Exercise and sport science

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Stamatis Agiovlasitis for the degree of Doctor of Philosophy in Exercise and Sport Science presented on August 15, 2007. Title: Three-dimensional Motion of the Center of Mass and Energetic Cost Across a Variety of Walking Speeds: A Comparison Between Adults With and Without Down Syndrome.

Abstract approved:____________________________________________________________

_________ Jeffrey A. McCubbin

It has been previously suggested that the walking pattern of individuals with Down syndrome is inefficient. This is thought to result from increased instability, particularly in the medio-lateral direction, due to the characteristic joint laxity and muscle hypotonia of individuals with DS. Therefore, this work was an attempt to gaininsight into the efficiency of gait in adults with DS by studying their mechanical and metabolic characteristics during treadmill walking. The first study examined the threedimensional motion of the center of mass (COM) and the spatio-temporal characteristics of adults with and without DS at a variety of walking speeds. Fifteen adults with DS and 15 adults without DS walked on a treadmill at sixand seven randomly presented dimensionless speeds (Froude numbers), respectively, during which kinematic data were collected. The range of medio-lateral COM position was greater in participants with DS, but the ranges of vertical COM position and anteriorposterior COM velocity did not differ between the groups. Participants with DS walked with faster steps across all speeds. Their step lengthwas shorter only during

slow walking and their step width did not differ from adults without DS. Participants with DS were more variable in medio-lateral and vertical COM position, anteriorposterior COM velocity, and in all spatio-temporal parameters than their controls. The second study examined whether the net VO2 and the net VO2 per unit distance across the same walking speeds aredifferent between adults with and without DS. The study also examined the relationship between the energetically optimal walking speed (EOWS) and the preferred walking speed (PWS) in both populations. Respiratory gases were collected from 14 adults with DS and 15 adults without DS as they walked at the same Froude numbers as for the first study. Adults with DS showed a higher net VO2 and net VO2per unit distance, and a slower EOWS compared to adults without DS. The PWS was the same for both groups and did not appear to minimize the net VO2 per unit distance in adults with DS. It was collectively concluded that the gait of adults with DS possesses several characteristics of inefficiency and has increased energetic requirements. Adults with DS do not prefer to walk at speeds thatminimize the metabolic demand.

©Copyright by Stamatis Agiovlasitis August 15, 2007 All Rights Reserved

Three-dimensional Motion of the Center of Mass and Energetic Cost Across a Variety of Walking Speeds: A Comparison Between Adults With and Without Down Syndrome

by Stamatis Agiovlasitis

A DISSERTATION submitted to Oregon State University

in partial fulfillment of therequirements for the degree of Doctor of Philosophy

Presented August 15, 2007 Commencement June 2008

Doctor of Philosophy dissertation of Stamatis Agiovlasitis presented on August 15, 2007.



_________ Major Professor, representing Exercise and Sport Science____________________________________________________________

_________ Chair of the Department of Nutrition and Exercise Sciences


_________ Dean of the Graduate School

I understand that my dissertation will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my dissertation to any reader upon request....
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