title: Oxygen Costs of the Incremental Shuttle Walk Test in Cardiac Rehabilitation Participants: An Historical and Contemporary Analysis.
abstract: BACKGROUND
  The incremental shuttle walk test (ISWT) is a standardised assessment for cardiac rehabilitation. Three studies have reported oxygen costs (VO2)/metabolic equivalents (METs) of the ISWT. In spite of classic representations from these studies graphically showing curvilinear VO2responses to incremented walking speeds, linear regression techniques (also used by the American College of Sports Medicine [ACSM]) have been used to estimate VO2.
  
  
  OBJECTIVE
  The two main aims of this study were to (i) resolve currently reported discrepancies in the ISWT VO2-walking speed relationship, and (ii) derive an appropriate VO2versus walking speed regression equation.
  
  
  METHODS
  VO2was measured continuously during an ISWT in 32 coronary heart disease [cardiac] rehabilitation (CHD-CR) participants and 30 age-matched controls.
  
  
  RESULTS
  Both CHD-CR and control group VO2responses were curvilinear in nature. For CHD-CR VO2= 4.4e0.23 × walkingspeed (km/h). The integrated area under the curve (iAUC) VO2across nine ISWT stages was greater in the CHD-CR group versus the control group (p < 0.001): CHD-CR = 423 (±86) ml·kg-1·min-1·km·h-1; control = 316 (±52) ml·kg-1·min-1·km·h-1.
  
  
  CONCLUSIONS
  CHD-CR group vs. control VO2was up to 30 % greater at higher ISWT stages. The curvilinear nature of VO2responses during the ISWT concur with classic studies reported over 100 years. VO2estimates for walking using linear regression models (including the ACSM) clearly underestimate values in healthy and CHD-CR participants, and this study provides a resolution to this when the ISWT is used for CHD-CR populations.
authors.affiliation: Institute of Medicine, University Centre Shrewsbury/University of Chester, The Guildhall, Frankwell Quay, Shrewsbury, UK. j.buckley@chester.ac.uk.
authors.forename: John P
authors.initials: JP
authors.lastname: Buckley
authors.affiliation: Centre for Sports and Exercise Sciences, School of Biological Sciences, University of Essex, Colchester, UK.
authors.forename: Fernando M F
authors.initials: FMF
authors.lastname: Cardoso
authors.affiliation: Department of Sport, Health and Exercise Science, University of Hull, Cottingham Road, Kingston Upon Hull, UK.
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Birkett
authors.affiliation: Centre for Sports and Exercise Sciences, School of Biological Sciences, University of Essex, Colchester, UK.
authors.forename: Gavin R H
authors.initials: GRH
authors.lastname: Sandercock
mesh_terms: D000072038:Cardiac Rehabilitation / Q000191:economics; D005080:Exercise Test; D006331:Heart Diseases / Q000503:physiopathology* / Q000534:rehabilitation; D006801:Humans; D010100:Oxygen / Q000191:economics*; D010101:Oxygen Consumption / Q000502:physiology*; D000070857:Walk Test / Q000379:methods*; D016138:Walking / Q000502:physiology*
chemical_list: D010100:Oxygen