Associations between Sedentary Time and Sedentary Patterns and Cardiorespiratory Fitness in Chinese Children and Adolescents

The increase in sedentary behavior in children and adolescents has become a worldwide public health problem. This study aimed to explore the associations between sedentary time (ST) and sedentary patterns (SP) and the cardiorespiratory fitness (CRF) of Chinese children and adolescents. The CRF of 535 participants was determined using a 20-m shuttle run test. ST and SP were measured with accelerometers. Questionnaires were used to investigate the different types of ST. Multiple linear regression models were used to test the associations between ST and SP and CRF. In this study, only some ST and SP indicators were found to be significantly associated with CRF in girls. With each additional 10 min of screen time or passive traffic time, VO2max decreases by 0.06 mL/kg/min (B = -0.006, 95% CI: -0.010 similar to-0.001) and 0.31 mL/kg/min (B = -0.031, 95% CI: -0.061 similar to-0.002), respectively, with MVPA control. With each additional 10 min of breaks in ST or duration of breaks in ST, VO2max increases by 0.41 mL/kg/min (B = 0.041, 95% CI: 0.007 similar to 0.076) and 0.21 mL/kg/min (B = 0.021, 95% CI: 0.007 similar to 0.035), respectively, with control total ST. Breaks in ST (B = 0.075, 95% CI: 0.027 similar to 0.123) and the duration of breaks in ST (B = 0.021, 95% CI: 0.012 similar to 0.146) were positively correlated with CRF when controlling for LPA, but these associations were not significant when controlling for MVPA (B = 0.003, 95% CI: -0.0420.similar to 048; B = 0.001, 95% CI: -0.024 similar to 0.025). The total ST of children and adolescents was found to not be correlated with CRF, but when ST was divided into different types, the screen time and passive traffic time of girls were negatively correlated with CRF. More breaks in ST and the duration of breaks in ST were positively associated with higher CRF in girls. MVPA performed during breaks in ST may be the key factor affecting CRF. Schools and public health departments should take all feasible means to actively intervene with CRF in children and adolescents.

Automated summary

This study aimed to explore the associations between sedentary time and sedentary patterns and the cardiovascular fitness of Chinese children and adolescents. The results showed that screen time and passive traffic time were negatively correlated with cardiovascular fitness in girls, while breaks in sedentary time and the duration of breaks were positively correlated. Moderate-to-vigorous physical activity during breaks in sedentary time may be a key factor affecting cardiovascular fitness.