Resistance exercise induced mTORC1 signaling is not impaired by subsequent endurance exercise in human skeletal muscle

Am J Physiol Endocrinol Metab. 2013 Jul 1;305(1):E22-32. doi: 10.1152/ajpendo.00091.2013. Epub 2013 Apr 30.


The current dogma is that the muscle adaptation to resistance exercise is blunted when combined with endurance exercise. The suggested mechanism (based on rodent experiments) is that activation of adenosine monophosphate-activated protein kinase (AMPK) during endurance exercise impairs muscle growth through inhibition of the mechanistic target of rapamycin complex 1 (mTORC1). The purpose of this study was to investigate potential interference of endurance training on the signaling pathway of resistance training [mTORC1 phosphorylation of ribosomal protein S6 kinase 1 (S6K1)] in human muscle. Ten healthy and moderately trained male subjects performed on two separate occasions either acute high-intensity and high-volume resistance exercise (leg press, R) or R followed by 30 min of cycling (RE). Muscle biopsies were collected before and 1 and 3 h post resistance exercise. Phosphorylation of mTOR (Ser²⁴⁴⁸) increased 2-fold (P < 0.05) and that of S6K1 (Thr³⁸⁹) 14-fold (P < 0.05), with no difference between R and RE. Phosphorylation of eukaryotic elongation factor 2 (eEF2, Thr⁵⁶) was reduced ~70% during recovery in both trials (P < 0.05). An interesting finding was that phosphorylation of AMPK (Thr¹⁷²) and acetyl-CoA carboxylase (ACC, Ser⁷⁹) decreased ~30% and ~50%, respectively, 3 h postexercise (P < 0.05). Proliferator-activated receptor-γ coactivator-1 (PGC-1α) mRNA increased more after RE (6.5-fold) than after R (4-fold) (RE vs. R: P < 0.01) and was the only gene expressed differently between trials. These data show that the signaling of muscle growth through the mTORC1-S6K1 axis after heavy resistance exercise is not inhibited by subsequent endurance exercise. It is also suggested that prior activation of mTORC1 signaling may repress subsequent phosphorylation of AMPK.

Keywords: adenosine monophosphate-activated protein kinase; interference; mechanistic target of rapamycin complex 1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Adenylate Kinase / metabolism
  • Adult
  • Exercise / physiology
  • Humans
  • Male
  • Mechanistic Target of Rapamycin Complex 1
  • Mitochondria / physiology
  • Multiprotein Complexes
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / physiology*
  • Phosphorylation / physiology
  • Physical Endurance / physiology*
  • Proteins / genetics
  • Proteins / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism
  • RNA, Messenger / metabolism
  • Resistance Training
  • Ribosomal Protein S6 Kinases, 70-kDa / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism*
  • Signal Transduction / physiology*
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Young Adult


  • Adaptor Proteins, Signal Transducing
  • DDIT4 protein, human
  • DDIT4L protein, human
  • Multiprotein Complexes
  • Proteins
  • Proto-Oncogene Proteins c-myc
  • RNA, Messenger
  • Transcription Factors
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • AKT1 protein, human
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases, 70-kDa
  • ribosomal protein S6 kinase, 70kD, polypeptide 1
  • Adenylate Kinase