Associations between 24-hour movement behaviors and physical fitness in adolescents: A cross-sectional study using objective and subjective measures

This study aimed to investigate the association between objectively and subjectively measured 24-hour movement behaviors and physical fitness, and explore how the reallocation of time between 24-hour movement behaviors is associated with changes in physical fitness in adolescents. A total of 690 adolescents aged 14-17 years (55% girls) were included in this cross-sectional study conducted in Foshan, China. Moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior, and sleep were assessed using accelerometers in combination with a questionnaire. Physical fitness was tested through body mass index, forced vital capacity, 50-m sprint, standing long jump, sit-and-reach, gender-specific 800/1000-m run, and pull-ups/sit-ups. MVPA was significantly associated with better performance in the 50-m sprint (<i>β</i> = -0.29, 95% <i>CI</i> = -0.47 to -0.11) and the standing long jump (<i>β</i> = 14.50, 95% <i>CI</i> = 8.07 to 20.93), while LPA was significantly associated with sit-and-reach (<i>β</i> = 5.23, 95% <i>CI</i> = 2.11 to 8.35). Reallocating time to MVPA was associated with faster 50-m sprint and better standing long jump performance. These findings underscore the importance of MVPA for muscular strength and speed, providing evidence to support MVPA promotion within the 24-hour movement behavior framework to enhance physical fitness in adolescents.