Early- and later-phases satellite cell responses and myonuclear content with resistance training in young men

PLoS One. 2018 Jan 11;13(1):e0191039. doi: 10.1371/journal.pone.0191039. eCollection 2018.

Abstract

Satellite cells (SC) are associated with skeletal muscle remodelling after muscle damage and/or extensive hypertrophy resulting from resistance training (RT). We recently reported that early increases in muscle protein synthesis (MPS) during RT appear to be directed toward muscle damage repair, but MPS contributes to hypertrophy with progressive muscle damage attenuation. However, modulations in acute-chronic SC content with RT during the initial (1st-wk: high damage), early (3rd-wk: attenuated damage), and later (10th-wk: no damage) stages is not well characterized. Ten young men (27 ± 1 y, 23.6 ± 1.0 kg·m-2) underwent 10-wks of RT and muscle biopsies (vastus-lateralis) were taken before (Pre) and post (48h) the 1st (T1), 5th (T2) and final (T3) RT sessions to evaluate fibre type specific SC content, cross-sectional area (fCSA) and myonuclear number by immunohistochemistry. We observed RT-induced hypertrophy after 10-wks of RT (fCSA increased ~16% in type II, P < 0.04; ~8% in type I [ns]). SC content increased 48h post-exercise at T1 (~69% in type I [P = 0.014]; ~42% in type II [ns]), and this increase was sustained throughout RT (pre T2: ~65%, ~92%; pre T3: ~30% [ns], ~87%, for the increase in type I and II, respectively, vs. pre T1 [P < 0.05]). Increased SC content was not coupled with changes in myonuclear number. SC have a more pronounced role in muscle repair during the initial phase of RT than muscle hypertrophy resulted from 10-wks RT in young men. Chronic elevated SC pool size with RT is important providing proper environment for future stresses or larger fCSA increases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cell Nucleus / metabolism*
  • Humans
  • Male
  • Muscle Proteins / metabolism*
  • Satellite Cells, Skeletal Muscle / metabolism
  • Satellite Cells, Skeletal Muscle / physiology*
  • Weight Lifting*

Substances

  • Muscle Proteins

Grants and funding

The present study was funded by the São Paulo Research Foundation (FAPESP) grants (#2013/21218-4 to CAL) and Natural Science and Engineering Research Council (NSERC) of Canada (RGPIN-2015-04613 to SMP). SMP also acknowledges support from the Canada Research Chairs program. FD was supported by FAPESP grants (#2012/24499-1, #2014/19594-0, and #2016/24259-1). CU, HR and VT are supported by the National Council for Scientific and Technological Development (CNPq) grant (CU: #303085/2015-0 and #448387/2014-0; HR: #307023/2014-1; VT: #310823/2013-7). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.