PNF and Movement 2022; 20(1): 59-66
Relationship between 3D Ground Reaction Force and Leg Length Discrepancy during Gait among Standing Workers
Yong-Wook Kim, P.T., Ph.D.
Department of Physical Therapy, College of Medical Sciences, Jeonju University
Correspondence to: Yong-Wook Kim (
Received: January 20, 2022; Revised: February 11, 2022; Accepted: February 17, 2022; Published online: April 30, 2022.
© Korea Proprioceptive Neuromuscular Facilitation Association. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Purpose: The aim of this research was to verify the relationship between three-dimensional (3D) ground reaction force (GRF) and severity of leg length discrepancy (LLD) while walking at a normal speed. It used a 3D motion analysis system with force platforms in standing workers with LLD.
Methods: Subjects comprising 45 standing workers with LLD were selected. Two force platforms were used to acquire 3D GRF data based on a motion analysis system during gait. Vicon Nexus and Visual3D v6 Professional software were used to analyze kinetic GRF data. The subjects were asked to walk on a walkway with 40 infrared reflective markers attached to their lower extremities to collect 3D GRF data.
Results: The results indicated the maximal force in the posterior and lateral direction of the long limb occurring in the early stance phase during gait had significant positive correlation with LLD severity (r = 0.664∼0.738, p <0.01). In addition, the maximal force medial direction of the long limb occurring in the late stance phase showed a highly positive correlation with the LLD measurement (r = 0.527, p <0.01).
Conclusion: Our results indicate that greater measured LLD severity results in more plantar pressure occurring in the foot area during heel contact to loading response of the stance phase and the stance push-off period during gait.
Keywords: Ground reaction force, Leg length discrepancy, Standing worker

This Article