TY - JOUR T1 - Ribosome biogenesis adaptation and mTORC1 signalling in human skeletal muscle following concurrent training compared with resistance training alone JF - bioRxiv DO - 10.1101/115212 SP - 115212 AU - Jackson J. Fyfe AU - David J. Bishop AU - Jonathan D. Bartlett AU - Erik D. Hanson AU - Mitchell J. Anderson AU - Andrew P. Garnham AU - Nigel K. Stepto Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/03/08/115212.abstract N2 - Combining RT with endurance training (i.e., concurrent training) may attenuate skeletal muscle hypertrophy consequent to RT; however, the underlying mechanisms are unclear. We investigated whether markers of ribosome biogenesis, a process linked with skeletal muscle hypertrophy, are attenuated following concurrent training vs. RT alone. Twenty-three males (mean ± SD: age, 29.6 ± 5.5 y; V̇O2peak, 44 ± 11 mL-kg−1min−1) underwent 8 wk (3 sessions-wk−1) of either: 1) HIT (high-intensity interval training) combined with RT (HIT+RT group, n=8), 2) work-matched MICT (moderate-intensity continuous training) combined with RT (MICT+RT group, n=7), or 3) RT alone (RT group, n=8). Vastus lateralis biopsies were obtained before training, and immediately before, 1 h and 3 h after the final training session. Type I muscle fibre cross-sectional area (CSA) was further increased by RT vs. HIT+RT (34 ±22%; ES, 1.03 ±0.80), but not vs. MICT+RT (15 ±54%; ES, 0.39 ±1.45). Basal training-induced changes in expression of the 45S ribosomal RNA (rRNA) precursor, and 5.8S and 28S mature rRNAs were greater for concurrent exercise vs. RT, largely because of trends for reduced rRNA expression following RT. During the final training session, RT further increased skeletal muscle mTORC1 signalling (p70S6K1 and rps6 phosphorylation) and signalling related to 45S rRNA transcription (TIF-1A and UBF phosphorylation) vs. concurrent exercise. Thus, when performed in a training-accustomed state, RT preferentially induces mTORC1 and ribosome biogenesis-related signalling in human skeletal muscle vs. concurrent exercise. However, changes in markers of skeletal muscle ribosome biogenesis were more favourable with concurrent training vs. RT.Table of contents category: MuscleKey points summaryRibosome biogenesis is an important process linked with human skeletal muscle growth following resistance training (RT); however, whether concurrent training alters skeletal muscle ribosome biogenesis compared with RT alone in unknownIn agreement with previous studies, concurrent training blunted the RT-induced increase in type I, but not type II, muscle fibre sizeDespite the attenuated muscle hypertrophy with concurrent training, changes in markers of skeletal muscle ribosome biogenesis were generally more favourable with concurrent training vs. RT performed aloneConversely, a single session of resistance exercise (RE) performed post-training was more potent for inducing signalling responses in skeletal muscle related to both ribosome biogenesis and the mTORC1 pathway, vs. concurrent exerciseRibosome biogenesis is therefore not compromised following short-term concurrent training; however, both mTORC1 and ribosome biogenesis-related signalling are attenuated in skeletal muscle following a single session of concurrent exercise performed in a training-accustomed state1-RMone-repetition maximum4E-BP1eukaryotic initiation factor 4E binding protein 1AMPK5’ adenosine monophosphate-activated protein kinaseβ2Mbeta-2 microglobulinCDKcyclin-dependent kinaseDXAdual-energy x-ray absorptiometryFox-O1forkhead box-O1GAPDHglyceraldehyde 3-phosphate dehydrogenaseHIThigh-intensity interval training cyclingLTlactate thresholdMICTmoderate-intensity continuous cyclingMPSmuscle protein synthesismRNAmessenger RNAmTORC1mechanistic target or rapamycin complex 1MuRF-1muscle RING-finger 1p70S6K170 kilodalton ribosomal protein subunit kinase 1PGC-1αperoxisome proliferator activated receptor gamma co-activator 1 alphaPOLR1Bpolymerase (RNA) 1 polypeptide BREresistance exerciseRPErating of perceived exertionrRNAribosomal ribonucleic acidRTresistance trainingSL-1selectivity factor-1TBPTATA binding proteinTIF-1ARRN3 polymerase 1 transcription factorUBFupstream binding factorV̇O2peakpeak volume of oxygen uptakeWpeakpeak aerobic power. ER -