Post-exercise protein synthesis rates are only marginally higher in type I compared with type II muscle fibres following resistance-type exercise.

R. Koopman, B.G. Gleeson, A.P. Gijsen, B.B.L. Groen, J.M.G. Senden, M.J. Rennie, L.J.C. van Loon

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Abstract

We examined the effect of an acute bout of resistance exercise on fractional muscle protein synthesis rates in human type I and type II muscle fibres. After a standardised breakfast (31 ± 1 kJ kg−1 body weight, consisting of 52 Energy% (En%) carbohydrate, 34 En% protein and 14 En% fat), 9 untrained men completed a lower-limb resistance exercise bout (8 sets of 10 repetitions leg press and leg extension at 70% 1RM). A primed, continuous infusion of l-[ring-13C6]phenylalanine was combined with muscle biopsies collected from both legs immediately after exercise and after 6 h of post-exercise recovery. Single muscle fibres were dissected from freeze-dried biopsies and stained for ATPase activity with pre-incubation at a pH of 4.3. Type I and II fibres were separated under a light microscope and analysed for protein-bound l-[ring-13C6]phenylalanine labelling. Baseline (post-exercise) l-[ring-13C6]phenylalanine muscle tissue labelling, expressed as (∂13C/12C), averaged −32.09 ± 0.28, −32.53 ± 0.10 and −32.02 ± 0.16 in the type I and II muscle fibres and mixed muscle, respectively (P = 0.14). During post-exercise recovery, muscle protein synthesis rates were marginally (8 ± 2%) higher in the type I than type II muscle fibres, at 0.100 ± 0.005 versus 0.094 ± 0.005%/h, respectively (P < 0.05), whereby rates of mixed muscle protein were 0.091 ± 0.005%/h. Muscle protein synthesis rates following resistance-type exercise are only marginally higher in type I compared with type II muscle fibres.
Original languageEnglish
Pages (from-to)1871-1878
Number of pages8
JournalEuropean Journal of Applied Physiology
Volume111
Issue number8
DOIs
Publication statusPublished - Aug 2011

Keywords

  • Skeletal muscle
  • Muscle fibre type
  • ATPase
  • FSR
  • Stable isotopes
  • HUMAN SKELETAL-MUSCLE
  • ACTOMYOSIN ATPASE
  • CO-INGESTION
  • AMINO-ACIDS
  • ELDERLY-MEN
  • FED STATE
  • PHOSPHORYLATION
  • LEUCINE
  • HUMANS
  • YOUNG

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