Type of Document Master's Thesis Author Matrangola, Sara Louise Author's Email Address email@example.com 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
- balance recovery
Date of Defense 2008-07-15 Availability unrestricted AbstractObesity 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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