Declines in Physical Activity and Cardiorespiratory Fitness After Implementing new National School Guidelines

Abstract

PurposeWe examined whether introduction of national guidelines limiting sports club activities at school was associated with adolescents' exercise and cardiorespiratory fitness. MethodsWe conducted interrupted time-series analysis to quantify the changes in prefecture-level aggregated data on exercise or sports activities and 20-m shuttle run (indicator of cardiorespiratory fitness) among adolescents in Japan before (2013–2017) and after (2018–2022) the introduction of the guidelines using data from the National Survey of Physical Fitness, Athletic Performance and Exercise Habits. ResultsThe introduction of the guidelines was associated with reductions in exercise and sports activities duration (boys, −4.8 [95% CI −5.9, −3.8] min/day; girls, −5.5 [95% CI −6.2, −4.8] min/day) and performance of 20-m shuttle run (boys, −1.2 [95% CI −1.4, −1.0] laps; girls, −2.3 [95% CI −2.5, −2.2] laps). DiscussionAfter introducing guidelines limiting sports club activities at school, levels of exercise or sports and cardiorespiratory fitness declined among adolescents.