title: Assessing Children's Time-Use in Relation to Physical Fitness and Risks of Obesity and Diabetes: Development of a New Physical Activity Self-Report Instrument.
abstract: BACKGROUND
  This study introduces a novel self-report instrument to measure children's time-use in physical and sedentary activities and examines the relationships between children's time-use and physical fitness and risks of obesity and diabetes.
  
  
  METHODS
  The new instrument utilizes a series of timelines, each representing an activity type. 188 children (53% girls) aged 10 to 14 year-old participated in the study. Their time-use data for two weekdays and one weekend day were collected. Anthropometrics and cardiovascular fitness were measured and children's BMI z-score and PACER z-score were computed. One-time blood draw for fasting glucose and insulin were used to calculate insulin resistance using homeostasis model assessment for insulin resistance (HOMAIR).
  
  
  RESULTS
  The reliability assessment of this instrument indicated a moderately reproducible procedure (ICC > 0.6) for six activity types. The validity correlation for motorized travel time was high (r = 0.226,P< 0.05) between self-report instrument and GPS tracks. PACER z-score was positively correlated with time-uses of play (r = 0.159,P< 0.05), and organized sports (r = 0.198,P< 0.05); and was highly inversely correlated with BMI z-score (r = -0.441,P< 0.0001) and HOMAIR(r = -0.472,P< 0.0001). Overall, only 14% of the children had physical activity for more than 60 minutes daily over three observation days.
  
  
  CONCLUSIONS
  This instrument is particularly useful in assessing children's activity patterns, especially for specific physical activities. The new instrument provides a reproducible measure of children's perception of their activities. Our results emphasize the temporal context which is critical to formulating effective interventions targeting physical activity increase in children. Further efforts are needed to understand the differences between activity time obtained by the new self-report instrument and GPS tracks.
authors.affiliation: Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI.
authors.forename: Y
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI.
authors.forename: J
authors.initials: J
authors.lastname: Guo
authors.affiliation: Nutritional Sciences, University of Wisconsin-Madison, Madison, WI.
authors.forename: M
authors.initials: M
authors.lastname: Santiago-Torres
authors.affiliation: Nutritional Sciences, University of Wisconsin-Madison, Madison, WI.
authors.forename: D
authors.initials: D
authors.lastname: Schoeller
authors.affiliation: Institute for Clinical and Translational Research, University of Wisconsin-Madison, Madison, WI.
authors.forename: S
authors.initials: S
authors.lastname: Esmond
authors.affiliation: Department of Pediatrics, University of Wisconsin-Madison, Madison, WI.
authors.forename: D
authors.initials: D
authors.lastname: Allen
authors.affiliation: United Community Center, Milwaukee, WI.
authors.forename: M
authors.initials: M
authors.lastname: Henderson
authors.affiliation: United Community Center, Milwaukee, WI.
authors.forename: A
authors.initials: A
authors.lastname: Rendon
authors.affiliation: Department of Pediatrics, University of Wisconsin-Madison, Madison, WI.
authors.forename: A
authors.initials: A
authors.lastname: Carrel
keywords: Activity Patterns; Metabolic Health; Reliability; Validity