title: Exercise type and volume alter signaling pathways regulating skeletal muscle glucose uptake and protein synthesis.
abstract: OBJECTIVE
  The aim of this study was to compare activation of cellular signaling pathways regulating protein synthesis and glucose uptake in skeletal muscle between resistance and endurance exercise. Moreover, the effect of resistance exercise volume was examined.
  
  
  METHODS
  Three groups of male volunteers (26 ± 3 years) were examined: 5 × 10 repetition maximum (RM) resistance exercise (RE) with leg press device (5 × 10 RE; n = 8), 10 × 10 RE (n = 11), and endurance exercise (strenuous 50-min walking with extra load on a treadmill; EE; n = 8). Muscle biopsies were obtained from m.vastus lateralis 30 min pre- and post-exercise.
  
  
  RESULTS
  Downstream markers of mTORC1, p-p70S6K(Thr421/Ser424) and p-rpS6(Ser240/244), increased more after 10 × 10 RE than after 5 × 10 RE (p < 0.05) and EE (p < 0.01-0.001). Exercise-induced changes in p-IRS-I(Ser636/639) that inhibit IRS-I signaling via negative feedback from hyperactivated mTORC1 signaling were greater (p < 0.05) after 10 × 10 RE compared with 5 × 10 RE and EE. The changes in energy sensor p-AMPKα(Thr172) were greater after 10 × 10 RE and EE (p < 0.05-0.01) than after 5 × 10 RE. A major regulator of glucose uptake in muscle, p-AS160(Thr642), increased more after 10 × 10 RE than after 5 × 10 RE (p < 0.01) and EE (p < 0.05).
  
  
  CONCLUSIONS
  10 × 10 RE induced greater activation of important signaling proteins regulating glucose uptake (p-AS160) and protein synthesis (p-p70S6K, p-rpS6) than 5 × 10 RE and EE. The present findings further suggest that, especially after 10 × 10 RE, IRS-I signaling is downregulated and that AS160 is activated through AMPK signaling pathway.
authors: Department of Biology of Physical Activity, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland, juha.ahtiainen@jyu.fi.
authors: Juha P
authors: JP
authors: Ahtiainen
authors: Simon
authors: S
authors: Walker
authors: Mika
authors: M
authors: Silvennoinen
authors: Heikki
authors: H
authors: Kyröläinen
authors: Bradley C
authors: BC
authors: Nindl
authors: Keijo
authors: K
authors: Häkkinen
authors: Kai
authors: K
authors: Nyman
authors: Harri
authors: H
authors: Selänne
authors: Juha J
authors: JJ
authors: Hulmi
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D015444:Exercise / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D014176:Protein Biosynthesis / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D009124:Muscle Proteins; D005947:Glucose