RESUMEN
Objective An isotemporal substitution model was used to explore the associations between activities including 10 minutes per day of physical activity(PA),sedentary behavior(SB),and sleep(SLP),and depressive symptoms among vocational school students with and without depressive symptoms.Methods Questionnaire survey was conducted on grade one to grade three students attending vocational schools in Shanghai and Jiangsu Province from Dec 2021 to Jan 2022.Fourteen schools were selected using the convenience cluster sampling method.The selected students were categorized into depressive symptoms group and non-depressive symptoms group according to the Centre for Epidemiologic Studies Depression Scale(CES-D)scores.Results A total of 40 339 questionnaires were collected,of which 10 086 were able to clearly remember the time of physical activity in the past week,and 8 149 were valid after data cleaning.According to the valid questionnaires,5 496 students(67.44%)were in the non-depressive symptoms group and 2 653(32.56%)were in the depressive symptoms group.The mean age of the students were(16.70±1.19)years.In the non-depressive symptoms group,substituting moderate physical activity(MPA)for all the other behaviors was negatively associated with CES-D scores,while substituting vigorous physical activity(VPA)for MPA and SB was positively associated with CES-D scores.In the depressive symptoms group,substituting walking,SB,and SLP with MPA was negatively associated with CES-D scores,respectively.The associations of MPA substituted for walking,SB,and SLP with CES-D scores were much stronger in the depressive symptoms group than in the non-depressive symptoms group.Conclusion The detection rate of depressive symptoms was high among vocational students.Substituting MPA for walking,SB,and SLP were negatively associated with CES-D scores,with a stronger association observed in the depressive symptoms group than in the non-depressive symptoms group.
