Why high-heel wearers hurt walking flat foot?

If you know of women who wear high-heels most of the time, you will notice that they often stand and walk tip-toe even when barefooted. This is because the women complain that it hurts to walk flat footed. This feeling of pain has been often theorized to be the result of a shrunken calf muscle. So Marco Narici from Manchester Metropolitan University, UK and Robert Csapo, from the University of Vienna, Austria sought to test the theory.

But what Csapo and Narici found was not shrunken calf muscles that causes pain when stretched. Using MRI scans, they found the volume of calf muscle between women who wore high-heel shoes were about the same as those of women who wore flat shoes. But what they did find was shorter muscles fibers in women who wore high-heels. About 13% shorter on average. While this would imply poor function, does it make it harder for the high-heeled women to walk flat footed? It didn't appear so.

Turning to the achilles tendon, the tendon attachment the calf muscles to the heel. What Csapo and Narici found were thicker and stiffer tendon in women who wore high-heels. While the tendon was not stretched longer than the other group, the thicker-stiffer tendon helped compensate for the shorter calf muscle.

It is this thicker and stiffer tendon that causes the discomfort when walking flat-footed as it cannot stretch enough.

References

Csapo, R., Maganaris, C. N., Seynnes, O. R. and Narici, M. V. (2010). On muscle, tendon and high heels. J. Exp. Biol. 213, 2582-2588.[Abstract/Full Text]