Dynamic Stability and Propulsion During Gait of the Healthy Elderly and Young Subjects Using Three Dimensional Kinetic Data

Using 3D kinetic data, this study was undertaken to determine whether similar joint muscle power activities or mechanical energies are developed for dynamic stability and propulsion during the gait of healthy elderly and young individuals’ dynamic stability. Eighteen elderly (71±6.8 years) and 18 young (25±4.1 years) able-bodied male subjects walked along a 10 m walkway at a freely-chosen speed. Data acquisition was performed with a Motion Analysis system and with a three Optotrak position sensors while one AMTI force platform recorded ground reaction forces. Spatio-temporal parameters as well as 22 peak joint muscle powers and their corresponding mechanical energies were calculated for each gait cycle. T-tests for independent samples was applied to determine statistical differences between the two groups (p<0.05). Though similar power patterns were observed for both groups, significant differences were noted for the peak joint muscle powers and their associated energies developed in most of the phases. In both groups, the greatest total work (positive and negative) was done at the hip, followed by the ankle and the knee, while the smallest and greatest differences between total energy in the elderly and young subjects were noted at the knee (58%) and ankle (36%), respectively. The hip extensors compensated for the hip abductors to maintain balance in elderly gait. For the younger subjects, propulsion from the hip extensors was initiated shortly after heel-strike, maintained throughout midstance and completed at push-off by the ankle and the hip for pull-off. In elderly gait, propulsion was limited to the ankle push-off and hip pull-off in the sagittal plane.