OPTIMIZING POST-EXERCISE MUSCLE GLYCOGEN SYNTHESIS: CARBOHYDRATE AND AMINO ACID/PROTEIN FEEDINGS

Abstract

298 This study aimed at investigating whether addition of a protein/amino acid mixture to a carbohydrate containing solution can accelerate glycogen synthesis. Eight highly trained cyclists (age 24±0.6 yr, BMI 21.4±0.6 kg·m−2, Wmax 390±8 W) visited the laboratory, after an overnight fast, on 3 occasions in which a control and 2 other beverage compositions were tested. After performing a vigorous glycogen depletion protocol on a cycle ergometer a muscle biopsy was taken from the M. vastus lateralis. Subjects received a beverage volume of 3.5 ml·kg−1 bw every half hour to ensure ingestion of 0.8 g·kg−1hr−1 carbohydrate (CHO), 0.8 g·kg−1 hr−1 carbohydrate+0.4 g·kg−1hr−1 of a mixture of wheat protein+Leu and Phe (in pilot studies proven to be highly insulinotropic) (CHO+PRO) or an equicaloric amount of 1.2 g·kg−1hr−1 carbohydrates (CHO+CHO). After 5 hours a 2nd biopsy was taken. Plasma insulin responses (area under curve) were different in all trials with highest values in the CHO+PRO trial and lowest in the CHO trial (15.9±2.2, 12.3±1.8 and 8.6±0.9 mU 5hrs ml−1:P<0.05). Net muscle glycogen storage was increased in both trials compared to the control trial (*: P<0.05). In conclusion carbohydrate intake should be well above the previously suggested 0.8 g·kg−1hr−1 to achieve optimal glycogen synthesis rates. Secondly, addition of this insulinotropic protein/amino acid mixture to a carbohydrate solution (at an intake of 0.8 g carbohydrate·kg−1hr−1) accelerates glycogen synthesis.(Figure)Figure