Irisin
What it means
Irisin is a chemical messenger (myokine) released by working muscles that signals bone-building cells to become active.
It's a reminder that keeping your muscles active is part of the chemical conversation that supports your bones, not just the mechanical loading.
Irisin is a myokine, a chemical messenger released by your muscles when they work. It travels to bone and signals bone-building cells to get active. This is one way your muscles and bones stay in conversation with each other, not just through the physical pulling and loading of movement, but through chemistry too.
Bone doesn't just receive messages, it sends them back. It releases osteocalcin, a hormone that helps muscle use energy. There's also myostatin, a different molecule that suppresses both muscle and bone activity at once. Together these signals explain why muscle and bone tend to rise and fall together over a lifetime.
This back-and-forth helps explain why age-related muscle loss (sarcopenia) and bone loss (osteoporosis) so often show up in the same person at the same time. Researchers increasingly see them as two expressions of one underlying process rather than separate problems, which is why keeping muscles working matters for bone health too.
How sure is this?
Graded Emerging Evidence: Promising research, but findings are still developing and may be primarily from laboratory or animal studies. Read each study with its grade in mind. One study is a piece of the picture, not the whole of it.
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Related words
Myokines are chemical messengers released by working muscle that can signal bone cells, linking muscle activity and…
Myostatin is a molecule made by muscle that slows down growth in both muscle and bone tissue.
Osteocalcin is a hormone made by bone that helps regulate blood sugar, muscle energy use, and other body functions…
Sarcopenia is the gradual loss of muscle mass and strength that comes with aging, and it's closely tied to bone health.
An osteoblast is a cell that builds new bone by laying down fresh bone matrix, working alongside cells that break…
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
