Are adolescents really being sedentary or inactive when at school? An analysis of sedentary behaviour and physical activity bouts
This study analysed physical activity (PA) and sedentary behaviour (SB) performed in bouts during schooltime. Adolescents of two schools answered a questionnaire, had their height and weight measured and wore accelerometers during schooltime. Moderate-to-vigorous intensity PA was estimated in bouts of 2, 5 and 10 min, and SB in bouts of 5, 10, 30 and 60 min. Body mass index was calculated, and adolescents were classified as overweight or normal weight. Frequency, duration and volume of PA and SB were calculated for the whole sample and for those who performed at least one bout weekly. PA and SB differences between gender and weight status were tested using Mann-Whitney and t tests. A total of 415 adolescents (54% girls, 12.3 ± 1.3 years old, 34.6% overweight) performed 0.1 (± 0.2), 0.2 (± 0.5) and 0.4 (± 0.6) bouts of 10, 5 and 2 min of PA, and 10.6 (± 2.0), 6.0 (± 1.3), 1.1 (± 0.9) and 0.4 (± 0.5) bouts/day of 5, 10, 30 and 60 min of SB, respectively. Boys accumulated less SB and more PA in bouts. No differences were found for weight status.
What is Known:
• Adolescents are not engaging in enough PA and are accumulating large volumes of SB, which might negatively impact their health.
• Schools play an important role in daily overall PA, with opportunities such as PE classes and recesses. But most classes are still undertaken in seated positions.
What is New:
• Adolescents hardly engage in bouted (> 10 m) PA when at school., and most SB is accumulated in short bouts (≤ 10m).
• Weight status was not associated with bouted PA or SB at school
KeywordsAccelerometry Exercise Youth School
Moderate-to-vigorous intensity physical activity
Metabolic equivalent of task
Body mass index
The authors would like to thank all the students that participated in the study, and the researchers from the Research Centre of Physical Activity and Health, Research Centre of Kineanthropometry and Human Performance, and the staff of the Board of Education of Florianopolis for their contribution to the research.
BGGC: contributed to the conception of the study, data collection, data analysis, and drafted the manuscript.
KSS: contributed to the analysis, interpretation of data, and revised and reviewed the manuscript.
LEAM: contributed to the data management and initial analysis, interpretation of data, and revised and reviewed the manuscript.
GM: participated in the study design and conduction, data collection, revised and reviewed the manuscript.
LRAL: participated in the study design and conduction, data collection, revised and reviewed the manuscript.
ELP: conceptualized the study design and coordinated data collection, critically reviewed the manuscript.
All authors have revised and approved the manuscript as submitted.
This study is financially supported by the National Council for Scientific and Technological Development (CNpQ - 474184/2013-7). BGGC, GM and LRAL received scholarships from the Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES). This study is registered at www.clinicaltrials.gov (Identifier NCT02719704).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures were approved by the Ethics Committee on Human Research of the Carmela Dutra Maternity Hospital (process 780.303), and all participants provided a consent form signed by their respective legal guardians.
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