Effects of Weather on Objectively Assessed Physical Activity in Danish Preschool Children

Aim The weather may be a barrier to physical activity but objective assessment of this hypothesis is scarce. This study evaluated the effect of temperature and rainfall on the daily physical activity of Danish preschool children. Furthermore within-day variability in physical activity was studied for both weekend and weekdays.

Methods The study was cross sectional in design and included children aged 5 to 6 years (n=636 invited) enrolled at 43 randomly selected Danish preschools. Children’s physical activity was assessed by accelerometry over a one-week period (Actigraph GT1M & GT3X) and weather data were obtained from the Danish Meteorological Institute. The total data collection period for physical activity lasted 4 weeks spanning the months of May and June 2009, during which the weather conditions varied substantially (mean daily temperature range 9-20°C; Total daily rainfall range 0-20.5 mm).

Results During preschool time a significant interaction between rainfall and time of day was observed (p<0.001). In the afternoon hours rainfall was associated with an approximately 29 % decrease in physical activity — corresponding to 360 counts per minute. Before noon rainfall decreased physical activity by 11 % (89 counts per minute). Mean daily temperature was positively related to physical activity but only during before noon hours and the effect size was relatively small. During weekends the same overall pattern was observed, however absolute levels of physical activity were lower.

Conclusion Total rainfall has a substantial effect on preschool children’s physical activity and should be considered as a methodological point of attention when comparing physical activity across different locations or periods — in particular when physical activity is assessed over a limited number of monitoring days.