Ribosome accumulation during early phase resistance training in humans

Abstract

Aim To describe ribosome biogenesis during resistance training, its relation to training volume and muscle growth. Methods A training group (n = 11) performed 12 sessions (3‐4 sessions per week) of unilateral knee extension with constant and variable volume (6 and 3‐9 sets per session respectively) allocated to either leg. Ribosome abundance and biogenesis markers were assessed from vastus lateralis biopsies obtained at baseline, 48 hours after sessions 1, 4, 5, 8, 9 and 12, and after eight days of de‐training, and from a control group (n = 8). Muscle thickness was measured before and after the intervention. Results Training led to muscle growth (3.9% over baseline values, 95% CrI: [0.2, 7.5] vs. control) with concomitant increases in total RNA, ribosomal RNA, upstream binding factor (UBF) and ribosomal protein S6 with no differences between volume conditions. Total RNA increased rapidly in response to the first four sessions (8.6% [5.6, 11.7] per session), followed by a plateau and peak values after session 8 (49.5% [34.5, 66.5] above baseline). Total RNA abundance was associated with UBF protein levels (5.0% [0.2, 10.2] per unit UBF), and the rate of increase in total RNA levels predicted hypertrophy (0.3 mm [0.1, 0.4] per %‐point increase in total RNA per session). After de‐training, total RNA decreased (−19.3% [−29.0, −8.1]) without muscle mass changes indicating halted biosynthesis of ribosomes. Conclusion Ribosomes accumulate in the initial phase of resistance training with abundances sensitive to training cessation and associated with UBF protein levels. The average accumulation rate predicts muscle training‐induced hypertrophy.

Elevated muscle mass accompanied by transcriptional and nuclear alterations several months following cessation of resistance‐type training in rats

“…Increased total RNA was also suggestive of ribosomal biogenesis since the majority of total RNA (>85%) is ribosomal RNA (Figueiredo & McCarthy, 2019 ). Other shorter‐term studies regarding humans and rats have observed an increase in total RNA and ribosome biogenesis during multiple sessions of isometric muscle training (Hammarstrom et al, 2022 ; Kotani et al, 2019 ; Kotani et al, 2021 ). The total RNA data of the present study suggest that heightened transcriptional output and ribosomal content persist several months after resistance‐type training; and thereby provide an underlying rationale for the preservation of long‐term muscle mass.…”

“…Loading‐induced hypertrophy with transcriptional upregulation has been observed concomitant with nuclei accretion in various studies regarding both humans and rodents (Abou Sawan et al, 2021 ; Dungan et al, 2019 ; Goh et al, 2019 ; Hammarstrom et al, 2022 ; Lee et al, 2018 ; Mesquita et al, 2021 ; Murach et al, 2020 ). Bruusgaard et al in 2010 pioneered work utilizing a model of synergist ablation to cause hypertrophy followed by denervation‐induced atrophy to demonstrate that load‐induced gains in myonuclei could be long‐lasting after the termination of such exposure (Bruusgaard et al, 2010 ).…”

The accumulation rate of ribosomes predicts muscle training‐induced hypertrophy

“…3 In the current issue of Acta Physiologica, Hammarström, Øfsteng and colleagues from the Inland Norway University of Applied Sciences present very interesting new information about ribosome accumulation during the early phase of resistance training and how this impacts on muscle traininginduced hypertrophy. 4 They studied eleven men and women, 18-35 years of age, with a low previous history of resistance training. The subjects performed resistance training involving 12 sessions of resistance exercise (RE, 3-4 sessions per week) of unilateral knee extension with alternating legs.…”

“…Total RNA is considered to be a valid proxy marker of ribosomal density 3 . In the current issue of Acta Physiologica, Hammarström, Øfsteng and colleagues from the Inland Norway University of Applied Sciences present very interesting new information about ribosome accumulation during the early phase of resistance training and how this impacts on muscle training‐induced hypertrophy 4 . They studied eleven men and women, 18‐35 years of age, with a low previous history of resistance training.…”

Acute hypoxia attenuates resistance exercise‐induced ribosome signaling but does not impact satellite cell pool expansion in human skeletal muscle

“…21 The latter has emerged as a central regulator of load-induced ribosome biogenesis as UBF protein levels were strongly predictive of increases in total RNA in response to exercise training. 17 Activation of UBF by phosphorylation leads to the recruitment of transcription factor IA (TIF-1A) and selectivity factor 1 (SL1), which together forms the preinitiation complex required for activating the transcriptional machinery of Pol I. 22 Also, phosphorylation of TIF-1A at Ser 649 and Ser 633 promotes interaction with Pol I to induce pre-rRNA synthesis, 23,24 and is shown to increase robustly following an acute bout of resistance exercise.…”