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Myofibre hypertrophy in the absence of changes to satellite cell content following concurrent exercise training in young healthy men
Shamim, Baubak Camera, Donny M. Whitfield, Jamie
Shamim, Baubak
Camera, Donny M.
Whitfield, Jamie
Abstract
Concurrent exercise training has been suggested to create an ‘interference effect,’ attenuating resistance training-based skeletal muscle adaptations, including myofibre hypertrophy. Satellite cells support myofibre hypertrophy and are influenced by exercise mode. To determine whether satellite cells contribute to the ‘interference effect’ changes in satellite cell and myonuclear content were assessed following a period of training in 32 recreationally active males (age: 25 ± 5 year; body mass index: 24 ± 3 kg⋅m–2; mean ± SD) who undertook 12-week of either isolated (3 d⋅w–1) resistance (RES; n = 10), endurance (END; n = 10), or alternate day (6 d⋅w–1) concurrent (CET, n = 12) training. Skeletal muscle biopsies were obtained pre-intervention and after 2, 8, and 12 weeks of training to determine fibre type-specific cross-sectional area (CSA), satellite cell content (Pax7+DAPI+), and myonuclei (DAPI+) using immunofluorescence microscopy. After 12 weeks, myofibre CSA increased in all training conditions in type II (P = 0.0149) and mixed fibres (P = 0.0102), with no difference between conditions. Satellite cell content remained unchanged after training in both type I and type II fibres. Significant correlations were observed between increases in fibre type-specific myonuclear content and CSA of Type I (r = 0.63, P < 0.0001), Type II (r = 0.69, P < 0.0001), and mixed fibres (r = 0.72, P < 0.0001). Resistance, endurance, and concurrent training induce similar myofibre hypertrophy in the absence of satellite cell and myonuclear pool expansion. These findings suggest that myonuclear accretion via satellite cell fusion is positively correlated with hypertrophy after 12 weeks of concurrent training, and that individuals with more myonuclear content displayed greater myofibre hypertrophy.
Keywords
concurrent exercise, resistance exercise, endurance exercise, skeletal muscle, satellite cells
Date
2021
Type
Journal article
Journal
Frontiers in Physiology
Book
Volume
12
Issue
Page Range
1-13
Article Number
Article 625044
ACU Department
School of Behavioural and Health Sciences
Faculty of Health Sciences
Non-faculty
Centre for Exercise and Nutrition
Faculty of Health Sciences
Non-faculty
Centre for Exercise and Nutrition
Relation URI
Source URL
Event URL
Open Access Status
Published as ‘gold’ (paid) open access
License
CC BY 4.0
File Access
Open