Sprint exercise enhances skeletal muscle p70S6k phosphorylation and more so in women than in men

Authors

  • M. Esbjörnsson,

    Corresponding author
    1. Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
    • Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
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  • H. C. Rundqvist,

    1. Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
    2. Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
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  • H. Mascher,

    1. Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
    2. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
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  • T. Österlund,

    1. Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
    2. Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
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  • O. Rooyackers,

    1. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
    2. Division of Anesthesiology and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
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  • E. Blomstrand,

    1. Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
    2. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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  • E. Jansson

    1. Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
    2. Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden
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Correspondence: M. Esbjörnsson, Division of Clinical Physiology, Karolinska University Hospital, Huddinge, SE-141 86 Stockholm, Sweden. E-mail: mona.esbjornsson@ki.se

Abstract

Aim:

Sprint exercise is characterized by repeated sessions of brief intermittent exercise at a high relative workload. However, little is known about the effect on mTOR pathway, an important link in the regulation of muscle protein synthesis. An earlier training study showed a greater increase in muscle fibre cross-sectional area in women than men. Therefore, we tested the hypothesis that the activation of mTOR signalling is more pronounced in women than in men. Healthy men (n = 9) and women (n = 8) performed three bouts of 30-s sprint exercise with 20-min rest in between.

Methods:

Multiple blood samples were collected over time, and muscle biopsy specimens were obtained at rest and 140 min after the last sprint.

Results:

Serum insulin increased by sprint exercise and more so in women than in men [gender (g) × time (t)]: = 0.04. In skeletal muscle, phosphorylation of Akt increased by 50% (t, = 0.001) and mTOR by 120% (t, = 0.002) independent of gender. The elevation in p70S6k phosphorylation was larger in women (g × t, = 0.03) and averaged 230% (= 0.006) as compared to 60% in men (= 0.04). Phosphorylation rpS6 increased by 660% over time independent of gender (t, = 0.003). Increase in the phosphorylation of p70S6k was directly related to increase in serum insulin (r = 0.68, = 0.004).

Conclusion:

It is concluded that repeated 30-s all-out bouts of sprint exercise separated by 20 min of rest increases Akt/mTOR signalling in skeletal muscle. Secondly, signalling downstream of mTOR was stronger in women than in men after sprint exercise indicated by the increased phosphorylation of p70S6k.

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