title: Comparison of two approaches to structured physical activity surveys for adolescents.
abstract: OBJECTIVE
  To compare the test-retest reliability, convergent validity, and overall feasibility/ usability of activity-based (AB) and time-based (TB) approaches for obtaining self-reported moderate-to-vigorous physical activity (MVPA) from adolescents.
  
  
  METHODS
  Adolescents (206 females and 114 males) completed two 3-d physical activity recalls using the AB and TB surveys, which contained identical lists of physical activities. The participants wore an MTI Actigraph accelerometer for the same period.
  
  
  RESULTS
  The TB instrument took about 3 min longer to complete (P = 0.022). Overall 2-d test-retest correlations for MVPA were similar for the two surveys (r = 0.676 and 0.667), but the girls had higher reliability on the AB survey than the boys (girls: r = 0.713; boys: r = 0.568). The overall 3-d correlations for MVPA surveys and Actigraph counts varied by gender (girls: AB = 0.265 vs TB = 0.314; boys: AB = 0.340 vs TB = 0.277). Correlations for vigorous physical activity and Actigraph counts were higher for the AB than for the TB (r = 0.281 vs 0.162). As the interval between completing the surveys and the days being recalled increased, reliability and validity were lower, especially for the AB survey.
  
  
  CONCLUSIONS
  For both genders, either approach is acceptable for obtaining MVPA information on a single day, but the TB approach appears to be slightly favored over the AB approach for obtaining multiple days of MVPA. A 3-d recall period appears to be too long for accurate recall of MVPA information from either instrument. For both genders, the surveys overestimated activity levels; thus, self-reports should be supplemented with objective data.
authors.affiliation: Department of Exercise and Sport Science, CB#8700, Fetzer Gym, University of North Carolina, Chapel Hill, NC 27599-8700, USA. exphys@email.unc.edu
authors.forename: Robert G
authors.initials: RG
authors.lastname: McMurray
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Ring
authors.forename: Margarita S
authors.initials: MS
authors.lastname: Treuth
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Welk
authors.forename: Russell R
authors.initials: RR
authors.lastname: Pate
authors.forename: Kathryn H
authors.initials: KH
authors.lastname: Schmitz
authors.forename: Julie L
authors.initials: JL
authors.lastname: Pickrel
authors.forename: Vivian
authors.initials: V
authors.lastname: Gonzalez
authors.forename: M Jaoa C A
authors.initials: MJ
authors.lastname: Almedia
authors.forename: Deborah Rohm
authors.initials: DR
authors.lastname: Young
authors.forename: James F
authors.initials: JF
authors.lastname: Sallis
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D011939:Mental Recall; D010809:Physical Fitness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity