GLOSSARY

Evidence for muscle-derived signals

A candidate myokine requires evidence of muscle production and release. Endocrine action additionally requires biologically relevant delivery and a response at a distant target. Expression within muscle or an increase in blood alone does not establish this entire chain.

A distinction that matters

Human assay variability and source attribution complicate interpretation. Cell and animal findings do not by themselves establish a reliable blood target or a proven human performance intervention.

Interpreting exercise studies

Sampling time, muscle damage, other tissue sources and assay specificity affect measured exerkines. Animal or cell findings can identify mechanisms but do not guarantee a proven human performance benefit. Local action may be important even without a detectable circulating rise.