High frequency components of bone strain in dogs measured during various activities.

Rubin et al. [J. Biomechanics 23, 43-54 (1990)] proposed that high frequency bone strains in the 15-30 Hz range might have significant influence on the morphological adaptation of bone tissue. We sought to further their findings by determining the magnitude of high frequency strains during various activities. We measured strains in the forelimbs of dogs during walking, standing and with their limbs unweighted. As negative controls, we measured strains while the dogs were tranquilized and after sacrifice. Strains in the 15-30 Hz range were not significantly greater than controls for any activity except walking, in which they were less than 4% as large as in the 0-15 Hz range. The high frequency strains observed during walking seemed to occur prior to footfall, suggesting that they were not the result of foot strike. The biological significance of high frequency bone strains has yet to be determined, but may be less than originally proposed because of the relatively small magnitude of these strains.