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pISSN 2288-6982
eISSN 2288-7105

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Phys. Ther. Korea 2020; 27(2): 155-161

Published online May 20, 2020

https://doi.org/10.12674/ptk.2020.27.2.155

© Korean Research Society of Physical Therapy

Effect on the Limit of Stability of the Lowered Center of Mass With a Weight Belt

Jimmy Phan1, DPT, Kaylen Wakumoto1, DPT, Jeffrey Chen1, DPT, Woochol Joseph Choi2 , PT, PhD

1Department of Physical Therapy, Chapman University, Irvine, CA, USA, 2Injury Prevention and Biomechanics Laboratory, Department of
Physical Therapy, Yonsei University, Wonju, Korea

Correspondence to: Woochol Joseph Choi
E-mail: wcjchoi@yonsei.ac.kr
https://orcid.org/0000-0002-6623-3806

Received: January 30, 2020; Revised: March 31, 2020; Accepted: April 24, 2020

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0)which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: The consequences of falls are often debilitating, and prevention is important. In theory, the lower the center of mass (COM), the greater postural stability during standing, and a weight belt at the waist level may help to lower the COM and improve the standing balance.
Objects: We examined how the limit of stability (LOS) was affected by the lowered center of mass with the weight belt.
Methods: Twenty healthy individuals participated in the LOS test. After calculating each participant’s COM, a weight belt was fastened ten centimeters below the COM. Trials were acquired with five weight belt conditions: 0%, 2%, 4%, 6%, and 8% of body weight. Outcome measures included reaction time, movement velocity, endpoint excursion, maximum excursion, and directional control in 4 cardinal moving directions.
Results: None of our outcome variables were associated with a weight belt (p > 0.075), but all of them were associated with moving direction (p < 0.01). On average, movement velocity of the COM and maximum excursion were 31% and 18% greater, respectively, in mediolateral than anteroposterior direction (5.4°/s vs. 4.1°/s; 97.5% vs. 82.6%).
Conclusion: Our results suggest that postural stability was not affected by the weightinduced lowered COM, informing the development and improvement of balance training strategies.

Keywords: Balance, Center of mass, Limit of stability, Weight belt