Bone Is Piezoelectric, Like A Gas Lighter

The bone in your thigh is not an inert beam. Load it - stand, step, jump - and a small voltage appears across it.

Two things produce that voltage. The collagen fibres that form bone's organic scaffold are piezoelectric: shear them and charge shifts across them. Yasuda reported it in dry bone in 1954, and Fukada and Yasuda confirmed it in 1957. In wet, living bone, though, the larger share comes from something else - fluid pushed through the bone's microscopic canals past charged walls, a streaming potential.

The collagen half is the same physics that makes the spark in a push-button lighter. The lighter uses a ceramic. Your skeleton uses a protein it built itself.

Whether these voltages help decide how bone rebuilds itself under load is still a hypothesis, not a settled fact.

Sources:
https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.705199/full
https://pmc.ncbi.nlm.nih.gov/articles/PMC9243952/
https://pmc.ncbi.nlm.nih.gov/articles/PMC5828134/
Original paper: E. Fukada and I. Yasuda, J. Phys. Soc. Jpn. 12, 1158 (1957)