title: Addition of glutamine to essential amino acids and carbohydrate does not enhance anabolism in young human males following exercise.
abstract: We examined the effect of a post-exercise oral carbohydrate (CHO, 1 g.kg(-1).h(-1)) and essential amino acid (EAA, 9.25 g) solution containing glutamine (0.3 g/kg BW; GLN trial) versus an isoenergetic CHO-EAA solution without glutamine (control, CON trial) on muscle glycogen resynthesis and whole-body protein turnover following 90 min of cycling at 65% VO2 peak. Over the course of 3 h of recovery, muscle biopsies were taken to measure glycogen resynthesis and mixed muscle protein synthesis (MPS), by incorporation of [ring-2H5] phenylalanine. Infusion of [1-13C] leucine was used to measure whole-body protein turnover. Exercise resulted in a significant decrease in muscle glycogen (p < 0.05) with similar declines in each trial. Glycogen resynthesis following 3 h of recovery indicated no difference in total accumulation or rate of repletion. Leucine oxidation increased 2.5 fold (p < 0.05) during exercise, returned to resting levels immediately post-exercise,and was again elevated at 3 h post-exercise (p < 0.05). Leucine flux, an index of whole-body protein breakdown rate, was reduced during exercise, but increased to resting levels immediately post-exercise, and was further increased at 3 h post-exercise (p < 0.05), but only during the CON trial. Exercise resulted in a marked suppression of whole-body protein synthesis (50% of rest; p < 0.05), which was restored post-exercise; however, the addition of glutamine did not affect whole-body protein synthesis post-exercise. The rate of MPS was not different between trials. The addition of glutamine to a CHO + EAA beverage had no effect on post-exercise muscle glycogen resynthesis or muscle protein synthesis, but may suppress a rise in whole-body proteolysis during the later stages of recovery.
authors.affiliation: Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4K1, Canada.
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Wilkinson
authors.forename: Paul L
authors.initials: PL
authors.lastname: Kim
authors.forename: David
authors.initials: D
authors.lastname: Armstrong
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Phillips
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood; D000601:Amino Acids, Essential / Q000008:administration & dosage*; D001628:Beverages; D001707:Biopsy, Needle; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D015444:Exercise / Q000502:physiology*; D005973:Glutamine / Q000008:administration & dosage*; D006003:Glycogen / Q000032:analysis / Q000096:biosynthesis; D006801:Humans; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D010101:Oxygen Consumption; D011506:Proteins / Q000378:metabolism; D013177:Sports / Q000502:physiology*
chemical_list: D000596:Amino Acids; D000601:Amino Acids, Essential; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D009124:Muscle Proteins; D011506:Proteins; D005973:Glutamine; D006003:Glycogen