5-year changes in afterschool physical activity and sedentary behavior

Background: The afterschool period holds promise for the promotion of physical activity, yet little is known about the importance of this period as children age.

Purpose: To examine changes in physical activity of children aged 5-6 years and 10-12 years and their sedentary time in the afterschool period over 3 and 5 years, and to determine the contribution of this period to daily physical activity and sedentary behavior over time.

Methods: Data from two longitudinal studies conducted in Melbourne, Australia, were used. Accelerometer data were provided for 2053 children at baseline (Children Living in Active Neighbourhoods Study [CLAN]: 2001; Health, Eating and Play Study [HEAPS]: 2002/2003); 756 at 3-year follow-up (time point 2 [T2]); and 622 at 5-year follow-up (T3). Light (LPA), moderate (MPA) and vigorous (VPA) physical activity were determined using age-adjusted cut-points. Sedentary time was defined as ≤ 100 counts/minute. Multilevel analyses, conducted in April 2012, assessed change in physical activity and sedentary time and the contributions of the afterschool period to overall levels.

Results: Afterschool MPA and VPA decreased among both cohorts, particularly in the younger cohort, who performed less than half of their baseline levels at T3 (MPA: T1=24 minutes; T3=11 minutes; VPA: T1=12 minutes; T3=4 minutes). LPA also declined in the older cohort. Afterschool sedentary time increased among the younger (T1=42 minutes; T3=64 minutes) and older cohorts (T1=57 minutes; T3=84 minutes). The contribution of the afterschool period to overall MPA and VPA increased in the older cohort from 23% to 33% over 5 years. In the younger cohort, the contribution of the afterschool period to daily MPA and VPA decreased by 3% over 5 years.

Conclusions: The importance of the afterschool period for children's physical activity increases with age, particularly as children enter adolescence.