Longitudinal Changes in Physical Activity Over Two Years in Young Children

Background Limited information is available about changes over time in objectively measured daily physical activity in young children. This study evaluates if accelerometer-measured physical activity tracks or changes over two years.

Methods Daily physical activity was assessed by the Actigraph accelerometer for four consecutive days in 167 children (boys n=90, girls n=77) aged 7.9-11.1 years at baseline. Follow-up measurements were performed 2.0±0.1 yrs later (range 1.9-2.1 yrs). General physical activity (GPA) was considered to be mean count per minute. Minutes of light physical activity (LPA), moderate physical activity (MPA), moderate and vigorous physical activity (MVPA) as well as vigorous physical activity (VPA) per day were calculated.

Results Spearman rank order correlation indicated low-moderate tracking of MPA, MVPA, VPA in both boys and girls, and GPA in boys (R=0.24-0.40, P<0.05). No significant tracking was detected for LPA, and GPA in girls. Several physical activity variables were lower at follow-up: In girls; LPA (-12%), and in boys; GPA (-14%), LPA (-10%), and VPA (-27%).

Conclusion This study shows that accelerometer-measured physical activity tracks at a low-moderate degree from age 10 to age 12 years. It is of concern that several physical activity variables were lower at follow-up in both boys and girls.