Muscles, exercise and obesity: skeletal muscle as a secretory organ.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic pathways without primary human data
PubMed 22473333 · doi:10.1038/nrendo.2012.49
What was done
Narrative review synthesizing findings on skeletal muscle as a secretory organ and detailing the biological roles of contraction-induced cytokines and peptides (myokines) on local and systemic physiology.
What was found
The abstract reports no quantitative values or statistical results. It summarizes qualitative signaling pathways: skeletal muscle secretes several hundred peptides; myostatin, LIF, IL-6, and IL-7 mediate muscle hypertrophy and myogenesis; BDNF and IL-6 regulate AMPK-mediated fat oxidation; IL-6 coordinates systemic actions on the liver, adipose tissue, immune system, and pancreas; IGF-1 and FGF-2 provide osteogenic regulation; FSTL-1 modulates endothelial function; and irisin induces brown-fat-like differentiation.
Why it matters
It provides a conceptual framework establishing skeletal muscle as an endocrine organ, explaining how physical inactivity alters inter-organ signaling to contribute to chronic disease.
Limits
As a narrative review, it presents no primary experimental data, structured systematic search methodology, or quantitative meta-analysis. Cited mechanisms primarily reflect preclinical or observational pathways.
Cited by
- supports Interleukin-6 released by exercising muscle is a key trigger for the activation of AMP kinase (AMPK).