Stimuli and sensors that initiate skeletal muscle hypertrophy following resistance exercise.
Level 5 - mechanism / opinion, no new human data
Narrative review of mechanistic pathways without systematic search or original data
PubMed 30335577 · doi:10.1152/japplphysiol.00685.2018
What was done
This narrative review evaluated existing mechanistic literature regarding the initiating triggers ("hypertrophy stimuli") and upstream sensing mechanisms ("hypertrophy sensors") that drive resistance exercise-induced skeletal muscle hypertrophy. The authors synthesized candidate mechanisms across mechanical stimuli (including filamin-C-BAG3 signaling, nuclear deformation, and costameres), exercise-induced muscle damage, and metabolic stress-associated triggers.
What was found
The abstract reports no numerical data or effect sizes. Mechanical tension was identified as the primary candidate stimulus for muscle hypertrophy, with filamin-C-BAG3-dependent regulation of mTORC1, Hippo, and autophagy signaling highlighted as a plausible, though incompletely characterized, sensor alongside costameres and nuclear deformation. Exercise-induced muscle damage was evaluated as likely not essential for hypertrophy, and metabolic stress candidates were noted to rest on indirect evidence from blood flow restriction protocols with poorly characterized specific metabolites.
Why it matters
This review distinguishes primary upstream mechanical triggers and sensors from downstream signaling and secondary factors, providing a conceptual framework for how muscle tissue senses and converts loading into hypertrophy.
Limits
As a narrative review, it presents theoretical and mechanistic synthesis rather than original human trial data or a systematic search. Most discussed sensors and metabolites remain incompletely characterized and rely on indirect evidence.
Cited by
- supports Muscle hypertrophy and strength adaptations from resistance training are driven primarily by molecular signaling rather than actual muscle tissue breakdown or microtears.