Resistance training variable manipulations are less relevant than intrinsic biology in affecting muscle fiber hypertrophy

• DOI: 10.1111/sms.14134
• Publication Date: 2022-01-29T04:00:11Z
• Authors: Vitor Angleri; Felipe Damas; Stuart M. Phillips; Heloisa Sobreiro ...; Anabelle Silva Co...; Uliana Sbeguen St...; Natalia Santanielo; Samuel Domingos S...; Luiz Augusto Rian...; Manoel Emílio Lix...; Miguel Soares Con...; Felipe Cassaro Ve...; Carlos Ugrinowitsch; Cleiton Augusto L...
• Keywords: Muscle fibre

We aimed to investigate whether muscle fiber cross-sectional area (fCSA) and associated molecular processes could be differently affected at the group individual level by manipulating resistance training (RT) variables. Twenty resistance-trained subjects had each leg randomly allocated either a standard RT (RT-CON: without specific variables manipulations) or variable (RT-VAR: manipulation of load, volume, action, rest interval session). Muscle fCSA, satellite cell (SC) pool, myonuclei content, gene expression were assessed before after (chronic effect). Gene was 24 h last session (acute RT-CON RT-VAR increased fCSA domain in type I II fibers (p < 0.05). SC content did not change for both conditions > Pax-7, MyoD, MMP-2 COL3A1 (chronic) MGF, MMP-9 (acute) similar The increase acute MyoG significantly higher than found significant correlation between changes (r = 0.89). also correlated cells 0.42) 0.50) changes. Heatmap analyses showed coupled SC, responses level, regardless protocol. high low within-subject variability protocol suggests that intrinsic biological factors seem more important explain magnitude gains subjects.