? lol...

here you go guys, this is why we do not have fructose for post workout reasons

Ann Nutr Metab. 1987;31(2):126-32.
Effects of glucose or fructose feeding on glycogen repletion in muscle and liver after exercise or fasting.
Conlee RK, Lawler RM, Ross PE.
Abstract
In athletics, muscle and liver glycogen content is critical to endurance. This study compared the effectiveness of glucose and fructose feeding on restoring glycogen content after glycogen was decreased by exercise (90-min swim) or fasting (24 h). After 2 h of recovery from either exercise or fasting there was no measurable glycogen repletion in red vastus lateralis muscle in response to fructose. In contrast, glucose feeding induced a similar and significant carbohydrate storage after both depletion treatments (8.44 mumol X g-1 X 2 h-1). In the liver, following 2 h of recovery, the rates of glycogen storage were similar after either glucose or fructose ingestion, but fasting caused a greater rate of repletion (83 mumol X g-1 X 2 h-1) than exercise (50 mumol X g-1 X 2 h-1). After 4 h of recovery fructose-fed exercised animals had the highest glycogen concentration (165 mumol X g-1) followed by the glucose-fed exercised group (119 mumol X g-1). These values were 50 and 36%, respectively, of that measured in the normal-fed liver (327 mumol X g-1). In contrast, liver glycogen values in the fasted group decreased between the 2nd and 4th hour of recovery in response to both feeding regimens. From these results we conclude that fructose is a poor nutritional precursor for rapid glycogen restoration in muscle after exercise, but that both glucose and fructose promote rapid accumulation of glycogen in the liver.

PMID: 3592616 [PubMed - indexed for

Do you know what type of animals were used in this study?

 

[Roush]

so seeing the body as an organism that utilizes nutrients over the long haul (cause maybe that was how it is designed to survive) and not just in certain "time windows" -- it would not be necessary to time insulin injections around a workout .. example : pin homalog post workout and then consume 55 grams of carbs . if nutrient uptake is the goal, it would not matter if it was done post workout ,, or 6 hours later ?

 

[3J]

For a long standing time there have been debates about how quickly you should try and restore your glycogen stores post workout.. I personally follow the old school approach.. But that doesn't mean it makes a significant difference between the two because I myself have followed the new school approach and didn't personally see otherwise.. Unless you plan on multiple sessions of activity a day or are using something like insulin

 

[catalyst]

For a long standing time there have been debates about how quickly you should try and restore your glycogen stores post workout.. I personally follow the old school approach.. But that doesn't mean it makes a significant difference between the two because I myself have followed the new school approach and didn't personally see otherwise.. Unless you plan on multiple sessions of activity a day or are using something like insulin

I train multiple times per day, and can tell the difference when I alter my carb-sources post workout. Yes, this is n=1, blah, blah, but in my case, it is the one that matters most.



Fruits high in fructose, like dark berries (which I enjoy very much) seem to leave me dragging ass a bit during my second workout. And at my age, well, I only have so many decent workouts left.

 

[cybrsage]

They way I look at it, if there IS a window, I want to be in it. If there is not, the being in the "window" is just as effective as not being in it. So, to me, being in that 1 hour window is a safe way to do it either way.

That and I literally live 3 minutes form the gym, by car...so it is VERY easy for me to hit that window.