title: Early signaling responses to divergent exercise stimuli in skeletal muscle from well-trained humans.
abstract: Skeletal muscle from strength- and endurance-trained individuals represents diverse adaptive states. In this regard, AMPK-PGC-1alpha signaling mediates several adaptations to endurance training, while up-regulation of the Akt-TSC2-mTOR pathway may underlie increased protein synthesis after resistance exercise. We determined the effect of prior training history on signaling responses in seven strength-trained and six endurance-trained males who undertook 1 h cycling at 70% VO2peak or eight sets of five maximal repetitions of isokinetic leg extensions. Muscle biopsies were taken at rest, immediately and 3 h postexercise. AMPK phosphorylation increased after cycling in strength-trained (54%; P<0.05) but not endurance-trained subjects. Conversely, AMPK was elevated after resistance exercise in endurance- (114%; P<0.05), but not strength-trained subjects. Akt phosphorylation increased in endurance- (50%; P<0.05), but not strength-trained subjects after cycling but was unchanged in either group after resistance exercise. TSC2 phosphorylation was decreased (47%; P<0.05) in endurance-trained subjects following resistance exercise, but cycling had little effect on the phosphorylation state of this protein in either group. p70S6K phosphorylation increased in endurance- (118%; P<0.05), but not strength-trained subjects after resistance exercise, but was similar to rest in both groups after cycling. Similarly, phosphorylation of S6 protein, a substrate for p70 S6K, was increased immediately following resistance exercise in endurance- (129%; P<0.05), but not strength-trained subjects. In conclusion, a degree of "response plasticity" is conserved at opposite ends of the endurance-hypertrophic adaptation continuum. Moreover, prior training attenuates the exercise specific signaling responses involved in single mode adaptations to training.
authors.affiliation: School of Medical Sciences, RMIT University, Victoria, Australia.
authors.forename: Vernon G
authors.initials: VG
authors.lastname: Coffey
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Zhong
authors.forename: Anthony
authors.initials: A
authors.lastname: Shield
authors.forename: Benedict J
authors.initials: BJ
authors.lastname: Canny
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Chibalin
authors.forename: Juleen R
authors.initials: JR
authors.lastname: Zierath
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
mesh_terms: D055372:AMP-Activated Protein Kinases; D000328:Adult; D020717:Eukaryotic Initiation Factor-2B / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D010809:Physical Fitness / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D020717:Eukaryotic Initiation Factor-2B; D006360:Heat-Shock Proteins; D009097:Multienzyme Complexes; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C000624653:TSC2 protein, human; D014157:Transcription Factors; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases