title: Effects of pre-exercise feeding on serum hormone concentrations and biomarkers of myostatin and ubiquitin proteasome pathway activity.
abstract: OBJECTIVE
  The aim of the study was to examine the acute effects of pre-exercise ingestion of protein, carbohydrate, and a non-caloric placebo on serum concentrations of insulin and cortisol, and the intramuscular gene expression of myostatin- and ubiquitin proteasome pathway (UPP)-related genes following a bout of resistance exercise.
  
  
  METHODS
  Ten untrained college-aged men participated in three resistance exercise sessions (3 × 10 at 80 % 1RM for bilateral hack squat, leg press, and leg extension) in a cross-over fashion, which were randomly preceded by protein, carbohydrate, or placebo ingestion 30 min prior to training. Pre-supplement/pre-exercise, 2 h and 6 h post-exercise muscle biopsies were obtained during each session and analyzed for mRNA fold changes in myostatin (MSTN), activin IIB, follistatin-like 3 (FSTL3), SMAD specific E3 ubiquitin protein ligase 1 (SMURF1), forkhead box O3, F-box protein 32 (FBXO32), and Muscle RING-finger protein-1, with beta-actin serving as the housekeeping gene. Gene expression of all genes was analyzed using real-time PCR.
  
  
  RESULTS
  Acute feeding appeared to have no significant effect on myostatin or UPP biomarkers. However, resistance exercise resulted in a significant downregulation of MSTN and FBXO32 mRNA expression and a significant upregulation in FSTL3 and SMURF1 mRNA expression (p < 0.05).
  
  
  CONCLUSIONS
  An acute bout of resistance exercise results in acute post-exercise alterations in intramuscular mRNA expression of myostatin and UPP markers suggestive of skeletal muscle growth. However, carbohydrate and protein feeding surrounding resistance exercise appear to have little influence on the acute expression of these markers.
authors.affiliation: Faculty of Sciences, Engineering and Health, School of Medical and Applied Sciences, Institute for Health and Social Science Research, Central Queensland University, Rockhampton, QLD, Australia. v.dalbo@cqu.edu.au
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Dalbo
authors.forename: Michael D
authors.initials: MD
authors.lastname: Roberts
authors.forename: Scott
authors.initials: S
authors.lastname: Hassell
authors.forename: Chad M
authors.initials: CM
authors.lastname: Kerksick
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000097:blood*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D015536:Down-Regulation; D004435:Eating; D038702:Follistatin-Related Proteins / Q000235:genetics / Q000378:metabolism; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007328:Insulin / Q000097:blood*; D008297:Male; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D055435:Myostatin / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D055070:Resistance Training; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D016037:Single-Blind Method; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D000199:Actins; D015415:Biomarkers; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; C499517:FOXO3 protein, human; D038702:Follistatin-Related Proteins; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D007328:Insulin; C525911:MSTN protein, human; D009124:Muscle Proteins; D055435:Myostatin; D012333:RNA, Messenger; D000070584:Tripartite Motif Proteins; C498342:SMURF1 protein, human; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; C440908:TRIM63 protein, human; D044767:Ubiquitin-Protein Ligases; D006854:Hydrocortisone