title: Relationships between oxygen uptake, dynamic body acceleration and heart rate in humans.
abstract: OBJECTIVE
  Accurate estimation of energy expenditure (EE) is important in human and animal behavior analysis. Rate of oxygen consumption (VO2) reflects EE during aerobic metabolism but is not always convenient. Alternative methods include heart rate (HR) and overall dynamic body acceleration (ODBA). A favorable ODBA-VO2 relationship was recently reported but the strength of association between VO2, ODBA, HR and its variability (HRV) is less clear.
  
  
  METHODS
  Fifteen young (23±4 years) healthy males of similar aerobic fitness (maximal oxygen uptake, VO2max=49.7±8.5 mL·kg(-1)·min(-1)) carried out progressive maximal exercise. ODBA, HRV and V̇O2 were recorded continuously. Relationships between ODBA, HRV and V̇O2 were explored using regression methods.
  
  
  RESULTS
  VO2 was strongly related to ODBA and RR during walking (R=0.45,0.30; P<5x10(-5)) and running (R=0.60,0.38; P<5x10(-5)). HRV was related to VO2 during walking only (R=0.11-0.26; 0.005<P<5x10(-5)). A strong ODBA-RR relationship during walking (R=0.45; P<5x10(-5)) was diminished during running (R=0.25; P<5x10(-5)).
  
  
  CONCLUSIONS
  ODBA is a stronger proxy for EE than RR or HRV, especially during running gaits. HRV is weakly related to EE and cannot be recommended for its estimation. ODBA and RR are relatively easily measured but careful attention to gait is imperative as it changes these relationships markedly.
authors.affiliation: College of Engineering, Swansea University, Swansea, UK - m.j.lewis@swansea.ac.uk.
authors.forename: L A
authors.initials: LA
authors.lastname: D'silva
authors.forename: A
authors.initials: A
authors.lastname: Cardew
authors.forename: L
authors.initials: L
authors.lastname: Qasem
authors.forename: R P
authors.initials: RP
authors.lastname: Wilson
authors.forename: M J
authors.initials: MJ
authors.lastname: Lewis
mesh_terms: D000054:Acceleration; D000328:Adult; D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D011237:Predictive Value of Tests; D012044:Regression Analysis; D012420:Running / Q000502:physiology*; D016138:Walking / Q000502:physiology*
chemical_list: D010100:Oxygen