Energetic optimization during over-ground walking in people with and without Down syndrome

Stamatis Agiovlasitis, Robert W. Motl, Sushant M. Ranadive, Christopher A. Fahs, Huimin Yan, George H. Echols, Lindy Rossow, Bo Fernhall

Research output: Contribution to journalArticlepeer-review


Individuals with Down syndrome (DS) show reduced gait stability that may increase the metabolic rate (MR) during over-ground walking and alter their energetic cost per unit distance (EC transport) to speed relationship. If so, the preferred walking speed (PWS) of people with DS may coincide with their speed at minimal EC transport, reflecting energetic optimization. This study therefore examined whether MR and EC transport during over-ground walking differ between individuals with and without DS and whether PWS minimizes their EC transport. Expired gases were collected from 18 individuals with DS and 18 without during six over-ground walking trials, each lasting 6min, at PWS and at 0.51, 0.76, 1.01, 1.26, and 1.51m/s. Gross- and net-MR, and gross- and net-EC transport were expressed in dimensionless form. Energetically optimal walking speeds and minimal gross- and net-EC transport were determined from the gross- and net-EC transport to speed curves for each participant. Individuals with DS showed higher gross-MR, net-MR, gross-EC transport, and net-EC transport. PWS minimized gross-EC transport in participants with DS, but not in those without. PWS did not minimize net-EC transport in either group. Therefore, gross-EC transport minimization during over-ground walking may determine PWS when impairments alter the gross-EC transport to speed relationship.

Original languageEnglish (US)
Pages (from-to)630-634
Number of pages5
JournalGait and Posture
Issue number4
StatePublished - Apr 2011


  • Down syndrome
  • Economy
  • Gait
  • Impairment
  • Optimization

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Rehabilitation


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