Intervention to Improve 24-Hour Movement Behaviors in University Students

Time allocation of 24-hour movement behaviours was objectively assessed using a waist-worn ActiGraph GT3X accelerometer worn continuously for seven consecutive days.

Affective attitude toward healthy time allocation of 24-hour movement behaviours was assessed using three bipolar adjective pairs (unpleasant-pleasant, boring-interesting, and unenjoyable-enjoyable) adapted from established Theory of Planned Behaviour questionnaires (https://people.umass.edu/aizen/pdf/tpb.measurement.pdf). Participants responded to a common stem ("In the next week, compliance with healthy time allocation of 24-hour movement behaviours is …"), followed by three items. Responses were recorded on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). A mean score was calculated across the three items, with higher scores indicating a more positive affective attitude.

Instrumental attitude was assessed using three bipolar adjective pairs (harmful-beneficial, worthless-valuable, and bad-good) adapted from established Theory of Planned Behaviour measures (https://people.umass.edu/aizen/pdf/tpb.measurement.pdf

). Participants responded to a common stem ("In the next week, compliance with healthy time allocation of 24-hour movement behaviours is …"), followed by three items (e.g., "In the next week, compliance with healthy time allocation of 24-hour movement behaviours is harmful-beneficial"). Responses were recorded on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). A mean score was calculated across the three items, with higher scores indicating a more positive instrumental attitude.

Perceived capability was assessed using three items adapted from established Theory of Planned Behaviour measures (https://people.umass.edu/aizen/pdf/tpb.measurement.pdf

). Participants responded to a common stem ("In the next week, compliance with healthy time allocation of 24-hour movement behaviours is …"), followed by items assessing perceived ease and capability (e.g., "It is easy for me to comply with healthy time allocation of 24-hour movement behaviours in the next week"). Responses were recorded on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). A mean score was calculated across the three items, with higher scores indicating greater perceived capability.

Intention was assessed using three items adapted from established Theory of Planned Behaviour measures (https://people.umass.edu/aizen/pdf/tpb.measurement.pdf

). Participants responded to a common stem ("In the next week, compliance with healthy time allocation of 24-hour movement behaviours is …"), followed by items assessing behavioural intention (e.g., "I intend to comply with healthy time allocation of 24-hour movement behaviours in the next week"). Responses were recorded on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). A mean score was calculated across the three items, with higher scores indicating stronger intention.

Perceived opportunity was assessed using three items adapted from the questionnaire based on the Multi-Process Action Control framework applied to individual physical activity. Items assessed participants' perceived opportunity to comply with healthy time allocation of 24-hour movement behaviours over the subsequent week (e.g., "If I really wanted to comply with healthy time allocation of 24-hour movement behaviours over the next week, I would have the opportunity to do so"). Responses were recorded on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). A mean score was calculated across the three items, with higher scores indicating greater perceived opportunity.

Planning was assessed using six items adapted from questionnaires based on the Health Action Process Approach. Items assessed participants' use of planning strategies related to compliance with healthy time allocation of 24-hour movement behaviours over the previous week (e.g., "I made regular plans concerning how to comply with healthy time allocation of 24-hour movement behaviours in the last week"). Responses were recorded on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). A mean score was calculated across the six items, with higher scores indicating greater use of planning strategies.

Self-monitoring was assessed using three items adapted from questionnaires based on the Health Action Process Approach. Items assessed participants' engagement in monitoring their time allocation of 24-hour movement behaviours over the previous week (e.g., "I kept track of my time allocation of 24-hour movement behaviours in a diary or log over the last week"). Responses were recorded on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). A mean score was calculated across the three items, with higher scores indicating greater use of self-monitoring strategies.

Identity was assessed using four items adapted from the Exercise Identity Scale. Items assessed the extent to which engagement in healthy time allocation of 24-hour movement behaviours was integrated into participants' self-concept (e.g., "When I describe myself to others, I usually include my involvement in healthy time allocation of 24-hour movement behaviours"). Responses were recorded on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). A mean score was calculated across the four items, with higher scores indicating stronger identity integration.

Habit strength was assessed using twelve items adapted from the Self-Report Habit Index. Participants responded to a common stem ("In the last month, compliance with healthy time allocation of 24-hour movement behaviours was …"), followed by items assessing behavioural automaticity and repetition (e.g., "… something I do frequently"). Responses were recorded on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree). A mean score was calculated across the twelve items, with higher scores indicating stronger habit strength.