Accuracy of classifying the movement strategy in the functional reach test using a markerless motion capture system

Abstract

The purpose of this study was to examine the accuracy of classifying the movement strategy in the functional reach test (FRT) using a markerless motion capture system (MLS) on the basis of values acquired with a marker-based motion capture system (MBS). Sixty young, injury-free individuals participated in this study. The task action involved reaching forward in the standing position. Using the Microsoft Kinect v2 as an MLS and Vicon as a MBS, the coordinates of the hip joints, knee joints and ankle joints were measured. The hip and ankle joint angles during the task were calculated from the coordinate data. These angles between MLS and MBS were compared using a paired t-test. The accuracy of movement strategy defined using MLS was examined based on the MBS. A t-test showed a significant difference in both the hip and ankle joint angles between systems (p < .01). However, in case of using data of left ankle joint, indices of the classification accuracy of MLS were 0.825 for sensitivity, 1.000 for specificity, infinity for positive likelihood ratio and 0.175 for negative likelihood ratio. The results for the right joint angle were similar to those of the left joint angle. Although the absolute measures in the hip and joint angles obtained using MLS differ from MBS, the MLS may be useful for accurately classifying the movement strategy adopted in the FRT.

Keywords:

• Postural balance
• range of motion
• articular
• data accuracy
• accidental falls
• movement

Acknowledgements

The authors thank Mr. Toshihide Okamoto, Mr. Ariaki Higashi, Ms. Noriko Nakashima and Mr. Hiromichi Kawanishi of System Friend Inc. for their technical help. The authors thank Mr. Takuya Tamura, Mr. Takuya Kubota, Mr. Daisuke Kuwahara, Mr. Kosuke Miyazaki, Ms. Haruka Takimoto, Mr. Haruka Shiraishi, Mr. Tomoki Takeda, Mr. Yoshiki Ishii, and Mr. Shochi Saito of the Department of Rehabilitation, and faculty of the Department of Rehabilitation, Hiroshima International University, for the data collecting.

Disclosure statement

Mr. Alejandro Diez is an employee of System Friend Inc.

Additional information

Funding

This research was sponsored by System Firnd Inc.