Research
Hormonal
Satellite cell fusion and the addition of new myonuclei are essential for muscle growth during early postnatal development but are not required for hypertrophy in adult skeletal muscle induced by most stimuli (e.g., reloading, androgens).
In adults, you can build muscle through increased protein synthesis without necessarily adding new nuclei (satellite cell fusion), especially with gradual training. Satellite cell fusion is more critical during development or after significant muscle damage.
GoodQualifiesHIGH confidence
Proliferation and fusion of satellite cells, leading to an increase in the number of myonuclei, may also contribute to muscle growth during early but not late stages of postnatal development and in some forms of muscle hypertrophy in the adult.
Why this rating
Supported by multiple genetic and ablation studies, though some controversy exists regarding specific hypertrophy models.
Source
Mechanisms regulating skeletal muscle growth and atrophy
Stefano Schiaffino et al. · FEBS Journal · 2013
DOI 10.1111/febs.12253
narrative_reviewCited 1,484×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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