Bobo's gonna hate me for this but, after reading and debating the Hi vs Low GI post WO drink I decided to do some investigation of my own and I'm now more confused than ever. After reading the two studies produced by Bobo in another thread they where "The effects of simple-carbohydrate (CHO)- and complex-CHO-rich diets on skeletal muscle glycogen content were compared" and "The effect of free glutamine and peptide ingestion on the rate of muscle glycogen resynthesis in man.". However after closer investigation I realize these may have been misinterrepted.
First, in the study of complex vs simple CHO, this study was conducted over a 3 day time where no resistance training was involved and glycogen depletion was only achieved from a previous 3 day low carb diet. Now this may speak in terms of types of CHO to use in ones regular diet but I don't think this is a good claim to a low GI post workout drink.
Second, in the study of glycogen resysnthesis, it was claimed that resysnthesis was the same in the whey/wheat group as the glucose/glutamine group, but what I think may have been overlooked was that they ALL consumed the same amount of glucose with their respective drinks and now GI level is given. To me this only proves that the addition of protein to a post workout shake has no effect on glycogen resysnthesis.
Now I decide to grab a few studies that do show a difference in a low vs high GI post workout drink, these are:
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Sports Med 1997 Mar;23(3):164-72 Related Articles, Links
Glycaemic index and optimal performance.
Walton P, Rhodes EC.
School of Human Kinetics, University of British Columbia, Vancouver, Canada.
It is widely documented that athletes should consume carbohydrates prior to, during and after exercise. Ingestion of carbohydrates at these times will optimise performance and recovery. In spite of this knowledge, there is a paucity of information available to athletes concerning the types of carbohydrate foods to select. Therefore, it is suggested that the glycaemic index may be an important resource when selecting an ideal carbohydrate. The glycaemic index categories foods containing carbohydrates according to the blood glucose response that they elicit. Carbohydrate foods evoking the greatest responses are considered to be high glycaemic index foods, while those producing a relatively smaller response are categorised as low glycaemic index foods. Athletes wishing to consume carbohydrates 30 to 60 minutes before exercise should be encouraged to ingest low glycaemic index foods. Consuming these types of foods will decrease the likelihood of creating hyperglycaemia and hyperinsulinaemia at the onset of exercise, while providing exogenous carbohydrate throughout exercise. It is recommended that high glycaemic index foods be consumed during exercise. These foods will ensure rapid digestion and absorption, which will lead to elevated blood glucose levels during exercise. Post-exercise meals should consist of high glycaemic index carbohydrates. Low glycaemic foods do not induce adequate muscle glycogen resynthesis compared with high glycaemic index foods.
----------------------------------------------------------------------
Int J Sports Med 1996 Jul;17(5):373-8 Related Articles, Links
The influence of starch structure on glycogen resynthesis and subsequent cycling performance.
Jozsi AC, Trappe TA, Starling RD, Goodpaster B, Trappe SW, Fink WJ, Costill DL.
Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.
The present study was designed to evaluate the influence of starch structure on muscle glycogen resynthesis and cycling performance. Eight male cyclists (22 +/- 1 yr) completed an exercise protocol (DP) to decrease vastus lateralis glycogen concentration. This exercise consisted of 60 min cycling at 75% VO2max, followed by six 1-min sprints at approximately 125% VO2max with 1 min rest intervals. In the 12 hr after the exercise each subject consumed approximately 3000 kcal (65:20:15% carbohydrate, fat and protein). All of the carbohydrate (CHO) consumed was derived from one of four solutions; 1) glucose, 2) maltodextrin (glucose polymer), 3) waxy starch (100% amylopectin), or 4) resistant starch (100% amylose). Muscle biopsies were taken from the vastus lateralis muscle after DP and 24 hr later to determine glycogen concentrations. A 30 min cycling time trial (TT) was performed following the 24 hr post-DP muscle biopsy to examine the influence of the feeding regimen on total work output. The post-DP glycogen concentrations were similar among the four trials, ranging from 220.3 +/- 29.2 to 264 +/- 48.3 mmol.kg-1 dry weight (d.w.) muscle. Twenty-four hours after DP, muscle glycogen concentration had increased less (p < 0.05) in the resistant starch trial (+90.8 +/- 12.8 mmol.kg-1 d.w.) than in the glucose (+197.7 +/- 31.6 mmol.kg-1 d.w.), maltodextrin (+136.7 +/- 24.5 mmol.kg-1 d.w.) and waxy starch (+171.8 +/- 37.1 mmol.kg-1 d.w.) trials. There were no differences in total work output during the TT, or blood lactate concentration immediately following the TT in any of the CHO trials. In summary, glycogen resynthesis was attenuated following ingestion of starch with a high amylose content, relative to amylopectin or glucose; however, short duration time trial performance was unaffected.
---------------------------------------------------------------------
Aust J Sci Med Sport 1997 Mar;29(1):3-10 Related Articles, Links
Nutrition for post-exercise recovery.
Burke LM.
Australian Institute of Sport, ACT, Australia.
Recovery after exercise poses an important challenge to the modern athlete. Important issues include restoration of liver and muscle glycogen stores, and the replacement of fluid and electrolytes lost in sweat. Rapid resynthesis of muscle glycogen stores is aided by the immediate intake of carbohydrate (I g.kg-1 BM each 2 hours), particularly of high glycemic index carbohydrate foods, leading to a total intake over 24 hours of 7-10 g.kg-1 BM. Provided adequate carbohydrate is consumed it appears that the frequency of intake, the form (liquid versus solid) and the presence of other macronutrients does not affect the rate of glycogen storage. Practical considerations, such as the availability and appetite appeal of foods or drinks, and gastrointestinal comfort may determine ideal carbohydrate choices and intake patterns. Rehydration requires a special fluid intake plan since thirst and voluntary intake will not provide for full restoration of sweat losses in the acute phase (0-6 hr) of recovery. Steps should be taken to ensure that a supply of palatable drinks is available after exercise. Sweetened drinks are generally preferred and can contribute towards achieving carbohydrate intake goals. Replacement of sodium lost in sweat is important in maximising the retention of ingested fluids. A sodium content of 50-90 mmol.L-1 may be necessary for optimal rehydration; however commercial sports drinks are formulated with a more moderate sodium content (10-25 mmol.L-1). It may be necessary to consume 150% of fluid losses to allow for complete fluid restoration. Caffeine and alcohol containing beverages are not ideal rehydration fluids since they promote an increased rate of diuresis.
----------------------------------------------------------------------
Int J Sports Med 1998 Jun;19 Suppl 2:S142-5 Related Articles, Links
Glycogen resynthesis after exercise: effect of carbohydrate intake.
Ivy JL.
Department of Kinesiology, University of Texas, Austin 78712, USA. [email protected]
To maximize glycogen resynthesis after exercise, a carbohydrate supplement in excess of 1.0 g x kg(-1) body wt should be consumed immediately after competition or a training bout. Continuation of supplementation every two hours will maintain a rapid rate of storage up to six hours post exercise. Supplements composed of glucose or glucose polymers are the most effective for replenishment of muscle glycogen, whereas fructose is most beneficial for the replenishment of liver glycogen. The addition of protein to a carbohydrate supplement may also increase the rate of glycogen storage due to the ability of protein and carbohydrate to act synergistically on insulin secretion.
PMID: 9694422 [PubMed - indexed for MEDLINE]
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Now there are quite a few others but I'll stop there for now. Now I'm not arguing that a diet that consist of mainly low GI foods is not benificial in reduce overall fat storage but I can't say I'm in away convinced that a low GI post workout drink is as effective as a high GI one.
Sorry to bring this up again but I just want to make sure I'm getting the most out of my post WO drink and I'm not sure that low GI is the way to go. Please, let me know if I'm missing something here.
First, in the study of complex vs simple CHO, this study was conducted over a 3 day time where no resistance training was involved and glycogen depletion was only achieved from a previous 3 day low carb diet. Now this may speak in terms of types of CHO to use in ones regular diet but I don't think this is a good claim to a low GI post workout drink.
Second, in the study of glycogen resysnthesis, it was claimed that resysnthesis was the same in the whey/wheat group as the glucose/glutamine group, but what I think may have been overlooked was that they ALL consumed the same amount of glucose with their respective drinks and now GI level is given. To me this only proves that the addition of protein to a post workout shake has no effect on glycogen resysnthesis.
Now I decide to grab a few studies that do show a difference in a low vs high GI post workout drink, these are:
---------------------------------------------------------------------
Sports Med 1997 Mar;23(3):164-72 Related Articles, Links
Glycaemic index and optimal performance.
Walton P, Rhodes EC.
School of Human Kinetics, University of British Columbia, Vancouver, Canada.
It is widely documented that athletes should consume carbohydrates prior to, during and after exercise. Ingestion of carbohydrates at these times will optimise performance and recovery. In spite of this knowledge, there is a paucity of information available to athletes concerning the types of carbohydrate foods to select. Therefore, it is suggested that the glycaemic index may be an important resource when selecting an ideal carbohydrate. The glycaemic index categories foods containing carbohydrates according to the blood glucose response that they elicit. Carbohydrate foods evoking the greatest responses are considered to be high glycaemic index foods, while those producing a relatively smaller response are categorised as low glycaemic index foods. Athletes wishing to consume carbohydrates 30 to 60 minutes before exercise should be encouraged to ingest low glycaemic index foods. Consuming these types of foods will decrease the likelihood of creating hyperglycaemia and hyperinsulinaemia at the onset of exercise, while providing exogenous carbohydrate throughout exercise. It is recommended that high glycaemic index foods be consumed during exercise. These foods will ensure rapid digestion and absorption, which will lead to elevated blood glucose levels during exercise. Post-exercise meals should consist of high glycaemic index carbohydrates. Low glycaemic foods do not induce adequate muscle glycogen resynthesis compared with high glycaemic index foods.
----------------------------------------------------------------------
Int J Sports Med 1996 Jul;17(5):373-8 Related Articles, Links
The influence of starch structure on glycogen resynthesis and subsequent cycling performance.
Jozsi AC, Trappe TA, Starling RD, Goodpaster B, Trappe SW, Fink WJ, Costill DL.
Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.
The present study was designed to evaluate the influence of starch structure on muscle glycogen resynthesis and cycling performance. Eight male cyclists (22 +/- 1 yr) completed an exercise protocol (DP) to decrease vastus lateralis glycogen concentration. This exercise consisted of 60 min cycling at 75% VO2max, followed by six 1-min sprints at approximately 125% VO2max with 1 min rest intervals. In the 12 hr after the exercise each subject consumed approximately 3000 kcal (65:20:15% carbohydrate, fat and protein). All of the carbohydrate (CHO) consumed was derived from one of four solutions; 1) glucose, 2) maltodextrin (glucose polymer), 3) waxy starch (100% amylopectin), or 4) resistant starch (100% amylose). Muscle biopsies were taken from the vastus lateralis muscle after DP and 24 hr later to determine glycogen concentrations. A 30 min cycling time trial (TT) was performed following the 24 hr post-DP muscle biopsy to examine the influence of the feeding regimen on total work output. The post-DP glycogen concentrations were similar among the four trials, ranging from 220.3 +/- 29.2 to 264 +/- 48.3 mmol.kg-1 dry weight (d.w.) muscle. Twenty-four hours after DP, muscle glycogen concentration had increased less (p < 0.05) in the resistant starch trial (+90.8 +/- 12.8 mmol.kg-1 d.w.) than in the glucose (+197.7 +/- 31.6 mmol.kg-1 d.w.), maltodextrin (+136.7 +/- 24.5 mmol.kg-1 d.w.) and waxy starch (+171.8 +/- 37.1 mmol.kg-1 d.w.) trials. There were no differences in total work output during the TT, or blood lactate concentration immediately following the TT in any of the CHO trials. In summary, glycogen resynthesis was attenuated following ingestion of starch with a high amylose content, relative to amylopectin or glucose; however, short duration time trial performance was unaffected.
---------------------------------------------------------------------
Aust J Sci Med Sport 1997 Mar;29(1):3-10 Related Articles, Links
Nutrition for post-exercise recovery.
Burke LM.
Australian Institute of Sport, ACT, Australia.
Recovery after exercise poses an important challenge to the modern athlete. Important issues include restoration of liver and muscle glycogen stores, and the replacement of fluid and electrolytes lost in sweat. Rapid resynthesis of muscle glycogen stores is aided by the immediate intake of carbohydrate (I g.kg-1 BM each 2 hours), particularly of high glycemic index carbohydrate foods, leading to a total intake over 24 hours of 7-10 g.kg-1 BM. Provided adequate carbohydrate is consumed it appears that the frequency of intake, the form (liquid versus solid) and the presence of other macronutrients does not affect the rate of glycogen storage. Practical considerations, such as the availability and appetite appeal of foods or drinks, and gastrointestinal comfort may determine ideal carbohydrate choices and intake patterns. Rehydration requires a special fluid intake plan since thirst and voluntary intake will not provide for full restoration of sweat losses in the acute phase (0-6 hr) of recovery. Steps should be taken to ensure that a supply of palatable drinks is available after exercise. Sweetened drinks are generally preferred and can contribute towards achieving carbohydrate intake goals. Replacement of sodium lost in sweat is important in maximising the retention of ingested fluids. A sodium content of 50-90 mmol.L-1 may be necessary for optimal rehydration; however commercial sports drinks are formulated with a more moderate sodium content (10-25 mmol.L-1). It may be necessary to consume 150% of fluid losses to allow for complete fluid restoration. Caffeine and alcohol containing beverages are not ideal rehydration fluids since they promote an increased rate of diuresis.
----------------------------------------------------------------------
Int J Sports Med 1998 Jun;19 Suppl 2:S142-5 Related Articles, Links
Glycogen resynthesis after exercise: effect of carbohydrate intake.
Ivy JL.
Department of Kinesiology, University of Texas, Austin 78712, USA. [email protected]
To maximize glycogen resynthesis after exercise, a carbohydrate supplement in excess of 1.0 g x kg(-1) body wt should be consumed immediately after competition or a training bout. Continuation of supplementation every two hours will maintain a rapid rate of storage up to six hours post exercise. Supplements composed of glucose or glucose polymers are the most effective for replenishment of muscle glycogen, whereas fructose is most beneficial for the replenishment of liver glycogen. The addition of protein to a carbohydrate supplement may also increase the rate of glycogen storage due to the ability of protein and carbohydrate to act synergistically on insulin secretion.
PMID: 9694422 [PubMed - indexed for MEDLINE]
----------------------------------------------------------------------
Now there are quite a few others but I'll stop there for now. Now I'm not arguing that a diet that consist of mainly low GI foods is not benificial in reduce overall fat storage but I can't say I'm in away convinced that a low GI post workout drink is as effective as a high GI one.
Sorry to bring this up again but I just want to make sure I'm getting the most out of my post WO drink and I'm not sure that low GI is the way to go. Please, let me know if I'm missing something here.