title: At the Mercy of the Gods: Associations Between Weather, Physical Activity, and Sedentary Time in Children.
abstract: OBJECTIVE
  This study investigated associations between weather conditions, physical activity, and sedentary time in primary school-aged children in Australia and Canada.
  
  
  METHODS
  Cross-sectional data on 9-11-year-old children from the Australian (n = 491) and Canadian (n = 524) sites of the International Study of Childhood Obesity, Lifestyle and the Environment were used. Minutes of daily moderate-to-vigorous-physical-activity (MVPA) and sedentary time were determined from 7-day, 24-h accelerometry (Actigraph GT3X+ triaxial accelerometer). Day-matched weather data (temperature, rainfall, snowfall, relative humidity, wind speed) were obtained from the closest weather station to participants' schools. Covariates included parental highest education level, day type, sex, and BMI z-scores. Generalized mixed model analyses allowing for clustering of participants within schools were completed. Scatterplots with Loess curves were created for maximum temperature, MVPA, and sedentary time.
  
  
  RESULTS
  Daily maximum temperature was significantly associated with MVPA and sedentary time in Australia (MVPA p = .05, sedentary p = .01) and Canada (p < .001, p = .001). Rainfall was negatively associated with MVPA in Australia (p < .001) and positively associated with sedentary time in Canada (p = .02).
  
  
  CONCLUSIONS
  MVPA and sedentary time appear to be optimal when the maximum temperature ranges between 20°C and 25°C in both countries. The findings have implications for study design and interpretation for surveillance and intervention studies.
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia.
authors.forename: Lucy Kate
authors.initials: LK
authors.lastname: Lewis
authors.forename: Carol
authors.initials: C
authors.lastname: Maher
authors.forename: Kevin
authors.initials: K
authors.lastname: Belanger
authors.forename: Mark
authors.initials: M
authors.lastname: Tremblay
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Chaput
authors.forename: Tim
authors.initials: T
authors.lastname: Olds
mesh_terms: D056044:Actigraphy; D001315:Australia; D002170:Canada; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D057185:Sedentary Behavior; D014887:Weather