Impact of the COVID-19 Pandemic on Objectively Measured Physical Activity and Sedentary Behavior in Female Adolescents: A Longitudinal Study

Introduction: Numerous studies employing self-reported questionnaires and cross-sectional methodologies have demonstrated that social isolation resulting from the COVID-19 pandemic has markedly influenced the physical activity (PA) levels of youth.Objective: This study utilized modern accelerometers to assess the impact of the pandemic-related lockdown on PA levels of female adolescents, acknowledging the intrinsic limitations associated with the objectivity of self-reported PA.Methods: A cohort of 29 Iranian female students, aged between 15 and 18 years, utilized accelerometers for a duration of seven consecutive days, both prior to and during the pandemic. The analysis of PA levels of these students was conducted using descriptive statistics and paired t-tests.Results: The mean daily engagement in moderate-to-vigorous PA (MVPA) was documented at 46.8 minutes prior to the pandemic. However, this figure saw a significant reduction to 20.7 minutes during the pandemic, a level that is below the recommended international guidelines.Conclusion: This observation highlights the significant influence of lockdown measures on PA levels of female adolescents. It underscores the necessity for tailored strategies and initiatives that cater to the specific needs and preferences of young individuals, aimed at fostering an appropriate level of PA during periods of social restrictions, such as those experienced during the pandemic.