title: Heart rate monitoring as a measure of physical activity in children.
abstract: OBJECTIVE
  Using a larger sample and broader range of activities than most previous investigations of HR monitoring, this study examined the need for individual calibration of the HR-VO2 prediction equation, the effect of including low-intensity activities when establishing the HR-VO2 equation, comparisons of different methods for calculating HR-VO2 prediction equations for maximum energy expenditure (EE) variance, and the effect of these different methods when applied to free-living HR data.
  
  
  METHODS
  Forty-three children ages 8 to 12 completed laboratory assessments of the relationship between HR and VO2. Different methods of estimating daily EE were applied to free-living HR data collected from 37 of these children.
  
  
  RESULTS
  There was significant individual variation in the HR-VO2 prediction equations. HR monitoring predicted VO2 during low-intensity activities, below most established cut points. Individual differences persisted during both high- and low-intensity activities. Although a HR-VO2 prediction equation generated from the group accounted for 85% of the variance in EE, significant improvements in prediction were achieved with individualized HR-VO2 prediction equations that took into account low-intensity activity levels.
  
  
  CONCLUSIONS
  Generic equations derived from group data may be suitable for some applications. However, for investigators requiring more precision, individual HR-VO2 equations significantly improve prediction.
authors.affiliation: National Institute of Child Health and Human Development, Bethesda, MD 20892-7510, USA. iannottr@mail.nih.gov
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Iannotti
authors.forename: Randal P
authors.initials: RP
authors.lastname: Claytor
authors.forename: Thelma S
authors.initials: TS
authors.lastname: Horn
authors.forename: Rusan
authors.initials: R
authors.lastname: Chen
mesh_terms: D002648:Child; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D009043:Motor Activity / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D012016:Reference Values