title: Metabolic rate prediction by massless actigraphy for outdoor activities.
abstract: OBJECTIVE
  In military scenarios, there is a need for a system that can enable identification of possible future injury during different activities that are considered to be physically strenuous. The purpose of the present study was to determine whether the use of an octagonal actigraph in conjunction with heart rate (fc) measurements could serve as an accurate method for metabolic rate estimation for different free-living activities in field settings.
  
  
  METHODS
  Twenty young healthy volunteers (10 men, 22 +/- 3 years of age, and 10 women, 23 +/- 3 years of age) participated in this study. All participants were exposed to six different activities (walking, running, sweeping, climbing and descending stairs, and shopping). Continuous actigraphic measurements were collected from the hip and wrist, fc was monitored with a Polar chest belt, and oxygen consumption (VO2) was measured with a K4b2 system.
  
  
  RESULTS
  A prediction model for VO2 was constructed from actigraphic and fc measurements. Comparisons between predicted and measured VO2 values revealed high correlations (hip, R2 = 0.842; wrist, R2 = 0.822).
  
  
  CONCLUSIONS
  This new prediction model highly correlated with VO2 measurements. The hip was found to be more favorable than the wrist for assessment of VO2 for different free-living activities.
authors.affiliation: Institute of Military Physiology, Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Berlin
authors.forename: Liron
authors.initials: L
authors.lastname: Shalit
authors.forename: Yoni
authors.initials: Y
authors.lastname: Yarom
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Moran
mesh_terms: D056044:Actigraphy; D006801:Humans; D009043:Motor Activity; D010101:Oxygen Consumption; D012420:Running; D016138:Walking