Abstract
Mitochondria are critical to skeletal muscle contractile function and metabolic health. Short-term periods of step reduction (SR) are associated with alterations in muscle protein turnover and mass. However, the effects of SR on mitochondrial metabolism/muscle oxidative metabolism and insulin-mediated signaling are unclear. We tested the hypothesis that the total and/or phosphorylated protein content of key skeletal muscle markers of mitochondrial/oxidative metabolism, and insulin-mediated signaling would be altered over 7 days of SR in young healthy males. Eleven, healthy, recreationally active males (means ± SE, age: 22 ± 1 yr, BMI: 23.4 ± 0.7 kg·m 2) underwent a 7-day period of SR. Immediately before and following SR, fasted-state muscle biopsy samples were acquired and analyzed for the assessment of total and phosphorylated protein content of key markers of mitochondrial/oxidative metabolism and insulin-mediated signaling. Daily step count was significantly reduced during the SR intervention (13,054 ± 833 to 1,192 ± 99 steps·day -1, P < 0.001). Following SR, there was a significant decline in maximal citrate synthase activity (fold change: 0.94 ± 0.08, P < 0.05) and a significant increase in the protein content of p-glycogen synthase (P-GS S641; fold change: 1.47 ± 0.14, P < 0.05). No significant differences were observed in the total or phosphorylated protein content of other key markers of insulin-mediated signaling, oxidative metabolism, mitochondrial function, or mitochondrial dynamics (all P > 0.05). These results suggest that short-term SR reduces the maximal activity of citrate synthase, a marker of mitochondrial content, without altering the total or phosphorylated protein content of key markers of skeletal muscle mitochondrial metabolism and insulin signaling in young healthy males.
Original language | English |
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Pages (from-to) | 1653-1662 |
Number of pages | 10 |
Journal | Journal of Applied Physiology |
Volume | 131 |
Issue number | 6 |
Early online date | 4 Nov 2021 |
DOIs | |
Publication status | Published - 1 Dec 2021 |
Bibliographical note
Funding Information:This work was supported by a studentship (to S.J.E) from the BBSRC Midlands Integrative Biosciences Training Partnership and a Exercise as Medicine studentship (to B.J.S) from the College of Life and Environmental Sciences, University of Birmingham.
Publisher Copyright:
Copyright © 2021 The Authors. Licensed under Creative Commons Attribution CC-BY 4.0.
Keywords
- Insulin sensitivity
- Mitochondria
- Physical inactivity
- Skeletal muscle
- Step reduction
ASJC Scopus subject areas
- Physiology
- Physiology (medical)