The longitudinal associations of physical activity, time spent outdoors in nature and symptoms of depression and anxiety during COVID-19 quarantine and social distancing in the United States

Stressors associated with COVID-19 pandemic stay-at-home orders are associated with increased depression and anxiety and decreased physical activity. Given that physical activity and time spent outdoors in nature are associated with improved mental health, we examined the longitudinal association of these variables during the pandemic. Over 20,000 adults who participated in the U.S. Kaiser Permanente Research Bank, did not report COVID-19 symptoms, and responded to an online baseline and 3 follow-up surveys over approximately 3 months formed the cohort. Physical activity was assessed from a modified survey, time spent outdoors was assessed from one question, and anxiety and depression scores were assessed from validated instruments. Almost 60% were women, 82.8% were non-Hispanic white, and more than 93% of respondents were over the age of 50. Less in-person contact with friends and visiting crowded places was highly prevalent (>80%) initially and decreased somewhat (>70%). Participants in the lowest physical activity category (no physical activity) had the highest depression and anxiety scores compared to each successive physical activity category (p < 0.001). Spending less time outdoors was associated with higher depression and anxiety scores. This effect was greater for participants in the younger age categories compared with older age categories. The effect of less time spent outdoors on anxiety (p = 0.012) and depression (p < 0.001) scores was smaller for males than females. Results suggest that physical activity and time outdoors is associated with better mental health. People should be encouraged to continue physical activity participation during public health emergencies.