Validation of MET estimates and step measurement using the ActivPAL physical activity logger

Deirdre M. Harrington, Gregory J. Welk, Alan E. Donnelly

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)


The purpose of this study was to determine the validity of the metabolic equivalent (MET) equation and step rate function of the ActivPAL™ physical activity logger in a group of females. Using a standard treadmill protocol, 62 females aged 15-25 years walked on a treadmill at speeds between 3.2 and 7.0 km h-1 while wearing an ActivPAL. Oxygen consumption was measured using expired gas analysis at each speed and METs for each speed were estimated based on each participant's own resting metabolic rate. A sub-set of 18 participants also wore an Actigraph. Results showed that the in-built equation in the ActivPAL significantly underestimated (P < 0.001) METs under treadmill conditions at higher intensities. The ActivPAL equation is based on step rate yet the relationship between counts and measured METs (r = 0.76; P < 0.001) is stronger than that between steps and measured METs (r = 0.59; P < 0.001). Both the ActivPAL and Actigraph step functions showed no significant difference (P > 0.05) to video recorded step rate except at the slowest walking speed where the Actigraph significantly underestimated steps (P < 0.05). The development of a new equation based on the counts-METs relationship that includes a variety of speeds and activities would be useful. The ActivPAL step function performs better than the Actigraph at the slowest walking speed under treadmill conditions. 
Original languageEnglish
Pages (from-to)627-633
Number of pages7
JournalJ. Sports Sci.
Issue number6
Publication statusPublished - 24 Feb 2011


  • accelerometer
  • Activpal
  • mets
  • physical activity
  • actimetry
  • adolescent
  • adult
  • article
  • basal metabolic rate
  • calorimetry
  • energy metabolism
  • exercise
  • female
  • human
  • locomotion
  • metabolic equivalent
  • methodology
  • physiology
  • reproducibility
  • validation study
  • walking


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