Load-induced human skeletal muscle hypertrophy: Mechanisms, myths, and misconceptions.
Level 5 - mechanism / opinion, no new human data
Narrative review evaluating mechanisms without systematic review methods or original data
PubMed 41276164 · doi:10.1016/j.jshs.2025.101104
What was done
The authors conducted a narrative review to evaluate the physiological mechanisms underlying load-induced skeletal muscle hypertrophy. They critically assessed the evidence for mechanical tension alongside popular concepts such as acute systemic hormonal spikes, metabolic stress, cell swelling ("the pump"), sarcoplasmic hypertrophy, and practical upper limits of muscle growth.
What was found
The abstract reports no numerical findings or effect sizes. The authors state that mechanical tension is the primary driver of hypertrophy, whereas acute systemic hormonal responses, metabolic stress, cell swelling, and distinct sarcoplasmic hypertrophy are not supported by strong scientific evidence as meaningful contributors.
Why it matters
This paper clarifies the physiological drivers of muscle growth, guiding coaches and trainees to prioritize mechanical tension rather than designing workouts around transient metabolic stress or hormonal spikes.
Limits
This is a narrative review rather than a systematic review or meta-analysis; no inclusion criteria, risk-of-bias evaluation, or primary study counts are provided in the abstract. No primary human outcome data or quantitative metrics are reported.