Concurrent exercise incorporating high-intensity interval or continuous training modulates mTORC1 signaling and microRNA expression in human skeletal muscle.
We compared the effects of concurrent exercise, incorporating either high-intensity interval training (HIT) or moderate-intensity continuous training (MICT), on mechanistic target of rapamycin complex 1 (mTORC1) signaling and microRNA expression in skeletal muscle, relative to resistance exercise (RE) alone. Eight males (mean ± SD: age, 27 ± 4 yr; V̇o2 peak , 45.7 ± 9 ml·kg(-1)·min(-1)) performed three experimental trials in a randomized order: 1) RE (8 × 5 leg press repetitions at 80% 1-repetition maximum) performed alone and RE preceded by either 2) HIT cycling [10 × 2 min at 120% lactate threshold (LT); HIT + RE] or 3) work-matched MICT cycling (30 min at 80% LT; MICT + RE). Vastus lateralis muscle biopsies were obtained immediately before RE, either without (REST) or with (POST) preceding endurance exercise and +1 h (RE + 1 h) and +3 h (RE + 3 h) after RE. Prior HIT and MICT similarly reduced muscle glycogen content and increased ACC(Ser79) and p70S6K(Thr389) phosphorylation before subsequent RE (i.e., at POST). Compared with MICT, HIT induced greater mTOR(Ser2448) and rps6(Ser235/236) phosphorylation at POST. RE-induced increases in p70S6K and rps6 phosphorylation were not influenced by prior HIT or MICT; however, mTOR phosphorylation was reduced at RE + 1 h for MICT + RE vs. both HIT + RE and RE. Expression of miR-133a, miR-378, and miR-486 was reduced at RE + 1 h for HIT + RE vs. both MICT + RE and RE. Postexercise mTORC1 signaling following RE is therefore not compromised by prior HIT or MICT, and concurrent exercise incorporating HIT, but not MICT, reduces postexercise expression of miRNAs implicated in skeletal muscle adaptation to RE.
Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia; College of Sport and Exercise Science, Victoria University, Melbourne, Australia; and.
Jackson J
JJ
Fyfe
Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia; College of Sport and Exercise Science, Victoria University, Melbourne, Australia; and.
David J
DJ
Bishop
Centre for Physical Activity and Nutrition Research, School of Nutrition and Exercise Sciences, Deakin University, Melbourne, Australia.
Evelyn
E
Zacharewicz
Centre for Physical Activity and Nutrition Research, School of Nutrition and Exercise Sciences, Deakin University, Melbourne, Australia.
Aaron P
AP
Russell
Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia; College of Sport and Exercise Science, Victoria University, Melbourne, Australia; and nigel.stepto@vu.edu.au.
Nigel K
NK
Stepto
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D035683:MicroRNAs / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000379:methods; D010807:Physical Endurance / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D015398:Signal Transduction / Q000502:physiology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
D035683:MicroRNAs; D046912:Multiprotein Complexes; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
concurrent training; continuous training; exercise intensity; high-intensity interval training; interference