It is well established that bone is remodeled in response to loading patterns. The two most influential loads for limb bones are those incurred during locomotion and those due to body size. Whereas the impact of body size (weight) on limb bone morphology has been studied in a variety of animals, few studies have paired an analysis of forces generated during locomotion (kinetics) with an examination of bone structures associated with strength and rigidity under loading (structural mechanics). This study will analyze the kinetics of locomotion in rodents (guinea pigs, chinchillas, agoutis, pacas, and Patagonian hares), representing slow to fast running species and small (under 2 lbs.) to large (20 lbs.) body sizes. The animals will be allowed to run freely in an enclosure fitted with a force plate that will record the forces generated by the limbs during locomotion. Forelimb and hind limb forces and impulses in all five species will be tested for differences as a result of locomotor pattern, locomotor speed, and body size. The principal investigator has already completed a study of buttressing patterns in the long bone shafts of these rodents and will accordingly match kinetic data with structual data. The most significant consequence of the study, therefore, will be in forming a bridge between kinetic performance and observed anatomy which can then be used to understand the structural adaptations of any bone, including human.
