Zitat:
J Appl Physiol. 2004 Feb;96(2):674-8. Epub 2003 Oct 31.
Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise.
Borsheim E, Cree MG, Tipton KD, Elliott TA, Aarsland A, Wolfe RR.
Department of Surgery, Shriners Hospitals for Children-Galveston, University of Texas Medical Branch, Galveston, Texas 77550, USA.
The purpose of this study was to determine the effect of ingestion of 100 g of carbohydrates on net muscle protein balance (protein synthesis minus protein breakdown) after resistance exercise. Two groups of eight subjects performed a resistance exercise bout (10 sets of 8 repetitions of leg presses at 80% of 1-repetition maximum) before they rested in bed for 4 h. One group (CHO) received a drink consisting of 100 g of carbohydrates 1 h postexercise. The other group (Pla) received a noncaloric placebo drink. Leg amino acid metabolism was determined by infusion of 2H5- or 13C6-labeled phenylalanine, sampling from femoral artery and vein, and muscle biopsies from vastus lateralis. Drink intake did not affect arterial insulin concentration in Pla, whereas insulin increased several times after the drink in CHO (P < 0.05 vs. Pla). Arterial phenylalanine concentration fell slightly after the drink in CHO. Net muscle protein balance between synthesis and breakdown did not change in Pla, whereas it improved in CHO from -17 +/- 3 nmol.ml(-1).100 ml leg(-1) before drink to an average of -4 +/- 4 and 0 +/- 3 nmol.ml(-1).100 ml leg(-1) during the second and third hour after the drink, respectively (P < 0.05 vs. Pla during last hour). The improved net balance in CHO was due primarily to a progressive decrease in muscle protein breakdown. We conclude that ingestion of carbohydrates improved net leg protein balance after resistance exercise. However, the effect was minor and delayed compared with the previously reported effect of ingestion of amino acids.
Fulltext:
Zitat:
This study is the first to compare net muscle protein balance (protein synthesis minus breakdown) after carbohydrate ingestion with control after exercise. The principal finding was that intake of 100 g of carbohydrates after resistance exercise improved muscle net protein balance. However, this improvement was of questionable physiological significance because the net balance did not reach positive values and the improvement was minor compared with the reported effect of intake of amino acids.
Und sie stellen die Hypothese auf, dass es eventuell günstig wäre, das Protein etwas zeitversetzt zu den Carbs zu trinken:
Zitat:
The apparently delayed action of insulin on net muscle protein anabolism, as opposed to the rapid effect of amino acids, suggests that delayed intake of amino acids relative to carbohydrates could amplify the potential interactive effect. With this approach, amino acids would be taken up at the peak of insulin action on muscle. With such a staggered approach, a physiologically significant effect of carbohydrate intake after exercise might be evident. However, when given alone or at the same time as free EAA, carbohydrates seem to have little effect on net muscle protein synthesis.
