Microdamage in bone can be caused by the various loads to which bones are subjected during normal daily activity. It occurs in two different types mainly depending on the load: diffuse damage and microcracks.
References
edit- Burr, D.B.; Allen, M.R. (2013). Basic and Applied Bone Biology. Elsevier Science. pp. 23–24. ISBN 978-0-12-391459-0.