Research
Hormonal
Skeletal muscle hypertrophy is primarily regulated by the balance between protein synthesis and degradation, driven by the IGF1-Akt-mTOR pathway (positive regulator) and the myostatin-Smad2/3 pathway (negative regulator).
To build muscle, you need to stimulate the IGF1-Akt-mTOR pathway (via resistance training and adequate protein) while minimizing the inhibitory effects of myostatin. It's not just about eating enough to 'stop' loss; active signaling drives the growth.
StrongSupportsVERY_HIGH confidence
Two major signaling pathways control protein synthesis, the IGF1–Akt–mTOR pathway, acting as a positive regulator, and the myostatin–Smad2/3 pathway, acting as a negative regulator...
Why this rating
Supported by extensive genetic gain/loss-of-function studies and transgenic models cited in the review.
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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