Comparison of foot kinetics and kinematics during gait initiation between young and elderly participants

[Purpose] To investigate the differences in foot kinetics during gait initiation between young and elderly participants using a modified multi-segment foot model. [Participants and Methods] Twelve young (23.3 ± 2.4 years) and 12 elderly participants (73.3 ± 3.9 years) were included in this study. Gait initiation was measured using a three-dimensional motion analysis system. We calculated the kinetic and kinematic values using our modified multi-segment foot model and compared those values with the values calculated using Bruening et al.'s multi-segment foot model. Modified gait initiation values were also compared between the elderly and young participants. [Results] Our modified multi-segment foot model, created using the Software for Interactive Musculoskeletal Modeling, showed similar values to those reported by Bruening et al. When we compared gait initiation between the elderly participants and their younger counterparts, the elderly exhibited lower torque and power values in the ankle, tarsometatarsal, and metatarsophalangeal joints. Additionally, the elderly exhibited a lower torque ratio in the distal joint than in the proximal joint (torque ratio: ankle joint >tarsometatarsal joint >metatarsophalangeal joint). [Conclusion] The elderly participants had less speed, stride, foot joint movement, moment, and power than the young participants. Moreover, the ratio of joint moment was smaller in the elderly participants. In elderly patients whose walking speed has decreased, consideration of the kinetics of the foot is important when deciding physiotherapy intervention.