Seasonal Variation in Objectively Measured Physical Activity Among Finnish Boys and Girls Aged 7 to 15 Years

Aim The aim was to evaluate seasonal variations in physical activity. This study is part of the pilot phase of the Finnish Schools on the Move program in 2010-2012.

Methods The study population consisted of 119 boys and girls from grades 1 to 9 (7 to 15 years of age) from 6 schools. Children’s physical activity was monitored four times over the 1.5-year follow-up period: in autumn 2010, spring 2011, autumn 2011, and spring 2012. Physical activity was assessed objectively using the ActiGraph accelerometer for 7 consecutive days. The cut-off value of 2,296 counts per minute [1] was used for moderate-to-vigorous physical activity (MVPA). Seasonal variations in MVPA time, and the proportion of children meeting Finnish recommendations of at least 60 minutes of MVPA/day [2], were analysed. The results were examined as a whole group and in two age-groups: younger (grades 1-6) and older (grades 7-9) children.

Results Mean MVPA time was 55 min/day in autumn 2010 and 52 min/day in autumn 2011. In spring 2011 and spring 2012, mean MVPA times were 60 and 56 min/day, respectively. The difference in MVPA time between autumn and spring was 4 min/day, which equals 8% of MVPA time (p<0.005 for seasonal difference). The percentage of children meeting the 60 minutes of MVPA/ day in autumn was 39% in 2010 and 34% in 2011; in spring the respective values were 48% in 2011 and 40% in 2012. The results were similar in both genders and age-groups. On average, younger children had 22 min/day more MVPA time than older children (p<0.001). For younger children there was no seasonal difference in weekend MVPA times.

Conclusions Finnish school-aged children are more active in spring than in autumn. The mean difference in MVPA time between these two seasons was 4 min/day, meaning 8% of total MVPA time.

References [1] Evenson, K.R.; Catellier, D.J.; Gill, K.; Ondrak, K.S. and McMurray, R.G. Calibration of two objective measures of physical activity for children. Journal of sports sciences, 2008. 26(14), 1557. [2] Tammelin, T. and Karvinen, J. (editors). Physical activity recommendations for school-aged children. Finnish report, abstract in English. 2008. Opetusministeriö ja Nuori Suomi ry. Reprotalo Lauttasaari Oy, Helsinki.