RESUMEN
Objective: To describe the impact of the COVID-19 pandemic-related restrictions (PR) in April and May 2020 on physical activity (PA), sedentary screen time (SST), and mental well-being (MWB) in German adolescents, and to analyze associations between these variables. Methods: The Münster District Government invited all secondary school students (aged 11-17) in the region to take part in the online survey that assessed PA, SST, and MWB. For data analysis, we calculated descriptive statistics and ran linear regression analysis. Results: 1,038 students (627 [60.4%] female; 14.18 [± 1.97] years) were included in the analysis. During the PR, a marked decline in overall PA (p < .001) and a significant increase (p < .001) in SST were observed. One-third of the students reported worrying more and being less satisfied with their lives since PR. A decrease in life satisfaction (ß = -.524, p < .001) as well as an increase in general worrying (ß = -.336, p = .015) were associated with a decrease in PA during PR. Conclusion: The results show that the restrictions led to a decrease in physical activity, which may have detrimental effects on the students' mental and physical health.