Title page for ETD etd-07162008-101646


Type of Document Master's Thesis
Author Matrangola, Sara Louise
Author's Email Address smatrang@vt.edu
URN etd-07162008-101646
Title A Modeling Investigation of Obesity and Balance Recovery
Degree Master of Science
Department Biomedical Engineering
Advisory Committee
Advisor Name Title
Madigan, Michael L. Committee Chair
Davy, Kevin P. Committee Member
Nussbaum, Maury A. Committee Member
Keywords
  • modeling
  • obesity
  • balance recovery
Date of Defense 2008-07-15
Availability unrestricted
Abstract
Obesity is associated with an increased risk of falls and subsequent injury. Previous studies have

shown weight loss and strength training to be beneficial to balance, but knowing which is more

beneficial will allow researchers to design interventions to maximize the benefits in terms of

balance and reducing risk of falls. Therefore, the purpose of the first study was to evaluate the

effects of weight loss and strength training on balance recovery using a combination of

laboratory experiments and mathematical modeling. Nine male subjects with BMI 30.1 to 36.9

kg/m2 were released from a forward lean and attempted to recover balance using an ankle

strategy. Lean angle was increased until subjects required a step or hip flexion to recover

balance. The maximum lean angle, θmax, was used as the measure of balance recovery capability.

Experimental data were used as inputs to an inverted pendulum model of balance recovery.

Multiple simulations were used to determine the effects of strength (maximum ankle torque and

ankle torque generation rate) and weight loss on θmax. Changes in weight and strength were

linearly related to changes in θmax. A 6.6 ± 0.4% decrease in weight or 6.9 ± 0.9% increase in

strength were estimated as required to improve (increase) θmax by 1 degree. Based on these

results, balance recovery using an ankle strategy can improve with either reductions in weight or

increases in strength. In addition, weight loss may be a more effective intervention than strength

gain at improving balance recovery capability. The purpose of the second study was to quantify

changes in body segment inertial parameters (BSIPs) with weight loss. These data were needed

to alter BSIPs in the first study to mimic changes with weight loss. Both before and after weight loss, magnetic resonance imaging scans were acquired along the length of the body and were used to calculate segment masses, COM positions, and radii of gyration. A number of significant changes in BSIPs occurred with weight loss.

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