title: Energy expenditure estimates of the Caltrac accelerometer for running, race walking, and stepping.
abstract: OBJECTIVE
  To examine the accuracy of the Caltrac accelerometer for estimating energy expenditure (EE) during three exercise modes.
  
  
  METHODS
  A subset of 31 women (mean (SEM) age 22.6 (5) years) as selected from a training study comparing various physiological parameters during race walking, running, and stepping. Subjects each performed mode specific graded exercise tests to peak VO2. Regression equations for VO2 v heart rate (HR) were generated from each individual's test data. EE (kcal and kJ) was estimated for each VO2 value based on the respiratory exchange ratio, and kcal v HR regression equations were generated to predict EE from each subject's HR data (EE-HR). HR in the field was monitored by telemetry, and two Caltrac monitors, one set for EE and one to give counts, were attached to a belt over opposite hips.
  
  
  RESULTS
  EE-HR was not significantly different across exercise modes. Caltrac overestimated EE (P < 0.01) in runners (14%) and walkers (19%) but underestimated EE in steppers by about 10% (P = 0.12).
  
  
  CONCLUSIONS
  The Caltrac is a reliable instrument but it did not accurately distinguish EE in running, race walking, or stepping in a group of young women.
authors.affiliation: Department of Exercise Science and Physical Education, Arizona State University, Tempe 85287-0701, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Swan
authors.forename: W C
authors.initials: WC
authors.lastname: Byrnes
authors.forename: E M
authors.initials: EM
authors.lastname: Haymes
mesh_terms: D000054:Acceleration; D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D004867:Equipment Design; D005080:Exercise Test; D005260:Female; D005544:Forecasting; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012044:Regression Analysis; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology*; D012680:Sensitivity and Specificity; D013177:Sports / Q000502:physiology*; D013686:Telemetry / Q000295:instrumentation; D016138:Walking / Q000502:physiology*