title: Oxygen cost during treadmill walking with hip and knee immobilised.
abstract: The aim of this study was to determine the effect of immobilising the knee and hip on the oxygen cost (ml·kg(-1)·min(-1)) to velocity relationship during treadmill walking. The study was a prospective experimental conducted in a Rehabilitation centre. Ten healthy individuals, five men and five women, with no gait abnormality participated. Following familiarisation five men and five women walked on a treadmill and selected their own, free "comfortable walking velocity "(SSWS). Subjects then performed an incremental test at -60 to +60% of SSWS. Individuals later repeated the test with the knee and hip of one limb immobilised. Samples of expired air were measured at each velocity and the oxygen cost (ml·kg(-1)·min(-1)) to Froude number (Fr) relationship plotted (where calculation of Fr normalizes for subjects of differing leg length and acts as an index of velocity). There was a higher oxygen cost, and lower Fr at SSWS during immobilised (0.21 ± 0.03 ml·kg(-1)·min(-1); Fr = 0.12 ± 0. 03) compared with free walking (0.16 ± 0.02 ml·kg(-1)·min(-1); Fr = 0.18 ± 0.04) (p < 0. 01). Statistical analysis demonstrated that during immobilised walking an inverse fit (y = β0 + β1/x) and for free walking a cubic fit (y = β0 + β1x + β2x(2) + β3x(3) ) best fitted the data. Hip and knee immobilisation increased the oxygen cost at SSWS and altered the oxygen cost to Fr relationship. The results have implications in selecting optimal walking velocities in individuals with impairments affecting mobility such as hemiplegic gait. Key PointsWalking with one limb immobilised requires greater energy cost than normal free walking.This has clinical implications when developing rehabilitation strategies for patients who mobility problems such as those with hemi paretic gait.
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University , Headington, Oxford, UK ; Rivermead Research Group, Oxford Centre for Enablement, Nuffield Orthopaedic Centre, Headington, Oxford, UK ; General Practice and Primary Care, University of Birmingham , Edgbaston, Birmingham, UK.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Elsworth
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University , Headington, Oxford, UK ; Rivermead Research Group, Oxford Centre for Enablement, Nuffield Orthopaedic Centre, Headington, Oxford, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Dawes
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University , Headington, Oxford, UK ; Rivermead Research Group, Oxford Centre for Enablement, Nuffield Orthopaedic Centre, Headington, Oxford, UK.
authors.forename: Johnny
authors.initials: J
authors.lastname: Collett
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University , Headington, Oxford, UK.
authors.forename: Ken
authors.initials: K
authors.lastname: Howells
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University , Headington, Oxford, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Ramsbottom
authors.affiliation: Department of Mathematical Sciences, Oxford Brookes University , Wheatley Campus, Wheatley, Oxford UK.
authors.forename: Hooshang
authors.initials: H
authors.lastname: Izadi
authors.affiliation: General Practice and Primary Care, University of Birmingham , Edgbaston, Birmingham, UK.
authors.forename: Cath
authors.initials: C
authors.lastname: Sackley
keywords: Froude number; hemiplegic gait; hip; immobilisation; knee; oxygen cost; walking