Use of Strain Gauges in the Study of Primate Locomotor Biomechanics

Abstract

The strain gauge technique is a relatively recent addition to the catalogue of experimental methods available for functional analyses, especially locomotor studies. Strain gauges track the deformation of objects they are attached to, thus allowing the reconstruction of external forces and loads that cause these deformations. They are restricted to surface use, but extrapolations allow us to reconstruct strain patterns through the object (e.g., Gross et al., 1992; see also example in Figure 8). In the field of biomechanics there are two major applications: the measurement of bone deformations and the instrumentation of force measuring devices. The data in both fields can be used in interpreting musculoskeletal morphology. Functional interpretations of bony morphology have been historically based on correlations between shape and activity. The interface is the mechanical environment into which behaviors translate and in which bone develops, maintains and/or changes its shape. The mechanical demands of particular locomotor modes are commonly derived from behavioral observations in combination with biomechanical models. Measuring the external forces acting on limbs with force transducers is a first step in testing the numerous assumptions inherent in this process. Even with this background information, however, actual loadings of a bone can only be deduced with a certain degree of plausibility. In vivo measurement of bone strain is currently the only method of directly determining the major loading regimes caused by the external forces acting on the bone.