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Effects of external loads on balance control during upright stance: experimental results and model-based predictions.

Authors
Qu-X; Nussbaum-MA
Source
Gait Posture 2009 Jan; 29(1):23-30
NIOSHTIC No.
20034998
Abstract
The purpose of this study was to identify the effects of external loads on balance control during upright stance, and to examine the ability of a new balance control model to predict these effects. External loads were applied to 12 young, healthy participants, and effects on balance control were characterized by center-of-pressure (COP) based measures. Several loading conditions were studied, involving combinations of load mass (10% and 20% of individual body mass) and height (at or 15% of stature above the whole-body COM). A balance control model based on an optimal control strategy was used to predict COP time series. It was assumed that a given individual would adopt the same neural optimal control mechanisms, identified in a no-load condition, under diverse external loading conditions. With the application of external loads, COP mean velocity in the anterior-posterior direction and RMS distance in the medial-lateral direction increased 8.1% and 10.4%, respectively. Predicted COP mean velocity and RMS distance in the anterior-posterior direction also increased with external loading, by 11.1% and 2.9%, respectively. Both experimental COP data and model-based predictions provided the same general conclusion, that application of larger external loads and loads more superior to the whole body center of mass lead to less effective postural control and perhaps a greater risk of loss of balance or falls. Thus, it can be concluded that the assumption about consistency in control mechanisms was partially supported, and it is the mechanical changes induced by external loads that primarily affect balance control.
Keywords
Ergonomics; Musculoskeletal-system; Statistical-analysis; Biomechanical-modeling; Biomechanics; Posture; Author Keywords: Balance control; External loads; Model prediction; Center of pressure
Contact
Maury A. Nussbaum, Department of Industrial and Systems Engineering, Virginia Tech 250, Durham Hall (0118), Blacksburg, VA 24061
Publication Date
20090101
Document Type
Journal Article
Email Address
nussbaum@vt.edu
Funding Type
Grant
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-004089; Grant-Number-R01-OH-007882
ISSN
0966-6362
Source Name
Gait and Posture
State
VA
Performing Organization
Virginia Polytechnic Institute and State University
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