title: Resistance exercise volume affects myofibrillar protein synthesis and anabolic signalling molecule phosphorylation in young men.
abstract: We aimed to determine if any mechanistic differences exist between a single set (1SET) and multiple sets (i.e. 3 sets; 3SET) of resistance exercise by utilizing a primed constant infusion of [ring-13C6]phenylalanine to determine myofibrillar protein synthesis (MPS) and Western blot analysis to examine anabolic signalling molecule phosphorylation following an acute bout of resistance exercise. Eight resistance-trained men (24+/-5 years, BMI=25+/-4 kg m2) were randomly assigned to perform unilateral leg extension exercise at 70% concentric one repetition maximum (1RM) until volitional fatigue for 1SET or 3SET. Biopsies from the vastus lateralis were taken in the fasted state (Fast) and fed state (Fed; 20 g of whey protein isolate) at rest, 5 h Fed, 24 h Fast and 29 h Fed post-exercise. Fed-state MPS was transiently elevated above rest at 5 h for 1SET (2.3-fold) and returned to resting levels by 29 h post-exercise. However, the exercise induced increase in MPS following 3SET was superior in amplitude and duration as compared to 1SET at both 5 h (3.1-fold above rest) and 29 h post-exercise (2.3-fold above rest). Phosphorylation of 70 kDa S6 protein kinase (p70S6K) demonstrated a coordinated increase with MPS at 5 h and 29 h post-exercise such that the extent of p70S6K phosphorylation was related to the MPS response (r=0.338, P=0.033). Phosphorylation of 90 kDa ribosomal S6 protein kinase (p90RSK) and ribosomal protein S6 (rps6) was similar for 1SET and 3SET at 24 h Fast and 29 h Fed, respectively. However, 3SET induced a greater activation of eukaryotic translation initiation factor 2B (eIF2B) and rpS6 at 5 h Fed. These data suggest that 3SET of resistance exercise is more anabolic than 1SET and may lead to greater increases in myofibrillar protein accretion over time.
authors.affiliation: Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Burd
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Holwerda
authors.forename: Keegan C
authors.initials: KC
authors.lastname: Selby
authors.forename: Daniel W D
authors.initials: DW
authors.lastname: West
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Staples
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Cain
authors.forename: Joshua G A
authors.initials: JG
authors.lastname: Cashaback
authors.forename: James R
authors.initials: JR
authors.lastname: Potvin
authors.forename: Steven K
authors.initials: SK
authors.lastname: Baker
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Phillips
mesh_terms: D000328:Adult; D001706:Biopsy; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D004576:Electromyography; D020717:Eukaryotic Initiation Factor-2B / Q000378:metabolism; D005215:Fasting; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D018763:Muscle Fatigue; D009124:Muscle Proteins / Q000096:biosynthesis*; D009210:Myofibrils / Q000378:metabolism*; D010649:Phenylalanine / Q000008:administration & dosage / Q000097:blood; D010766:Phosphorylation; D019518:Postprandial Period; D052097:Quadriceps Muscle / Q000378:metabolism*; D055070:Resistance Training; D038601:Ribosomal Protein S6 / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D020717:Eukaryotic Initiation Factor-2B; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D038601:Ribosomal Protein S6; D010649:Phenylalanine; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D038744:Ribosomal Protein S6 Kinases, 90-kDa