title: Measuring perceived exercise capability and investigating its relationship with childhood obesity: a feasibility study.
abstract: OBJECTIVE
  According to the COM-B ('Capability', 'Opportunity', 'Motivation' and 'Behaviour') model of behaviour, three factors are essential for behaviour to occur: capability, opportunity and motivation. Obese children are less likely to feel capable of exercising. The implementation of a new methodological approach to investigate the relationship between perceived exercise capability (PEC) and childhood obesity was conducted, which involved creating a new instrument, and demonstrating how it can be used to measure obesity intervention outcomes.
  
  
  METHODS
  A questionnaire aiming to measure perceived exercise capability, opportunity and motivation was systematically constructed using the COM-B model and administered to 71 obese children (aged 9-17 years (12.24±0.2.01), body mass index (BMI) standard deviation scores (SDS) 2.80±0.660) at a weight-management camp in northern England. Scale validity and reliability was assessed. Relationships between PEC, as measured by the questionnaire, and BMI SDS were investigated for the children at the weight-management camp, and for 45 Spanish schoolchildren (aged 9-13 years, (10.52±1.23), BMI SDS 0.80±0.99). A pilot study, demonstrating how the questionnaire can be used to measure the effectiveness of an intervention aiming to bring about improved PEC for weight-management camp attendees, was conducted. No participants withdrew from these studies.
  
  
  RESULTS
  The questionnaire domain (exercise capability, opportunity and motivation) composite scales were found to have adequate internal consistency (a=0.712-0.796) and construct validity (χ(2)/degrees of freedom=1.55, root mean square error of approximation=0.072, comparative fit index=0.92). Linear regression revealed that low PEC was associated with higher baseline BMI SDS for both UK (b=-0.289, P=0.010) and Spanish (b=-0.446, P=0.047) participants. Pilot study findings provide preliminary evidence for PEC improvements through intervention being achievable, and measurable using the questionnaire.
  
  
  CONCLUSIONS
  Evidence is presented for reliability and validity of the questionnaire, and for feasibility of its use in the context of a childhood obesity intervention. Future research could investigate the link between PEC and childhood obesity further.
authors.affiliation: Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK.|Division of Medical Sciences and Graduate Entry Medicine, University of Nottingham, Nottingham, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Taylor
authors.affiliation: Department of Educational Sciences, University of La Rioja, Logroño, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Arriscado
authors.affiliation: Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: I
authors.initials: I
authors.lastname: Vlaev
authors.affiliation: Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Taylor
authors.affiliation: MoreLife, Leeds Metropolitan University, Leeds, UK.
authors.forename: P
authors.initials: P
authors.lastname: Gately
authors.affiliation: Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Darzi
mesh_terms: D000293:Adolescent; D002648:Child; D004739:England / Q000453:epidemiology; D015444:Exercise / Q000523:psychology*; D017079:Exercise Tolerance / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D009042:Motivation; D063766:Pediatric Obesity / Q000453:epidemiology / Q000517:prevention & control / Q000523:psychology*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012649:Self Concept; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires; D061217:Weight Reduction Programs