title: Co-ingestion of carbohydrate and whey protein increases fasted rates of muscle protein synthesis immediately after resistance exercise in rats.
abstract: The objective of the study was to investigate whether co-ingestion of carbohydrate and protein as compared with protein alone augments muscle protein synthesis (MPS) during early exercise recovery. Two months old rats performed 10 repetitions of ladder climbing with 75% of body weight attached to their tails. Placebo (PLA), whey protein (WP), or whey protein plus carbohydrate (CP) was then given to rats by gavage. An additional group of sedentary rats (SED) was used as controls. Blood samples were collected immediately and at either 1 or 2 h after exercise. The flexor hallucis longus muscle was excised at 1 or 2 h post exercise for analysis of MPS and related signaling proteins. MPS was significantly increased by CP compared with PLA (p<0.05), and approached significance compared with WP at 1 h post exercise (p = 0.08). CP yielded a greater phosphorylation of mTOR compared with SED and PLA at 1 h post exercise and SED and WP at 2 h post exercise. CP also increased phosphorylation of p70S6K compared with SED at 1 and 2 h post exercise. 4E-BP1 phosphorylation was inhibited by PLA at 1 h but elevated by WP and CP at 2 h post exercise relative to SED. The phosphorylation of AMPK was elevated by exercise at 1 h post exercise, and this elevated level was sustained only in the WP group at 2 h. The phosphorylation of Akt, GSK3, and eIF2Bε were unchanged by treatments. Plasma insulin was transiently increased by CP at 1 h post exercise. In conclusion, post-exercise CP supplementation increases MPS post exercise relative to PLA and possibly WP, which may have been mediated by greater activation of the mTOR signaling pathway.
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Wanyi
authors.initials: W
authors.lastname: Wang
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Solares
authors.affiliation: Department of Athletic Training and Exercise Physiology, Midwestern State University, Wichita Falls, Texas, United States of America.
authors.forename: Soon-Mi
authors.initials: SM
authors.lastname: Choi
authors.affiliation: Sports Science College, Beijing Sports University, Beijing, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Aram
authors.initials: A
authors.lastname: Yoon
authors.affiliation: Muscle Physiology Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Farrar
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002241:Carbohydrates / Q000008:administration & dosage*; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000378:metabolism; D010805:Physical Conditioning, Animal; D051381:Rats; D015398:Signal Transduction; D000067816:Whey Proteins / Q000008:administration & dosage*
chemical_list: D001786:Blood Glucose; D002241:Carbohydrates; D009124:Muscle Proteins; D000067816:Whey Proteins