ABSTRACT
Objective@#To explore the association between light intensity physical activity (LPA) and sedentary behavior (SB) with body composition, so as to provide data references for improving adolescent physical health.@*Methods@#From August 2020 to January 2021, general information of 694 students in grade one of a high school in Foshan City was collected, and the 24 hour activity behavior and body composition of the students were measured objectively by triaxial accelerometer and bioelectrical impedance tester. Dual component multivariate regression and dual compositional isotemporal substitution model were used to explore the relationship between LPA and SB and body composition.@*Results@#LPA was associated with lower fat relative dominance (FRD) (male weekends FRD=-21.44%, female weekly FRD=-17.83%, weekdays FRD=-18.27%, P <0.05), and LPA was also associated with higher muscle relative dominance (MRD) and bone relative dominance (BRD) (male weekends MRD=12.78%, BRD= 12.87 %; female weekly MRD=11.64%, BRD=9.01%; female weekdays MRD=12.02%, BRD=9.23%, P <0.05). Replacing sedentary behavior (SB) with 10 minutes of LPA could reduce fat proportion [male:weekly -0.15(-0.26--0.04), weekdays -0.12 (-0.22--0.02); female:weekly -0.18(-0.27--0.08), weekdays -0.16(-0.25--0.07)) and increase muscle proportion (male:weekly 0.14(0.03-0.24), weekdays 0.11(0.02-0.21); female:weekly 0.17(0.07-0.26), weekdays 0.15(0.07-0.24)].@*Conclusion@#Interrupting continuous SB with LPA can serve as an intervention measure to promote physical health and fitness in adolescents. School should encourage students to engage in frequent LPA during breaks and after school activities, while avoiding prolonged SB.