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Cited by 82Muscle metabolism and nutritionSports Performance and TrainingMuscle Physiology and Disorders

Endurance Exercise Enhances the Effect of Strength Training on Muscle Fiber Size and Protein Expression of Akt and mTOR

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Kazior, Zuzanna, Willis, Sarah J., Moberg, Marcus, Apró, William, Calbet, José A. L., Holmberg, Hans-Christer, Blomstrand, Eva·2016·PLOS ONE
DOI 10.1371/journal.pone.0149082PMC PMC4757413
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Abstract

Reports concerning the effect of endurance exercise on the anabolic response to strength training have been contradictory. This study re-investigated this issue, focusing on training effects on indicators of protein synthesis and degradation. Two groups of male subjects performed 7 weeks of resistance exercise alone (R; n = 7) or in combination with preceding endurance exercise, including both continuous and interval cycling (ER; n = 9). Muscle biopsies were taken before and after the training period. Similar increases in leg-press 1 repetition maximum (30%; P<0.05) were observed in both groups, whereas maximal oxygen uptake was elevated (8%; P<0.05) only in the ER group. The ER training enlarged the areas of both type I and type II fibers, whereas the R protocol increased only the type II fibers. The mean fiber area increased by 28% (P<0.05) in the ER group, whereas no significant increase was observed in the R group. Moreover, expression of Akt and mTOR protein was enhanced in the ER group, whereas only the level of mTOR was elevated following R training. Training-induced alterations in the levels of both Akt and mTOR protein were correlated to changes in type I fiber area (r = 0.55-0.61, P<0.05), as well as mean fiber area (r = 0.55-0.61, P<0.05), reflecting the important role played by these proteins in connection with muscle hypertrophy. Both training regimes reduced the level of MAFbx protein (P<0.05) and tended to elevate that of MuRF-1. The present findings indicate that the larger hypertrophy observed in the ER group is due more to pronounced stimulation of anabolic rather than inhibition of catabolic processes.

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  • When exhaustive endurance exercise (such as high-intensity interval training or prolonged cycling) is performed in close temporal proximity to resistance training, the profound depletion of intramuscular glycogen and elevation of the AMP:ATP ratio robustly activate AMPK.

    “When exhaustive endurance exercise (such as high-intensity interval training or prolonged cycling) is performed in close temporal proximity to resistance training, the profound depletion of intramuscular glycogen and elevation of the AMP:ATP ratio robustly activate AMPK [134,135].”

    From Ribosome Biogenesis as a Putative Bottleneck to Skeletal Muscle Hypertrophy: Mechanisms, Human Evidence, and Practical Modulators (2026) · cites this paper as [135]

    The Introduction says endurance exercise can elevate AMPK activity before a subsequent resistance session, and Materials and Methods (The training program) says high-intensity cycling intervals were included to enhance AMPK activation. Neither passage attributes that activation to profound intramuscular glycogen depletion or an elevated AMP:ATP ratio, or establishes that it occurs robustly under the stated conditions. (LLM, conf=0.86)

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Authors
Kazior, Z., Willis, S. J., Moberg, M., Apró, W., Calbet, J. A. L., Holmberg, H.-C., & Blomstrand, E.
Affiliations
  • Mid Sweden University (SE)
  • Swedish School of Sport and Health Sciences (SE)
  • Universidad de Las Palmas de Gran Canaria (ES)
Corresponding author
Blomstrand, Eva
ORCID
Venue
PLOS ONE
Publisher
Public Library of Science (PLoS)
Published
2016-02-17
Volume
11
Issue
2
Pages
e0149082
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0149082
PMC
PMC4757413
OpenAlex
W2280626006
Cited by
82
References
65
Citations by year
2026: 7 · 2025: 7 · 2024: 7 · 2023: 6 · 2022: 12 · 2021: 10 · 2020: 4 · 2019: 6 · 2018: 10 · 2017: 10 · 2016: 3
FWCI
6.63
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Publications (Mid Sweden University) (submittedVersion, other-oa)
  • Acceda (Universidad de Las Palmas de Gran Canaria) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
Keywords
endurance exercise, resistance training, muscle fiber size, Akt, mTOR, muscle hypertrophy, protein synthesis, protein degradation, atrogin-1, MuRF1, type I muscle fibers, fast-twitch muscle, VO2max
MeSH terms
Adult, Biopsy, Humans, Male, Muscle Proteins, Oxygen Consumption, Physical Endurance, RNA, Messenger, Signal Transduction, Exercise, Muscle Fibers, Skeletal, Proto-Oncogene Proteins c-akt, Muscle Strength, Resistance Training, TOR Serine-Threonine Kinases

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