title: Prediction of oxygen uptake during over-ground walking in people with and without Down syndrome.
abstract: The reduced gait stability and aerobic fitness of people with Down syndrome (DS) may increase their rate of gross oxygen uptake (gross-VO(2)) during over-ground walking. If so, the ACSM equation predicting gross-VO(2) from speed may not be appropriate and an equation specifically for these individuals may be needed. This study therefore examined whether the relationship between gross-VO(2) and speed differs between individuals with and without DS during over-ground walking and attempted to develop a gross-VO(2) prediction equation for people with DS. Gross-VO(2) was measured in 18 persons with DS (24.7 ± 6.8 years; 8 men) and 22 persons without DS (25.9 ± 4.8 years; 9 men) at rest and during five over-ground walking trials, each lasting 6 min, at 0.5, 0.75, 1.0, 1.25, and 1.5 m/s. Multi-level modeling with random intercepts and slopes demonstrated significant effects of speed, group, group-by-speed interaction, and speed squared (P < 0.001). In each group, actual gross-VO(2) did not differ from gross-VO(2) predicted by the regression equation across speeds. Bland-Altman plots showed somewhat greater variability in the difference between actual and predicted gross-VO(2) for participants with DS. Mean absolute error of prediction was 10.75 and 10.67% for participants with and without DS, respectively. In participants with DS, the ACSM formula under-estimated gross-VO(2) across speeds, whereas, in participants without DS, only at 1.5 m/s (P < 0.001). Therefore, individuals with DS show altered curvilinear gross-VO(2) to speed relationship during over-ground walking. The present regression equation appears to offer accurate prediction in people with DS and could be used for prescribing over-ground walking intensities.
authors.affiliation: Department of Kinesiology, Mississippi State University, 233 McCarthy Gym, P.O. Box 6186, Mississippi State, MS 39762, USA. sagiovlasitis@colled.msstate.edu
authors.forename: Stamatis
authors.initials: S
authors.lastname: Agiovlasitis
authors.forename: Robert W
authors.initials: RW
authors.lastname: Motl
authors.forename: Sushant M
authors.initials: SM
authors.lastname: Ranadive
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Fahs
authors.forename: Huimin
authors.initials: H
authors.lastname: Yan
authors.forename: George H
authors.initials: GH
authors.lastname: Echols
authors.forename: Lindy
authors.initials: L
authors.lastname: Rossow
authors.forename: Bo
authors.initials: B
authors.lastname: Fernhall
mesh_terms: D000054:Acceleration; D000328:Adult; D004314:Down Syndrome / Q000378:metabolism* / Q000503:physiopathology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D005544:Forecasting; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D013997:Time Factors; D016138:Walking / Q000502:physiology*; D055815:Young Adult