Do post-exercise carbs actually help?

[NO HYPE]

It seems as though post-exercise protein combined with carbohydrates does nothing to enhance protein synthesis. However when combined with leucine, there is a significant difference.




Am J Physiol Endocrinol Metab. 2007 Jul 3
Co-ingestion of carbohydrate with protein does not further augment post-exercise muscle protein synthesis.

The present study was designed to assess the impact of co-ingestion of various amounts of carbohydrate combined to an ample amount of protein intake on post-exercise muscle protein synthesis rates. Ten healthy, fit men (20+/-0.3 y) were randomly assigned to 3 cross-over experiments. After 60 min of resistance exercise, subjects consumed 0.3 g.kg(-1).h(-1) protein hydrolysate with 0, 0.15, or 0.6 g.kg(-1).h(-1) carbohydrate during a 6 h recovery period (PRO, PRO+LCHO, and PRO+HCHO, respectively). Primed, continuous infusions with L-[ring-(13)C6]phenylalanine, L-[ring-(2)H2]tyrosine, and [6,6-(2)H2]glucose were applied, and blood and muscle samples were collected to assess whole-body protein turnover and glucose kinetics as well as protein fractional synthesis rate (FSR) in the vastus lateralis muscle over 6 h of post-exercise recovery. Plasma insulin responses were significantly greater in PRO+HCHO compared to PRO+LCHO and PRO (18.4+/-2.9 vs. 3.7+/-0.5 and 1.5+/-0.2 U.6h.L(-1), respectively: P<0.001). Plasma glucose rate of appearance (Ra) and disappearance (Rd) increased over time in PRO+HCHO and PRO+LCHO but not in PRO. Plasma glucose Ra and Rd were substantially greater in PRO+HCHO vs both PRO and PRO+LCHO (P<0.01). Whole-body protein breakdown, synthesis and oxidation rates, as well as whole-body protein balance did not differ between experiments. Mixed muscle FSR did not differ between treatments and averaged 0.10+/-0.01, 0.10+/-0.01 and 0.11+/-0.01 %.h(-1) in the PRO, PRO+LCHO and PRO+HCHO experiments, respectively. In conclusion, co-ingestion of carbohydrate during recovery does not further stimulate post-exercise muscle protein synthesis when ample protein is ingested. http://www.ncbi.nlm.nih.gov/sites/en...ubmed_RVDocSum



Am J Physiol Endocrinol Metab 288: E645-E653, 2005.
Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects

The present study was designed to determine postexercise muscle protein synthesis and whole body protein balance following the combined ingestion of carbohydrate with or without protein and/or free leucine. Eight male subjects were randomly assigned to three trials in which they consumed drinks containing either carbohydrate (CHO), carbohydrate and protein (CHO+PRO), or carbohydrate, protein, and free leucine (CHO+PRO+Leu) following 45 min of resistance exercise. A primed, continuous infusion of L-[ring-13C6]phenylalanine was applied, with blood samples and muscle biopsies collected to assess fractional synthetic rate (FSR) in the vastus lateralis muscle as well as whole body protein turnover during 6 h of postexercise recovery. Plasma insulin response was higher in the CHO+PRO+Leu compared with the CHO and CHO+PRO trials (+240 ? 19% and +77 ? 11%, respectively, P < 0.05). Whole body protein breakdown rates were lower, and whole body protein synthesis rates were higher, in the CHO+PRO and CHO+PRO+Leu trials compared with the CHO trial (P < 0.05). Addition of leucine in the CHO+PRO+Leu trial resulted in a lower protein oxidation rate compared with the CHO+PRO trial. Protein balance was negative during recovery in the CHO trial but positive in the CHO+PRO and CHO+PRO+Leu trials. In the CHO+PRO+Leu trial, whole body net protein balance was significantly greater compared with values observed in the CHO+PRO and CHO trials (P < 0.05). Mixed muscle FSR, measured over a 6-h period of postexercise recovery, was significantly greater in the CHO+PRO+Leu trial compared with the CHO trial (0.095 ? 0.006 vs. 0.061 ? 0.008%/h, respectively, P < 0.05), with intermediate values observed in the CHO+PRO trial (0.0820 ? 0.0104%/h). We conclude that coingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance compared with the intake of carbohydrate only.

In conclusion, the combined ingestion of protein and leucine with carbohydrate improves whole body protein balance during recovery from resistance exercise compared with the ingestion of carbohydrate or carbohydrate with protein. The combined ingestion of both leucine and protein with carbohydrate augments postexercise mixed muscle protein synthesis compared with the ingestion of only carbohydrate. The present data indicate that the additional ingestion of free leucine in combination with protein and carbohydrate likely represents an effective strategy to increase muscle anabolism following resistance exercise. http://ajpendo.physiology.org/cgi/co.../4/E645?ck=nck

[dance2trance]

Names to look out for on this topic are Hawley JA, Tipton KD and Van Loon LJ. (Hawley and Tipton are colleagues of a colleague of mine)

Yeah those studies are in-line with the current paradigm, that leucine and insulin together allow protein synthesis in skeletial muscle.

SEARCH QUERY: phosphotidylinositol-3-kinase (insulin signalling pathway)

[jfla32033]

You need calories for your muscles.

Simple carbs have calories, last time I checked. And they are fast acting so they get digested quicker...this I'm sure you know.

Don't overlook the basics.

[lionelxxl]

NO HYPE, dance2trance, what do you make of this. Potential for further research?

Personally, i feel that taking carbs PWO is much 'safer' as where it'll be better utilized during the post workout window. Rather than bolusing it in some other meal where i know it'll not be utilized in hours preceding or after it.

I see the studies and i tell myself, "ok, carbs don't seem to aid in protein sysnthesis PWO. But it doesn't inhibit it either. I'd rather have em there then at any other time as i know it'll go to good use (glycogen stores) .. again, taking note not to consume TOO MUCH carbs."

[dance2trance]

I see the studies and i tell myself, "ok, carbs don't seem to aid in protein sysnthesis PWO. But it doesn't inhibit it either. I'd rather have em there then at any other time as i know it'll go to good use (glycogen stores) .. again, taking note not to consume TOO MUCH carbs."

As depicted in the flow chart i attached of insulin signalling, insulin sensitivity of the cell leads to mTOR activation, a gene whose activation has been linked to muscle protein synthesis.

Simple carbs post-workout WILL raise insulin levels. However the studies above suggest that this has little effect on muscle protein synthesis, and POSSIBLY suggesting that insulin sensitivity DECREASES after exercise, which is totally inconsistant with the plethora of studies which show exercise INCREASES insulin sensitivity.

The questions that need to be answered:

-If raised insulin levels have little effect on muscle protein synthesis, could this due to decreased insulin sensitivity? (probably not, analysis of Insulin receptor, IRS1 + 2, Akt phosphorylation and mTOR activation post-workout would help to refute this possible theory)

-It is widely accepted that exercise induces insulin sensitivity. And that exercise induces a transient burst of ROS. BUT do ROS improve or decrease insulin sensitivity? ----> this is my study, my model is black mice, sample size of at least 40 depending on time...we are using GPX -/- and wild type mice...and sensitivity will be measured on glucose and insulin tolerance tests and blood-glucose levels post-exercise over a surveilance period of 2 hours after a glucose or insulin shot.

[Dr.Dave1]

I agree that the insulin pathway is key, but there are other pathways which are also affected by exercise. Growth hormone levels have been shown to increase post exercise as have testosterone levels (less dramatically). I think insulin signaling is part of the big picture but not the end all be all. It is more of an interaction of all the systems working together or against each other as growth hormone can cause insulin resistance . . .

[Skigazzi]

SO....If I continue to do this:

Immediately post WO - WMS and BCAAs

20-30 Minutes Later - WPI + Leucine

I have my bases covered? yes - no?

(Good posts from all here.)

[powerman2000]

Wouldn't the absence of carbs pwo cause the protein ingested to be used to restore glycogen instead of building and repairing muscle tissues? I always thought that was the whole point of eating simple carbs pwo to restore glycogen levels right away so as not to have the protein broken down for glycogen restoral.

[Elliptical Envy]

Wouldn't the absence of carbs pwo cause the protein ingested to be used to restore glycogen instead of building and repairing muscle tissues? I always thought that was the whole point of eating simple carbs pwo to restore glycogen levels right away so as not to have the protein broken down for glycogen restoral.

I don't believe in the post-workout simple carb shake at all, because the whole point in post-workout nutrition would be protein synthesis. You won't exhaust all your glycogen stores during a workout unless you are working out for 2+ hours or are an endurance athelete. You could get away with a low-GI carb post-workout since the aminos would be the key to halting catabolism and protein synthesis. I am not sure how protein could be used for glycogen since it isn't broken down into glucose unless you are talking about gluconeogenisis, but that would mean that you are in a starved state and glucagon is taking over.

[Elliptical Envy]

You need calories for your muscles.

Simple carbs have calories, last time I checked. And they are fast acting so they get digested quicker...this I'm sure you know.

Don't overlook the basics.

I'm sorry but this state is just ignorant. Protein, carbs, and fats all have calories. The whole point to post-workout nutrition is protein synthesis. Why is it that you want to take a simple carb to replenish muscle glycogen? It seems like you are so concerned with speed, but if you have a proper pre-workout meal that won't be a factor.

[powerman2000]

I don't believe in the post-workout simple carb shake at all, because the whole point in post-workout nutrition would be protein synthesis. You won't exhaust all your glycogen stores during a workout unless you are working out for 2+ hours or are an endurance athelete. You could get away with a low-GI carb post-workout since the aminos would be the key to halting catabolism and protein synthesis. I am not sure how protein could be used for glycogen since it isn't broken down into glucose unless you are talking about gluconeogenisis, but that would mean that you are in a starved state and glucagon is taking over.

So are you saying that as long as some glycogen is left in our muscle tissues that none of the protein or aminos consumed pwo would be broken down into glucose to help replenish glycogen stores?

You don't have to be in a starved state for gluconeogenesis to occur. If I was eating 4,000 cals of meat protein everyday I wouldn't be starving but I would definitely be converting some of that protein into glucose.

Isn't that right?

[HalleluYAH]

Wouldn't the absence of carbs pwo cause the protein ingested to be used to restore glycogen instead of building and repairing muscle tissues? I always thought that was the whole point of eating simple carbs pwo to restore glycogen levels right away so as not to have the protein broken down for glycogen restoral.

Exactly^^^.

Provided ample PRO is taken postWO, the only reason to take CHO postWO is muscle glycogen replenishment.

[Elliptical Envy]

So are you saying that as long as some glycogen is left in our muscle tissues that none of the protein or aminos consumed pwo would be broken down into glucose to help replenish glycogen stores?

You don't have to be in a starved state for gluconeogenesis to occur. If I was eating 4,000 cals of meat protein everyday I wouldn't be starving but I would definitely be converting some of that protein into glucose.

Isn't that right?

The body will not convert protein to glucose as long as you have glycogen present. The body would use protein for other more important purposes like protein synthesis and muscle repair. The average bodybuilder that eats properly doesn't have to worry about muscle being broken down via gluconeogenesis (finally spelled it right) because insulin would be present. Insulin and glucagon can't exist together so whenever one is up the other is down. If you don't eat protein the body will break down muscle to amino acids to perform tasks via gluconeogenesis.

What I am saying is that so many people are concerned about their carb source post-workout you would think the whole motive behind post-workout would be glycogen replenishment and it isn't. The GI of the carb doesn't matter in the post-workout scenerio especially if you have proper pre-workout nutrition. Here is a study about the GI of carbs post-workout. Mind you this study was done on people in a fasted state, but I still think this should apply. I'll find more studies later.

The Metabolic Responses to High Carbohydrate Meals with Different Glycemic Indices Consumed During Recovery from Prolonged Strenuous Exercise

Emma Stevenson; Clyde Williams; Helen Biscoe

Abstract
This study investigated the metabolic responses to high glycemic index (HGI) or low glycemic index (LGI) meals consumed during recovery from prolonged exercise. Eight male, trained athletes undertook 2 trials. Following an overnight fast, subjects completed a 90-min run at 70% VO2max. Meals were provided 30 min and 2 h following cessation of exercise. The plasma glucose responses to both meals were greater in the HGI trial compared to the LGI trial (P < 0.05). Following breakfast, there were no differences in the serum insulin concentrations between the trials; however, following lunch, concentrations were higher in the HGI trial compared to the LGI trial (P < 0.05). This suggests that the glycemic index of the carbohydrates consumed during the immediate post-exercise period might not be important as long as sufficient carbohydrate is consumed. The high insulin concentrations following a HGI meal later in the recovery period could facilitate further muscle glycogen resynthesis.

[powerman2000]

The body will not convert protein to glucose as long as you have glycogen present.

So carbs could be eaten whenever.

What I am saying is that so many people are concerned about their carb source post-workout you would think the whole motive behind post-workout would be glycogen replenishment and it isn't. The GI of the carb doesn't matter in the post-workout scenerio especially if you have proper pre-workout nutrition. Here is a study about the GI of carbs post-workout. Mind you this study was done on people in a fasted state, but I still think this should apply. I'll find more studies later.

I'm not very concerned with the source of carbs, but just that they be eaten soon after a training bout.

[Elliptical Envy]

So carbs could be eaten whenever.

I'm not very concerned with the source of carbs, but just that they be eaten soon after a training bout.

I do believe that people eat carbs post-workout, which is needed, but the misconception is the whole high-GI vs. low-GI thing. I think I did a lot of typing in my last post and probably rambled on a bit....damn these cognitive enhancers.

[powerman2000]

I do believe that people eat carbs post-workout, which is needed, but the misconception is the whole high-GI vs. low-GI thing. I think I did a lot of typing in my last post and probably rambled on a bit....damn these cognitive enhancers.

I'm definitely not hung up on using High GI carbs for pwo nutrition.

So I guess we are in agreement here.

[Elliptical Envy]

I'm definitely not hung up on using High GI carbs for pwo nutrition.

So I guess we are in agreement here.

1 member down 200000000000000000000 members to go.

[redhawk76]

oats for me PWO

[powerman2000]

oats for me PWO

Me too, and sometimes a little Gatorade during the summer months.

[RB12]

I'm definitely not hung up on using High GI carbs for pwo nutrition.

So I guess we are in agreement here.

1 member down 200000000000000000000 members to go.

i'm with you as well, so you can check me off the list

great info here guys, thanks

[Elliptical Envy]

i'm with you as well, so you can check me off the list

great info here guys, thanks

Okay 3 down. I'm not about to count down anymore. I'm strictly low-GI post-workout from now on after reading some posts by BoBo.

[powerman2000]

Okay 3 down. I'm not about to count down anymore. I'm strictly low-GI post-workout from now on after reading some posts by BoBo.

I don't think the GI has to be low either. I just find that lower GI carbs are usually more nutritious.

[Elliptical Envy]

I don't think the GI has to be low either. I just find that lower GI carbs are usually more nutritious.

I don't think the GI has to be high as reported by many broscience articles. Lower GI carbs are pretty damn nutritious and all those sugars have zero micronutrients in them.

[powerman2000]

I don't think the GI has to be high as reported by many broscience articles. Lower GI carbs are pretty damn nutritious and all those sugars have zero micronutrients in them.

You ever eat any Quinoa?

[Elliptical Envy]

You ever eat any Quinoa?

Naw, but I have heard about it. Should I check it out?

[Rodzilla]

SO....If I continue to do this:

Immediately post WO - WMS and BCAAs

20-30 Minutes Later - WPI + Leucine

I have my bases covered? yes - no?

(Good posts from all here.)

I think it would be WMS + BCAA's INCLUDING Leucine, then 15-20 later WPI

[bigla2004]

Just for moral support envy, I too use oats pwo.

[powerman2000]

Naw, but I have heard about it. Should I check it out?

I highly recommend it. I'm eating some with my chicken and green beans right now.

It's pretty cheap, tastes good, easy to prepare and there is no other grain that is more nutritious.

Two thumbs up from me.

[Elliptical Envy]

Just for moral support envy, I too use oats pwo.

I highly recommend it. I'm eating some with my chicken and green beans right now.

It's pretty cheap, tastes good, easy to prepare and there is no other grain that is more nutritious.

Two thumbs up from me.

If it is good enough for powerman then it should be good enough for me. I'll go to the grocery store later and check it out. Thanks for the suggestion.

[powerman2000]

If it is good enough for powerman then it should be good enough for me. I'll go to the grocery store later and check it out. Thanks for the suggestion.

I hope you'll like it.