Last updated on 5-12-2024 by Thérésa Lebacq
Why do we study sedentary time of adolescents aged 10 to 17 years?
- Sedentary behaviours refer to any waking activities carried out while sitting or lying down, and characterised by low energy expenditure. It can occur in several contexts such as at school (e.g. sitting in class), at home (e.g. reading a book, watching television) or during transportation (e.g. sitting in a car).
- In adolescents, higher sedentary time is associated with increased adiposity, poorer cardiometabolic health and fitness, reduced sleep duration, and lower health-related quality of life.
- The World Health Organization (WHO) recommends that children and adolescents aged 5 to 17 years should limit the time spent being sedentary, particularly screen time during leisure activities.
How do we do it?
- We used accelerometers to objectively measure the amount and intensity of physical activity in adolescents. Accelerometers provide an accurate, reliable, and practical objective measure of physical activity. It measures accelerations caused by bodily movements and makes the distinction between time spent in different levels of physical activity. In adolescents, data from accelerometers are more accurate than data obtained from questionnaires which are often subject to recall bias and social desirability.
- Adolescents aged 10 to 17 years were asked to wear a triaxial accelerometer GT3X+ Actigraph® during seven consecutive days including two weekend days, during waking hours (except during water-based activities). The participants also registered in a diary all activities performed when the accelerometer was removed (except for sleeping during the night). This diary was used to complete the data provided by the accelerometers and provide a full overview of the amount and the intensity of physical activity.
- The total sedentary time was calculated for each day during which the accelerometer was worn. The average daily sedentary time was then calculated for each individual, separately for week and weekend days.
Key results
On weekdays, adolescents aged 10 to 17 years spend on average 7 hours 55 minutes/day in sedentary activities.
On weekend days, adolescents aged 10 to 17 years spend on average 7 hours 7 minutes/day in sedentary activities.
Daily sedentary time on both weekdays and weekends decreased by approximately one hour among adolescents between 2014-2015 and 2022-2023.
Sex
Average daily sedentary time among adolescents aged 10 to 17 years on week and weekend days, by sex, Belgium: 2022-2023
- Crude = results weighted for season, age, sex, and socioeconomic status.
- In 2022-2023, adolescents aged 10 to 17 years spent on average 475 minutes/day (i.e. 7 hours 55 minutes/day) in sedentary activities on weekdays and 427 minutes/day (i.e. 7 hours 7 minutes/day) on weekend days.
- Girls and boys have similar daily sedentary time on week and weekend days.
Educational level
Average daily sedentary time among adolescents aged 10 to 17 years on week and weekend days, by educational level, Belgium: 2022-2023
- Crude = results weighted for season, age, sex, and socioeconomic status.
- The educational level is calculated at the household level by considering the highest diploma obtained by: (i) the respondents or their partner for adults (aged 18 years and above), or (ii) the father and mother (or carer, if applicable) for children and adolescents (aged 3 to 17 years). However, for simplicity, we refer to the educational level of individuals rather than the educational level of their households.
- On week and weekend days, the average sedentary time in adolescents is similar across different educational levels.
Region and year
Average daily sedentary time among adolescents aged 10 to 17 years on (A) week and (B) weekend days, by region and year, Belgium: 2022-2023
A. On weekdays
B. On weekend days
- Adjusted = results weighted for season, age, sex and socioeconomic status, and adjusted according to age and sex based on linear regression model (using the Belgian population of 2022-2023 as reference).
- At the national level, adolescents aged 10 to 17 years spent, on average, less time per day in sedentary activities in 2022-2023 compared to 2014-2015. This decrease is observed during both the week and the weekend.
- Similar declines were observed in both Flanders and Wallonia between 2014-2015 and 2022-2023.
- In 2022-2023, adolescents living in Wallonia had lower daily sedentary time on weekends (408 minutes or 6 hours 48 minutes/day) compared to adolescents living in Flanders (434 minutes or 7 hours 14 minutes/day).
Sex and year
Average daily sedentary time among adolescents aged 10 to 17 years on (a) week and (b) weekend days, by sex and year, Belgium: 2022-2023
A. On weekdays
B. On weekend days
- Adjusted = results weighted for season, age, sex and socioeconomic status, and adjusted according to age and sex based on linear regression model (using the Belgian population of 2022-2023 as reference).
- The average daily sedentary time decreased for both girls and boys between 2014-2015 and 2022-2023.
- While the decrease in sedentary time on weekdays is similar for boys and girls, the decrease observed on weekends is more pronounced for girls than for boys.
Please cite this page as: Sciensano. Physical activity and sedentary behaviour in adolescents: Sedentary time, Food Consumption Survey 2022-2023, December 2024, Brussels, Belgium, https://www.sciensano.be/en/results-national-food-consumption-survey-2022-2023/physical-activity-and-sedentary-behaviour-adolescents-between-10-and-17-years/sedentary-time