The youths’ study and physical activity (PA) patterns may have been affected by lockdown measures due to COVID-19. This study aimed to reveal how youths’ study and PA patterns had changed after implementing and lifting COVID-19 lockdown in China.

The COVID-19 Impact on Lifestyle Change Survey (COINLICS) was used, where 10082 youth participants voluntarily reported their study and PA patterns in the 3 periods before, during, and after COVID-19 lockdown. PA was measured as the weekly frequency of engaging in active transport for commuting/errands, leisure-time walking, leisure-time moderate-/vigorous-intensity physical activity (MVPA), and moderate-/vigorous-intensity housework (MVH); study patterns were measured as the daily average study time and the major study modes. We assessed differences of these variables across educational levels, sex, and periods.

The significant decreases were generally observed during lockdown in the frequency of active transport for commuting/ errands (1.3 to 0.2 days/ week), leisure-time walking (1.0 to 0.2 days/ week), leisure-time MVPA (0.7 to 0.3 days/ week), and MVH (2.3 to 2.0 days/ week), with heterogeneities existing between sexes and across educational levels, except for the increase in MVH engagement among graduate students, especially female (1.5 to 2.4 days/ week). Rebounds were observed in the frequency of all activities except MVH after lifting lockdown (2.0 to 1.9 days/ week). The average study time generally increased during lockdown, with more youths studying for 1 - 4 hours/ day and less studying for < 1 hour/ day, and further increased after lockdown. A main shift of study modes has been from in-class to online study after implementing lockdown.

The youths’ PA level have generally decreased, and study patterns significantly changed during and after lockdown in China. Our results would inform policymakers and educational administrators of the declined PA levels and changed study patterns among youths during COVID-19 lockdown for better policy making. In - class and/ or extracurricular PA programs could be designed to counteract those effects under cooperation of youths’ parents.