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Comparative Study
. 2012 Jul;205(3):411-22.
doi: 10.1111/j.1748-1716.2012.02404.x. Epub 2012 Jan 23.

Sprint Exercise Enhances Skeletal Muscle p70S6k Phosphorylation and More So in Women Than in Men

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Comparative Study

Sprint Exercise Enhances Skeletal Muscle p70S6k Phosphorylation and More So in Women Than in Men

M Esbjörnsson et al. Acta Physiol (Oxf). .

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