Impact of Joint Fixation on Postural Dynamics during Single-Leg Stance

Abstract

We investigated the relationship between the mechanical degrees of freedom (DoF) and its postural dynamics. The joint DoF was fixed to constrain the mechanical DoF. Nine participants were required to perform a single-leg stance task. The center of pressure trajectory data was analyzed. Ankle fixation induced a larger amount of variability in the anteroposterior direction, and less dimensionality and complexity in the mediolateral direction. These results suggest that the ankle joint fixation caused limited postural sway in the mediolateral direction; therefore, functional DoF and complexity decreased. In contrast, it increased the amount of postural sway variability in the anteroposterior direction. Our findings imply a direct relationship between the mechanical DoF of the human movement system and its postural dynamics.

Keywords:

• complexity
• correlation dimension
• degrees of freedom
• dimensionality
• sample entropy

Acknowledgments

This work was based on the previous presentation in the JSAI International Symposium on Artificial Intelligence 2018.

Authors’ Contributions

Conceptualization, data curation, formal analysis, funding acquisition, methodology, project administration, resources, software, visualization, roles/writing—original draft: KK; investigation, supervision, validation: KK, KY, HY; writing—review and editing: KK, KY, HY.

Consent to Participate

Each participant provided written informed consent for participation in this study.

Consent for Publication

Each participant provided informed consent for publication of this study.

Ethics Approval

Approved by the research ethics committee of Kanagawa University [No. 2021-35].

Disclosure Statement

The authors declare that they have no competing interests.

Data Availability Statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by the Kanagawa University Grant for Joint Research.