title: Early time course of Akt phosphorylation after endurance and resistance exercise.
abstract: OBJECTIVE
  The aim of this study was to determine the early time course of exercise-induced signaling after divergent contractile activity associated with resistance and endurance exercise.
  
  
  METHODS
  Sixteen male subjects were randomly assigned to either a cycling (CYC; n = 8, 60 min, 70% V˙O2peak) or resistance (REX; n = 8, 8 x 5 leg extension, 80% one-repetition maximum, 3-min recovery) exercise group. Serial muscle biopsies were obtained from vastus lateralis at rest before, immediately after, and after 15, 30, and 60 min of passive recovery to determine early signaling responses after exercise.
  
  
  RESULTS
  There were comparable increases from rest in Akt(Thr308/Ser473) and mTOR(Ser2448) phosphorylation during the postexercise time course that peaked 30-60 min after both CYC and REX (P < 0.05). There were also similar patterns in p70S6K(Thr389) and 4E-BP1(Thr37/46) phosphorylation, but a greater magnitude of effect was observed for REX and CYC, respectively (P < 0.05). However, AMPK(Thr172) phosphorylation was only significantly elevated after CYC (P < 0.05), and we observed divergent responses for glycogen synthase(Ser641) and AS160 phosphorylation that were enhanced after CYC but not REX (P < 0.05).
  
  
  CONCLUSIONS
  We show a similar time course for Akt-mTOR-S6K phosphorylation during the initial 60-min recovery period after divergent contractile stimuli. Conversely, enhanced phosphorylation status of proteins that promote glucose transport and glycogen synthesis only occurred after endurance exercise. Our results indicate that endurance and resistance exercise initiate translational signaling, but high-load, low-repetition contractile activity failed to promote phosphorylation of pathways regulating glucose metabolism.
authors.affiliation: School of Medical Science, Health Innovations Research Institute, RMIT University, Melbourne, Australia.
authors.forename: Donny M
authors.initials: DM
authors.lastname: Camera
authors.forename: Johann
authors.initials: J
authors.lastname: Edge
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Short
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
authors.forename: Vernon G
authors.initials: VG
authors.lastname: Coffey
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000032:analysis; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism / Q000502:physiology; D018797:Cell Cycle Proteins; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006006:Glycogen Synthase / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism / Q000502:physiology; D019344:Lactic Acid / Q000097:blood / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D010807:Physical Endurance / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D055070:Resistance Training; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000032:analysis
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001786:Blood Glucose; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; D020690:GTPase-Activating Proteins; D007328:Insulin; D010750:Phosphoproteins; C518767:TBC1D4 protein, human; D019344:Lactic Acid; D006006:Glycogen Synthase; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases