Muscle Fiber Hypertrophy and Myonuclei Addition: A Systematic Review and Meta-analysis

Conceição, Miguel Soares; Vechin, Felipe Cassaro; Lixandrão, Manoel Emílio; Damas, Felipe; Libardi, Cleiton Augusto; Tricoli, Valmor; Roschel, Hamilton; Camera, Donny M.; Ugrinowitsch, Carlos

doi:10.1249/mss.0000000000001593

Cited by 55 publications

(57 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Numerous studies in humans and rodents report that satellite cell proliferation and myonuclear accretion occurs with skeletal muscle fiber hypertrophic growth (reviewed in Van der Meer et al, 2011a ; Murach et al, 2018a ). The often-observed incidence of large muscle fibers with a high proportion of myonuclei after training reinforces the notion that the myonuclear domain may expand modestly ( Conceicao et al, 2018 ), but generally remains stable during hypertrophy (Scenario A in Figure 1 ). Muscle fiber hypertrophy and myonuclear accretion via testosterone supplementation further implies that myonuclear accretion directly contributes to adult muscle growth ( Sinha-Hikim et al, 2003 ; Egner et al, 2013 ).…”

Section: Evidence For Myonuclear Domain Flexibility During Hypertrophsupporting

confidence: 69%

“… Herman-Montemayor et al (2015) reported Type 2 fiber hypertrophy > 30% with non-statistically significant myonuclear accretion (9.5%, P < 0.10) and a 29% expansion of the myonuclear domain after resistance training in untrained women. These findings do not necessarily rule out the existence of a “myonuclear domain ceiling”, but do challenge the idea of a muscle fiber growth “threshold” beyond which myonuclear accretion is theoretically required to sustain hypertrophy ( Kadi et al, 2004 ; Petrella et al, 2006 ; Conceicao et al, 2018 ). This threshold was derived most recently from correlations in human work and, while translational outcomes in humans are the ultimate goal, loss-of-function studies in mice are necessary to complement the indirect, correlative evidence gained in humans and to determine causality.…”

Section: Evidence For Myonuclear Domain Flexibility During Hypertrophmentioning

confidence: 78%

See 1 more Smart Citation

Myonuclear Domain Flexibility Challenges Rigid Assumptions on Satellite Cell Contribution to Skeletal Muscle Fiber Hypertrophy

et al. 2018

View full text Add to dashboard Cite

Satellite cell-mediated myonuclear accretion is thought to be required for skeletal muscle fiber hypertrophy, and even drive hypertrophy by preceding growth. Recent studies in humans and rodents provide evidence that challenge this axiom. Specifically, Type 2 muscle fibers reliably demonstrate a substantial capacity to hypertrophy in the absence of myonuclear accretion, challenging the notion of a tightly regulated myonuclear domain (i.e., area that each myonucleus transcriptionally governs). In fact, a “myonuclear domain ceiling”, or upper limit of transcriptional output per nucleus to support hypertrophy, has yet to be identified. Satellite cells respond to muscle damage, and also play an important role in extracellular matrix remodeling during loading-induced hypertrophy. We postulate that robust satellite cell activation and proliferation in response to mechanical loading is largely for these purposes. Future work will aim to elucidate the mechanisms by which Type 2 fibers can hypertrophy without additional myonuclei, the extent to which Type 1 fibers can grow without myonuclear accretion, and whether a true myonuclear domain ceiling exists.

show abstract

Section: Evidence For Myonuclear Domain Flexibility During Hypertrophsupporting

confidence: 69%

Section: Evidence For Myonuclear Domain Flexibility During Hypertrophmentioning

confidence: 78%

Myonuclear Domain Flexibility Challenges Rigid Assumptions on Satellite Cell Contribution to Skeletal Muscle Fiber Hypertrophy

et al. 2018

View full text Add to dashboard Cite

show abstract

“…This is remarkable given that even though SC fusion was higher in VResRun, we observed similar numbers of GFP positive MyHCI versus MyHCIIa bers in both VRun and VResrun. Thus, the lack of hypertrophy in the heavily SC fused MyHCI bers promotes the hypothesis that myonuclear accretion might also play a role in endurance adaptations to interval training [11,54] and that myonuclear accretion is not merely a way to withstand to expansion of the myonuclear domain [55].…”

Section: Discussionmentioning

confidence: 96%

Exercise promotes satellite cell contribution to myofibers in a load-dependent manner

Masschelein

D’Hulst

Zvick

et al. 2020

Preprint

View full text Add to dashboard Cite

Background Satellite cells (SCs) are required for muscle repair following injury and are involved in muscle remodeling upon muscular contractions. Exercise stimulates SC accumulation and myonuclear accretion. To what extent exercise training at different mechanical loads drive SC contribution to myonuclei however is unknown. Results By performing SC fate tracing experiments, we show that 8-weeks of voluntary wheel running increased SC contribution to myofibers in mouse plantar flexor muscles in a load-dependent but fiber type-independent manner. Increased SC fusion however was not exclusively linked to muscle hypertrophy as wheel running without external load substantially increased SC fusion in the absence of fiber hypertrophy. Due to nuclear propagation, nuclear fluorescent fate tracing mouse models were inadequate to quantify SC contribution to myonuclei. Ultimately, by performing fate tracing at the DNA level, we show that SC contribution mirrors myonuclear accretion during exercise. Conclusions Collectively, mechanical load during exercise independently promotes SC contribution to existing myofibers. Also, due to propagation of nuclear fluorescent reporter proteins, our data warrant caution for the use of exisiting reporter mouse models for the quantitative evaluation of satellite cell contribution to myonuclei.

show abstract

“…This is remarkable given that even though SC fusion was higher in VResRun, we observed similar numbers of GFP positive MyHCI versus MyHCIIa fibers in both VRun and VResrun. Thus, the lack of hypertrophy in the heavily SC fused MyHCI fibers promotes the hypothesis that myonuclear accretion might also play a role in endurance adaptations to interval training (Abreu et al, 2017;Hawley et al, 2014) and that myonuclear accretion is not merely a way to withstand to expansion of the myonuclear domain (Conceiçao et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Exercise promotes satellite cell contribution to myofibers in a load-dependent manner

Masschelein

D’Hulst

Zvick

et al. 2020

Preprint

View full text Add to dashboard Cite

Satellite cells (SCs) are required for muscle repair following injury and are involved in muscle remodeling upon muscular contractions. Exercise stimulates SC accumulation and myonuclear accretion. To what extent exercise training at different mechanical loads drive SC contribution to myonuclei however is unknown. By performing SC fate tracing experiments, we show that 8-weeks of voluntary wheel running increased SC contribution to myonuclei in mouse plantar flexor muscles in a load-dependent but fiber type-independent manner. Increased SC fusion however was not exclusively linked to muscle hypertrophy as wheel running without external load substantially increased SC fusion in the absence of fiber hypertrophy. Due to nuclear propagation, nuclear fluorescent fate tracing mouse models were inadequate to quantify SC contribution to myonuclei. Ultimately, by performing fate tracing at the DNA level, we show that SC contribution mirrors myonuclear accretion during exercise. Collectively, these findings provide direct evidence that mechanical load during exercise independently promotes SC contribution to existing myofibers.

show abstract

Muscle Fiber Hypertrophy and Myonuclei Addition: A Systematic Review and Meta-analysis

Abstract: Although a more consistent myonuclei addition occurs when muscle fiber hypertrophy is >22%, our results challenge the concept of a muscle hypertrophy threshold as significant myonuclei addition occurs with lower muscle hypertrophy (i.e., <10%).

Cited by 55 publications

References 39 publications

Myonuclear Domain Flexibility Challenges Rigid Assumptions on Satellite Cell Contribution to Skeletal Muscle Fiber Hypertrophy

Myonuclear Domain Flexibility Challenges Rigid Assumptions on Satellite Cell Contribution to Skeletal Muscle Fiber Hypertrophy

Exercise promotes satellite cell contribution to myofibers in a load-dependent manner

Exercise promotes satellite cell contribution to myofibers in a load-dependent manner

Contact Info

Product

Resources

About