Age-related changes in standing ability on a foam surface based on the center-of-mass acceleration of each body segment

[Purpose] The purpose of this study was to elucidate the age-related changes in the stability of the quiet standing posture based on the acceleration of the center of mass of each body segment under deteriorated somatosensory conditions. [Participants and Methods] The participants in this study were 18 healthy elderly persons and 11 healthy young adults. A foam surface was placed on the force plate for load-bearing onto the somatosensory system. The participants maintained a quiet position on the force plate under two conditions: a firm surface and a foam surface. The accelerations of the head, thorax, pelvis, and whole body center of mass when quiet standing in two conditions were measured by a motion capture system. In the statistical analysis, regarding the center of mass of each body segment, the interactions were examined by performing a two-way analysis of variance using age and surface condition as factors. [Results] A two-way analysis of variance detected an interaction between age and surface factors for anteroposterior acceleration at the center of mass of the head. For other body segments, interactions between the two factors were not detected. [Conclusion] The results of anteroposterior acceleration at the center of mass of the head suggest that under conditions of deteriorated somatosensory function in the lower limbs, minute anteroposterior position adjustment of the head is an essential characteristic of the standing posture control mechanism in the elderly.