The importance of physical activity, as one of the crucial resources for maintaining and improving physical health, was diminished during the Covid-19 pandemic. Except for the impact it has on physical health, physical activity may have various psychological benefits, especially during the development period of adolescence. The current findings of physical activity show that adolescents are more physically inactive during the pandemic than usual. Also, there are increasingly negative psychological outcomes in adolescents. The purpose of this study was to explore the levels of physical activity, negative affectivity, coping and preoccupation with the pandemic in an adolescent sample. The study involved 2409 adolescents (53.5% girls, 46.5% boys) from elementary and high schools aged 10 to 19. The Depression, Anxiety and Stress Scale (DASS-21) was applied, and information about levels of physical activity, coping and preoccupation with pandemic and isolation measures were collected. Participants answered on a Likert-type scale. Findings of this research show that on average male adolescents are more likely to engage in physical activities than females. Also, a relation of physical inactivity distress and preoccupation was obtained for adolescent girls. No similar finding was found for males. However, very high physical activity (five or more times a week) was a protective factor for coping and preoccupation with coronavirus infection. The conclusion of this research indicates that levels of physical activity have a different effect on male and female adolescents during the Covid-19 pandemic. It can be concluded that female adolescents that are less physically active are more at risk of depression, anxiety and stress.