Intervention to Improve 24-Hour Movement Behaviors in University Students

This randomized controlled behavioural study was conducted to evaluate the effectiveness of a personalized, online intervention based on the Multi-Process Action Control (M-PAC) framework in optimizing the time-use composition of 24-hour movement behaviours among university students. Participants were randomly assigned to either an intervention group or a control group. The intervention group received a personalized behavioural program delivered via WeChat. The program was designed to support more optimal allocation of daily time across physical activity, sedentary behaviour, and sleep by targeting key behavioural processes, including reflective, regulatory, and reflexive mechanisms. Intervention content included individualized feedback and behaviour-change support tailored to each participant's movement behaviour profile. The control group did not receive intervention materials and continued their usual daily routines. The primary outcome was the time-use composition of 24-hour movement behaviours, defined as the relative distribution of time allocated to physical activity, sedentary behaviour, and sleep within a finite 24-hour period. Secondary outcomes comprised psychological constructs related to behaviour regulation, derived from the Multi-Process Action Control (M-PAC) framework. These constructs included affective attitude, instrumental attitude, perceived capability, perceived opportunity, intention, planning, self-monitoring, identity, and habit, and were assessed using validated Chinese-language self-report questionnaires with established psychometric properties. In the present study, healthy time allocation of 24-hour movement behaviours was operationally defined in accordance with the Canadian 24-Hour Movement Guidelines for Adults, which recommend regular engagement in moderate-to-vigorous physical activity, participation in light-intensity physical activity across the day, limited recreational screen time, adequate sleep duration, and regular muscle-strengthening activities. The study involved a non-clinical population and did not include biomedical or medical health outcomes. The study protocol was approved by the institutional ethics committee, and written informed consent was obtained from all participants prior to participation.