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Sixpack
09-16-2004, 03:46 PM
Good read
Sixpack

Carbohydrate nutrition before, during, and after exercise.

Costill DL.

The role of dietary carbohydrates (CHO) in the resynthesis of muscle and liver glycogen after prolonged, exhaustive exercise has been clearly demonstrated. The mechanisms responsible for optimal glycogen storage are linked to the activation of glycogen synthetase by depletion of glycogen and the subsequent intake of CHO. Although diets rich in CHO may increase the muscle glycogen stores and enhance endurance exercise performance when consumed in the days before the activity, they also increase the rate of CHO oxidation and the use of muscle glycogen. When consumed in the last hour before exercise, the insulin stimulated-uptake of glucose from blood often results in hypoglycemia, greater dependence on muscle glycogen, and an earlier onset of exhaustion than when no CHO is fed. Ingesting CHO during exercise appears to be of minimal value to performance except in events lasting 2 h or longer. The form of CHO (i.e., glucose, fructose, sucrose) ingested may produce different blood glucose and insulin responses, but the rate of muscle glycogen resynthesis is about the same regardless of the structure.


Amino acids stimulate translation initiation and protein synthesis through an Akt-independent pathway in human skeletal muscle.

Liu Z, Jahn LA, Wei L, Long W, Barrett EJ.

Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA. zl3e@virginia.edu

Studies in vitro as well as in vivo in rodents have suggested that amino acids (AA) not only serve as substrates for protein synthesis, but also as nutrient signals to enhance mRNA translation and protein synthesis in skeletal muscle. However, the physiological relevance of these findings to normal humans is uncertain. To examine whether AA regulate the protein synthetic apparatus in human skeletal muscle, we infused an AA mixture (10% Travesol) systemically into 10 young healthy male volunteers for 6 h. Forearm muscle protein synthesis and degradation (phenylalanine tracer method) and the phosphorylation of protein kinase B (or Akt), eukaryotic initiation factor 4E-binding protein 1, and ribosomal protein S6 kinase (p70(S6K)) in vastus lateralis muscle were measured before and after AA infusion. We also examined whether AA affect urinary nitrogen excretion and whole body protein turnover. Postabsorptively all subjects had negative forearm phenylalanine balances. AA infusion significantly improved the net phenylalanine balance at both 3 h (P < 0.002) and 6 h (P < 0.02). This improvement in phenylalanine balance was solely from increased protein synthesis (P = 0.02 at 3 h and P < 0.003 at 6 h), as protein degradation was not changed. AA also significantly decreased whole body phenylalanine flux (P < 0.004). AA did not activate Akt phosphorylation at Ser(473), but significantly increased the phosphorylation of both eukaryotic initiation factor 4E-binding protein 1 (P < 0.04) and p70(S6K) (P < 0.001). We conclude that AA act directly as nutrient signals to stimulate protein synthesis through Akt-independent activation of the protein synthetic apparatus in human skeletal muscle.




Physiological hyperinsulinemia stimulates p70(S6k) phosphorylation in human skeletal muscle.

Hillier T, Long W, Jahn L, Wei L, Barrett EJ.

Department of Internal Medicine, Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.

Using tracer methods, insulin stimulates muscle protein synthesis in vitro, an effect not seen in vivo with physiological insulin concentrations in adult animals or humans. To examine the action of physiological hyperinsulinemia on protein synthesis using a tracer-independent method in vivo and identify possible explanations for this discrepancy, we measured the phosphorylation of ribosomal protein S6 kinase (P70(S6k)) and eIF4E-binding protein (eIF4E-BP1), two key proteins that regulate messenger ribonucleic acid translation and protein synthesis. Postabsorptive healthy adults received either a 2-h insulin infusion (1 mU/min.kg; euglycemic insulin clamp; n = 6) or a 2-h saline infusion (n = 5). Vastus lateralis muscle was biopsied at baseline and at the end of the infusion period. Phosphorylation of P70(S6k) and eIF4E-BP1 was quantified on Western blots after SDS-PAGE. Physiological increments in plasma insulin (42 +/- 13 to 366 +/- 36 pmol/L; P: = 0.0002) significantly increased p70(S6k) (P: < 0.01), but did not affect eIF4E-BP1 phosphorylation in muscle. Plasma insulin declined slightly during saline infusion (P: = 0.04), and there was no change in the phosphorylation of either p70(S6k) or eIF4E-BP1. These findings indicate an important role of physiological hyperinsulinemia in the regulation of p70(S6k) in human muscle. This finding is consistent with a potential role for insulin in regulating the synthesis of that subset of proteins involved in ribosomal function. The failure to enhance the phosphorylation of eIF4E-BP1 may in part explain the lack of a stimulatory effect of physiological hyperinsulinemia on bulk protein synthesis in skeletal muscle in vivo.

JnJ23
09-16-2004, 04:02 PM
yep good read, thnx

mondesi02
09-16-2004, 04:26 PM
..Is more for endurance performace - like running/sports?

Bignbuff
09-16-2004, 04:28 PM
Very nice.

Where did you find it?

xxghostxx
09-16-2004, 11:34 PM
Costill is such an amazing researcher/author/phd, the physiology of sport and exercise that he and wilmore are responsible for was one of the best texts I've ever read. Like BigNBuff asked, where'd you find this at?

Sixpack
09-17-2004, 03:28 AM
On another website posted by "Bobo" he is a nutrition guru and mod on another site. I have been talking with him for awhile. Prob the most knowledgeable bro I have met in awhile and he is only 20, u should see this guy

mondesi02
09-17-2004, 03:51 AM
On another website posted by "Bobo" he is a nutrition guru and mod on another site. I have been talking with him for awhile. Prob the most knowledgeable bro I have met in awhile and he is only 20, u should see this guy

..ya I have read alot of his posts..I had no clue he is only 20 - I would have to agree, probably one of the brightest minds in the fields of nutrtion out there.

Sixpack
09-17-2004, 04:00 AM
Ya he has a PT buisness actually I think he is 19 lol, Mondesi damn bro u up already lol, I am off to do cardio brother, another thing the new Sesathin gel caps are in stock got my order in to test them out

mondesi02
09-17-2004, 04:08 AM
Ya he has a PT buisness actually I think he is 19 lol, Mondesi damn bro u up already lol, I am off to do cardio brother, another thing the new Sesathin gel caps are in stock got my order in to test them out

..damn 19? - Most of his threads/articles are on the money i think!

Ya bro, I have been up since 3:00am! I had a phone conversation with my b-partner in taiwan at 3:30am - it liked 7pm over there right now..I'm thrilled right now...Sesathin gel caps are out- Man thats the best news I have heard all week. Now I can take the caps when I go out to dinner instead of sneeking the bottle in my pocket! yee-haw!

Thanks bro!

xil
09-17-2004, 05:02 AM
He's 31 I believe... and yes, the guy is great