Longitudinal changes in sedentary time and physical activity during adolescence

Abstract

BackgroundLow levels of physical activity and high time spent in sedentary activities have been associated with unfavourable health outcomes in adolescents. During adolescence, physical activity declines and sedentary time increases, however little is known about whether the magnitude of these changes differs within or between school-time, after-school time, or at weekends.MethodsAdolescents (n = 363) participating in the PEACH (Personal and Environmental Associations with Children’s Health) project provided accelerometer data at 12 and 15 years of age. Data were collected in 2008/2009 and 2012/2013. Time spent sedentary (<100 cpm), in light physical activity (LPA (100-2295 cpm) and in moderate to vigorous physical activity (MVPA: ≥ 2296 cpm) were generated for school-time, after-school time and for weekends using school-specific start and finish times. All data were analysed in 2014.ResultsThe proportion of time spent sedentary significantly increased during school (+8.23%, 95% CI = 7.35 to 9.13), after-school (+6.99%, 95% CI = 5.91 to 8.07) and at weekends (+6.86%, 95% CI = 5.10 to 8.62). A parallel decrease was found in the proportion of time spent in LPA during school (-7.62%, 95% CI = -8.26 to -6.98), after-school (-7.01%, 95% CI = -7.74 to -6.28) and at weekends (-6.72%, 95% CI = -7.80 to -5.65). The proportion of time spent in MVPA remained relatively stable during school (-0.64, 95% CI = -1.11 to -0.18), after-school (0.04%, 95% CI = -0.58 to 0.67) and at weekends (-0.14%, 95% CI = -1.18 to 0.90).ConclusionsObjectively measured sedentary time increased between 12 and 15 years of age during-school, after-school, and at weekends, suggesting that interventions aiming to reduce the age-associated changes in sedentary time are needed in all three time contexts. Future work should identify which sedentary activities change more than others to inform interventions which aim to minimise the increase in time spent sedentary during adolescence.

Determinants of Three-Year Change in Children’s Objectively Measured Sedentary Time

“…In addition, the analytical sample was relatively small due to participant attrition between baseline and follow-up assessments. Although sample retention was similar to that in other cohorts in this population [43] it is possible that some of our analyses were underpowered. However, most regression estimates were small, suggesting that the predominantly null findings cannot be attributed solely to a lack of statistical power.…”

Changes in compliance with school‐based physical activity recommendations in Spanish youth: The UP&DOWN longitudinal study

“…Brooke et al noted a MVPA decline in youths from ages 10 to 14 years, which was also notably higher among boys than girls. Several studies also showed a significant MVPA decrease among girls; however, other studies did not find a decrease in MVPA either for boys or for girls . This discrepancy between studies could be explained by their different follow‐up time and age of participants at baseline.…”

“…MVPA during the whole day significantly declined over the following 4‐ to 6‐years in English and American children aged 9‐ to 10‐years, but MVPA decline was not clear in 12‐year‐old English children . Likewise, total PA and MVPA during school hours decreased in English children over a 4‐year period, although in 12‐year‐old English children, only light PA (LPA) during school hours declined over 3 years . Research on longitudinal changes in PA during recess is limited to one study, where Ridgers et al showed a MVPA decline during recess in 5‐ to 6‐year‐old and 10‐ to 12‐year‐old Australian students over 3 and 5 years.…”

“…Given that inactivity increases with age, it is interesting to identify whether or not the school period contributes to the maintenance of MVPA levels in childhood. Several longitudinal studies have examined children and adolescents objectively measured PA levels during the whole day, but few of them have done it with school‐based PA . MVPA during the whole day significantly declined over the following 4‐ to 6‐years in English and American children aged 9‐ to 10‐years, but MVPA decline was not clear in 12‐year‐old English children .…”

“…Several longitudinal studies have examined children and adolescents objectively measured PA levels during the whole day, but few of them have done it with school‐based PA . MVPA during the whole day significantly declined over the following 4‐ to 6‐years in English and American children aged 9‐ to 10‐years, but MVPA decline was not clear in 12‐year‐old English children . Likewise, total PA and MVPA during school hours decreased in English children over a 4‐year period, although in 12‐year‐old English children, only light PA (LPA) during school hours declined over 3 years .…”