The aim of the study is to determine the trajectories of physical activity and depressive symptoms and their reciprocal relationship among community-dwelling older adults in the COVID-19 pandemic era. The study population consisted of a cohort of 511 participants aged 60 years and over, who were recruited from eight community health centers in Ya'an, China. The Physical Activity Scale for the Elderly and the Patient Health Questionnaire were respectively used to measure physical activity and depressive symptoms at three time points: before the COVID-19 outbreak (T(0)), during the outbreak peri...