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Short inter-set rest blunts resistance exercise-induced increases in myofibrillar protein synthesis and intracellular signalling in young males

Authors

  • James McKendry,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Alberto Pérez-López,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. Departamento de Medicina, Universidad de Alcalá, Spain
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  • Michael McLeod,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Dan Luo,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Jessica R. Dent,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Benoit Smeuninx,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Jinglei Yu,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
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  • Angela E. Taylor,

    1. School of Clinical and Experimental Medicine, University of Birmingham, UK
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  • Andrew Philp,

    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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  • Leigh Breen

    Corresponding author
    1. School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
    2. MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
    • Corresponding author L. Breen: School of Sport, Exercise and Rehabilitation Sciences, MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.   Email: l.breen@bham.ac.uk

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New Findings

  • What is the central question of this study?

    Does shorter rest between sets of resistance exercise promote a superior circulating hormonal and acute muscle anabolic response compared with longer rest periods?

  • What is the main finding and its importance?

    We demonstrate that short rest (1 min) between sets of moderate-intensity, high-volume resistance exercise blunts the acute muscle anabolic response compared with a longer rest period (5 min), despite a superior circulating hormonal milieu. These data have important implications for the development of training regimens to maximize muscle hypertrophy.

Manipulating the rest-recovery interval between sets of resistance exercise may influence training-induced muscle remodelling. The aim of this study was to determine the acute muscle anabolic response to resistance exercise performed with short or long inter-set rest intervals. In a study with a parallel-group design, 16 males completed four sets of bilateral leg-press and knee-extension exercise at 75% of one-repetition maximum to momentary muscular failure, followed by ingestion of 25 g of whey protein. Resistance exercise sets were interspersed by 1 min (n = 8) or 5 min of passive rest (n = 8). Muscle biopsies were obtained at rest, 0, 4, 24 and 28 h postexercise during a primed continuous infusion of l-[ring-13C6]phenylalanine to determine myofibrillar protein synthesis and intracellular signalling. We found that the rate of myofibrillar protein synthesis increased above resting values from 0 to 4 h postexercise with 1 (76%; P = 0.047) and 5 min inter-set rest (152%; P < 0.001) and was significantly greater in the 5 min inter-set rest group (P = 0.001). Myofibrillar protein synthesis rates at 24–28 h postexercise remained elevated above resting values (P < 0.05) and were indistinguishable between groups. Postexercise p70S6KThr389 and rpS6Ser240/244 phosphorylation were reduced with 1 compared with 5 min inter-set rest, whereas phosphorylation of eEF2Thr56, TSC2Thr1462, AMPKThr172 and REDD1 protein were greater for 1 compared with 5 min inter-set rest. Serum testosterone was greater at 20–40 min postexercise and plasma lactate greater immediately postexercise for 1 versus 5 min inter-set rest. Resistance exercise with short (1 min) inter-set rest duration attenuated myofibrillar protein synthesis during the early postexercise recovery period compared with longer (5 min) rest duration, potentially through compromised activation of intracellular signalling.

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