Modulation of sagittal-plane center of pressure and force vector direction in human standing on sloped surfaces

Aviroop Dutt-Mazumder; Kreg G Gruben

doi:10.1016/j.jbiomech.2021.110288

Modulation of sagittal-plane center of pressure and force vector direction in human standing on sloped surfaces

J Biomech. 2021 Apr 15:119:110288. doi: 10.1016/j.jbiomech.2021.110288. Epub 2021 Feb 16.

Authors

Aviroop Dutt-Mazumder¹, Kreg G Gruben²

Affiliations

¹ Customer Intelligence Analytics, Consumers Energy, Jackson, MI 49201, USA; Department of Physical Medicine & Rehabilitation, University of Michigan, Ann Arbor, MI 48105, USA. Electronic address: Aviroop.DuttMazumder1@cmsenergy.com.
² Department of Kinesiology, University of Wisconsin, USA; Department of Biomedical Engineering, University of Wisconsin, USA; Department of Mechanical Engineering, University of Wisconsin, Madison, WI 53706, USA.

PMID: 33636461
DOI: 10.1016/j.jbiomech.2021.110288

Abstract

The multi-joint coordination responsible for maintaining upright posture in the standing human manifests in the pattern of variation of the support-surface force (F). Assessment of both the translational and rotational kinematics in the sagittal-plane requires understanding the critical relationship between the direction and location of F. Prior work demonstrated that band-pass filtered F direction and center-of-pressure (CoP) covary in time such that the F vector lines-of-action pass near a fixed point called an intersection point (IP). The height of that IP (IP_z) varies systematically with the frequency of the pass band. From F measurements in able-bodied humans (n = 17) standing on various pitched surfaces, the present study also found the emergent property of an IP, with IP_z located above the center of mass (CoM) at frequencies <1.75 Hz and below the CoM for higher frequencies. This property aids in maintaining upright posture for various perturbation modes within a single control structure. From purely mechanical effects, standing on a pitched surface should not change IP_z, however these measurements of F show that IP_z is generally closer to CoM height. This characterization of quiet standing provides simple means of assessing the complex multi-joint coordination of standing and relates directly to the physical demands of controlling the translational and rotational aspects of body posture.

Keywords: Balance; Ground reaction force; Intersection point; Posture.

MeSH terms

Biomechanical Phenomena
Humans
Mechanical Phenomena
Postural Balance*
Posture
Standing Position*