title: Development of the physical activity index as a measure of total activity load and total kilocalorie expenditure during submaximal walking.
abstract: BACKGROUND
  Pedometers are most accurate at measuring steps, less accurate at estimating distance, and even less accurate at estimating kilocalorie expenditure. The purpose of this investigation was to create a Physical Activity Index (PAI) using pedometer step counts and rating of perceived exertion (RPE) to enhance the ability to estimate kilocalorie expenditure during walking exercise.
  
  
  METHODS
  Thirty-two females performed 3 counterbalanced walking bouts. During each bout, oxygen consumption, RPE, and step counts were measured. The PAI was calculated as the product of RPE and step count for each of the bouts.
  
  
  RESULTS
  Concurrent validation of the PAI was established using VO2 as the criterion variable. A multiple regression analysis revealed a strong, positive relation between PAI score and VO2 (r=.91). Data were then used to develop a statistical model to estimate kcal expenditure using the PAI score as the predictor variable.
  
  
  CONCLUSIONS
  The PAI was found to be an accurate method of estimating kcal expenditure and is a simple, unobtrusive and inexpensive tool which may be used in public health settings.
authors.affiliation: Department of Exercise and Rehabilitative Sciences, Slippery Rock University, Slippery Rock, PA, USA.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Smith
authors.forename: Michael
authors.initials: M
authors.lastname: Gallagher
authors.forename: Anne E
authors.initials: AE
authors.lastname: Hays
authors.forename: Fredric L
authors.initials: FL
authors.lastname: Goss
authors.forename: Robert
authors.initials: R
authors.lastname: Robertson
mesh_terms: D000293:Adolescent; D000328:Adult; D001837:Body Weights and Measures; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D009043:Motor Activity / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D015203:Reproducibility of Results; D016138:Walking / Q000502:physiology*; D055815:Young Adult