Microstrain
Also called: µε, microstrain units
What it means
Microstrain (µε) is a tiny measure of how much bone bends under force — one millionth of its original length.
Understanding microstrain helps explain why some types of movement give your bones more of a reason to adapt than others.
Microstrain, often written as µε, is simply a way to measure how much bone bends or deforms under force. One microstrain equals one millionth of the original length of the bone — far too small to see, but very real at the cellular level. When force passes through bone, this tiny deformation squeezes fluid-filled channels, presses on cell membranes, and creates movement of fluid around bone cells.
This matters because bone cells sense that fluid movement and shear, not the force itself. The bending acts like a signal, nudging the bone's internal cells to notice the load and respond. Researchers have measured these tiny strains during real activities, like walking, to understand what everyday movement actually does to bone tissue.
Scientists have also studied how much strain seems linked to bone forming new tissue, as part of a broader idea about how bone adapts to the loads placed on it. Everyday movement like walking produces relatively low strain in the shinbone, generally at or below the level associated with building new bone, though this can vary depending on how strong or weak someone's bone already is.
How sure is this?
Graded Established Science: Supported by broad scientific consensus and decades of research. 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.
Questions people ask about this
Walking is a familiar, repetitive movement, and your skeleton has adapted to it long ago. Because the forces involved are ones your bones already handle hundreds of times a day, your body treats walking as "maintenance" activity rather than a signal to build new bone. To trigger new bone formation, loading generally needs to be higher in magnitude, applied quickly, come from an unusual direction, and be brief with rest in between.
Read the full answer →Related words
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