Validation of thigh-based accelerometer estimates of postural allocation in 5-12 year-olds

Christiana M.T. van Loo, Anthony D. Okely, Marijka J. Batterham, Trina Hinkley, Ulf Ekelund, Søren Brage, John J. Reilly, Rachel Jones, Xanne Janssen, Dylan P. Cliff

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Abstract

Objectives: To validate activPAL3TM (AP3) for classifying postural allocation, estimating time spent in postures and examining the number of breaks in sedentary behaviour (SB) in 5-12 year-olds. Design: Laboratory-based validation study. Methods: Fifty-seven children completed 15 sedentary, light- and moderate-to-vigorous intensity activities. Direct observation (DO) was used as the criterion measure. The accuracy of AP3 was examined using a confusion matrix, equivalence testing, Bland-Altman procedures and a paired t-test for 5-8y and 9-12y. Results: Sensitivity of AP3 was 86.8%, 82.5% and 85.3% for sitting/lying, standing, and stepping, respectively, in 5-8y and 95.3%, 81.5% and 85.1%, respectively, in 9-12y. Time estimates of AP3 were equivalent to DO for sitting/lying in 9-12y and stepping in all ages, but not for sitting/lying in 5-12y and standing in all ages. Underestimation of sitting/lying time was smaller in 9-12y (1.4%, limits of agreement [LoA]: -13.8-11.1%) compared to 5-8y (12.6%, LoA: -39.8-14.7%). Underestimation for stepping time was small (5-8y: 6.5%, LoA: -18.3-5.3%; 9-12y: 7.6%, LoA: -16.8-1.6%). Considerable overestimation was found for standing (5-8y: 36.8%, LoA: -16.3-89.8%; 9-12y: 19.3%, LoA: -1.6-36.9%). SB breaks were significantly overestimated (5-8y: 53.2%, 9-12y: 28.3%, p<0.001). Conclusions: AP3 showed acceptable accuracy for classifying postures, however estimates of time spent standing were consistently overestimated and individual error was considerable. Estimates of sitting/lying were more accurate for 9-12y. Stepping time was accurately estimated for all ages. SB breaks were significantly overestimated, although the absolute difference was larger in 5-8y. Surveillance applications of AP3 would be acceptable, however, individual level applications might be less accurate.
Original languageEnglish
Number of pages22
JournalJournal of Science and Medicine in Sport
Publication statusAccepted/In press - 6 Aug 2016

Keywords

  • sedentary behaviour
  • physical activity
  • child
  • accelerometry
  • activpal
  • breaks
  • thigh-based accelerometer
  • postural allocation

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    van Loo, C. M. T., Okely, A. D., Batterham, M. J., Hinkley, T., Ekelund, U., Brage, S., ... Cliff, D. P. (Accepted/In press). Validation of thigh-based accelerometer estimates of postural allocation in 5-12 year-olds. Journal of Science and Medicine in Sport.