title: Convergent validity of pedometer and accelerometer estimates of moderate-to-vigorous physical activity of youth.
abstract: BACKGROUND
  Pedometer step-frequency thresholds (120 steps·min-1, SPM) corresponding to moderate-to vigorous intensity physical activity (MVPA) have been proposed for youth. Pedometers now have internal mechanisms to record time spent at or above a user-specified SPM. If pedometers provide comparable MVPA (P-MVPA) estimates to those from accelerometry, this would have broad application for research and the general public. The purpose of this study was to examine the convergent validity of P-MVPA to accelerometer-MVPA for youth.
  
  
  METHODS
  Youth (N = 149, average 8.6 years, range 5 to 14 years, 60 girls) wore an accelerometer (5-sec epochs) and a pedometer for an average of 5.7 ± 0.8 hours·day-1. The following accelerometer cutpoints were used to compare P-MVPA: Treuth (TR), Mattocks (MT), Evenson (EV), Puyau (PU), and Freedson (FR) child equation. Comparisons between MVPA estimates were performed using Bland-Altman plots and paired t tests.
  
  
  RESULTS
  Overall, P-MVPA was 24.6 min ± 16.7 vs. TR 25.2 min ± 16.2, MT 18.8 min ± 13.3, EV 36.9 min ± 21.0, PU 22.7 min ± 15.1, and FR 50.4 min ± 25.5. Age-specific comparisons indicated for 10 to 14 year-olds MT, PU, and TR were not significantly different from P-MVPA; for the younger children (5-8 year- olds) P-MVPA consistently underestimated MVPA.
  
  
  CONCLUSIONS
  Pedometer-determined MVPA provided comparable estimates of MVPA for older children (10-14 year-olds). Additional work is required to establish age appropriate SPM thresholds for younger children.
authors.affiliation: Dept of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA.
authors.forename: Michael William
authors.initials: MW
authors.lastname: Beets
authors.forename: Charles F
authors.initials: CF
authors.lastname: Morgan
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Banda
authors.forename: Daniel
authors.initials: D
authors.lastname: Bornstein
authors.forename: Won
authors.initials: W
authors.lastname: Byun
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mitchell
authors.forename: Lance
authors.initials: L
authors.lastname: Munselle
authors.forename: Laura
authors.initials: L
authors.lastname: Rooney
authors.forename: Aaron
authors.initials: A
authors.lastname: Beighle
authors.forename: Heather
authors.initials: H
authors.lastname: Erwin
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000367:Age Factors; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D016001:Confidence Intervals; D016552:Ergometry / Q000295:instrumentation*; D005260:Female; D006254:Hawaii; D006801:Humans; D007629:Kentucky; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D015203:Reproducibility of Results; D013022:South Carolina; D016138:Walking / Q000502:physiology*