Sedentary behavior, physical exercise, and cellphone use time among early adolescents: The moderating but not mediating role of self-control

This cross-sectional study aimed to explore the characteristics of cellphone use in Chinese early adolescents and the moderating and mediating role of self-control in the relationships among sedentary behavior, physical exercise, and cellphone use time. Using convenience sampling, we selected eight middle schools in Guangzhou, China. Two classes in the first grade of each middle school were randomly selected as the survey subjects. A total of 715 early adolescents (ages 11–13) completed surveys about the purpose of using cellphones (i.e., learning, entertainment, and others), cellphone use scenarios (i.e., sitting, standing, and moving), sedentary behavior, physical exercise, cellphone use time, and self-control. The results showed that the mean total daily cellphone use was 36.44 ± 37.42 min/day in early adolescents, who used cellphones mainly for studying, and 91.7% of them were seated when using cellphones. Cellphone use time was positively correlated with sedentary behavior, not correlated with physical exercise, and negatively correlated with self-control. Self-control played a moderating (not mediating) role not only between sedentary behavior and cellphone use time but also between physical exercise and cellphone use time. This study revealed the complex relationships among sedentary behavior, physical exercise, self-control, and cellphone use time. Our findings have significance for preventing the overuse of cellphones among early adolescents.