An ecological dynamics approach to promote physical literacy and well-being of primary school children: a cluster randomised controlled trial study protocol


Sedentary behaviour (SB) is defined as any low levels of energy expenditure, including sitting, lying and reclining and expending <1.5 metabolic equivalents,1 which became a prevalent issue in modern society due to advances in technology and environmental changes over the last few decades. For children attending schools, sitting is a more prevalent behaviour as they tend to sit in class for almost the whole day except for PE lessons and break. Clemes et al
2 revealed that children spent up to 65% of their waking time sitting, with some children having reported sitting time of over 10 hour/day.2 Particularly during the COVID-19 outbreak, younger generations in Hong Kong had a significant decline in physical activity (PA) with a corresponding increase in sedentary lifestyle.3 High levels of SB showed positive associations with cardiometabolic health risk such as obesity, blood pressure, cholesterol and insulin in the child population.4 A systematic review and meta-analysis synthesised that there were positive relationships between PA and night’s sleep duration in children and youth.5 More importantly, sedentary lifestyle could be tracked throughout childhood into adolescence and adulthood.6 Therefore, breaking up prolonged sitting patterns and fostering an active lifestyle during childhood can be crucial for promoting a healthy life journey in adulthood. Physical literacy, described as the motivation, confidence, physical competence, knowledge and understanding to value and take responsibility for engaging in physical activities for life,7 a novel perspective for addressing the prevalent SB and declining levels of physical activity (PA) observed among primary school children in Hong Kong, given its established positive correlation with PA levels among adolescents in the region.8 A physically literate individual tends to be motivated to regularly participate in PA, holds positive attitudes towards PA and includes it in their daily living.7 9 The development of physical literacy is, therefore, critical to long-term health and mitigate the adverse consequences of SB.10

The school environment is an ideal setting for conducting PA interventions. A review of 26 studies found that school-based PA interventions have positive effects for the duration of PA, television viewing time, cardiorespiratory fitness (CF) and blood cholesterol levels.11 It has been suggested that schools should provide children with >30 min of moderate to vigorous PA accumulated within the school day.12 13 The application of sit–stand desk in school setting is an ideal approach to increase PA level and decrease SB, as studies have shown the acceptability and feasibility of applying sit–stand desks for primary school classrooms in less than 12 weeks.2 14 15 Specifically, studies have reported that there are benefits to children in reducing their sitting time and increasing PA engagement and academic achievement.16 17 Other research has demonstrated that sit–stand desks in classrooms are effective in improving energy expenditure,18 19 standing time,15 and musculoskeletal comfort for using the desks was also acceptable for children.17 20 However, to provide an active environment for children, such as combining PA recess with sit–stand desks in classroom would be a better approach to increase children’s engagement in PA. Unfortunately, neither sit–stand desks nor PA recess together with daytime sleepiness large-scale intervention studies have been conducted in Hong Kong primary schools.

Therefore, this proposed study seeks to fill this research gap by implementing an ecological dynamics intervention (EDI) that incorporates sit–stand desks in classrooms, PA recess and daytime sleepiness to reduce SB and promote physical literacy and well-being among primary school children in Hong Kong.

We hypothesise that after the intervention and follow-up:

  1. The increase in physical competence including aerobic fitness and motor skills of participants in the intervention group will be greater than their counterparts in the control group.

  2. The increase in PA engagement levels of participants in the intervention group will be greater than their counterparts in the control group.

  3. The increase of cognitive functions of participants in the intervention group will be greater than their counterparts in the control group.

  4. The increase in self-reported sleep quality, physical literacy and quality of life of participants in the intervention group will be greater than their counterparts in the control group.


Study design

A four-arm (cluster) randomised controlled trial to investigate the effectiveness of an EDI on physical literacy and well-being among primary school children in Hong Kong. A total of 1800 senior primary school children (grade 4) across all 18 administrative districts in Hong Kong will be recruited in this study and randomly assigned to one of the following groups (EDI-A: 30 sit–stand tables+PA recess+20 min afternoon nap; EDI-B: PA recess+afternoon nap; EDI-C: afternoon nap only, and a wait-list controlled (WC) group: this group of participants will receive the same intervention as those in the experimental group at a later time). The intervention will be carried out for 6 months with a 3-month follow-up, and data measurements will be taken at four time points (pretest, halfway after 3 months, post-test, 3 months follow-up) with a 3-month intervention. The flow diagram of the study is shown in online supplemental material 1). This protocol adheres to the Standard Protocol Items: Recommendations for Interventional Trials guidelines21 and has been registered on the ISRCTN Registry (ISRCTN 84025914, summarised in table 1).

Supplemental material

Table 1

Registration information


Sample size calculation

The required sample size is calculated based on the hypothesised effect sizes, and the likely rates of participant drop-out for the outcomes. The estimated sample size in each group is 20 concerning the effect size of 0.25, α of 0.05 and power of 0.80.22 With the anticipation of a 20% participant drop-out rate, this leads to a required number of 25 participants per group. Since this is a four-armed randomised controlled trial with at least 18 primary schools representing different administrative districts in Hong Kong, there will be in total (18×4×25) 1800 primary school children participating in this proposed study.

Eligibility criteria and recruitment

Eligibility criteria for participation in the intervention include students without any disability that prevents periods of standing nor an injury/illness that limits performing normal daily tasks. Students must be in grade 4 within 18 districts in three different regions (Hong Kong Island, Kowloon and the New Territories) in Hong Kong. The research team will randomly send a series of email messages and invitation letters to primary schools in accordance with their district via a computer-generated randomisation sequence (GraphPad Software) by a statistician who is blinded to the allocation of participating schools. After the primary school principals agree to participate, a leaflet package, which describes the theoretical background, timeframe, main objectives/learning goals, will be delivered to the school staff. The parents or guardians will also receive a package of leaflets with consent forms (online supplemental material 2) to be signed to approve their child’s participation. Then an introductory meeting with teachers or teaching staff will be held to illustrate practical details related to the intervention. A further workshop will be provided to the teachers with instructions for using sit–stand desks and guidelines for instructing physical activities.

Supplemental material

Randomisation, blinding

The research team will randomly send a series of email messages and invitation letters to primary schools in accordance with their district via a computer-generated randomisation sequence (GraphPad Software) by a statistician who is blinded to the allocation of participating schools. Outcome assessors will employ predetermined procedures to evaluate outcomes without prior knowledge of the intervention received by participants. They will not be involved in the implementation process, ensuring their natural blinding throughout the study. However, emergency unblinding will be permitted under specific circumstances crucial for participant safety, such as the occurrence of sudden cardiovascular or muscular diseases requiring knowledge of the participant’s previous PA history for immediate clinical management. The decision to unblind will be at the discretion of the principal investigator (PI) or an authorised individual not directly engaged in outcome assessments.


Participants from different cluster will be randomly assigned to one of the following interventions:

  1. Ecological Dynamics Intervention—A (EDI-A): 30 sit–stand tables will replace the traditional desks for all students to use during the school day. All children in this class are exposed to the sit–stand desks for at least 1 hour/day on average across the week. Students who are exposed to sit–stand desks will be encouraged to break up their classroom sitting every 15 min with standing for at least 2 min. Traditional chairs will be left for children to feel free to sit whenever they want to. During recess each day PA, including a series of mobility, stretching and pulse-raising exercises, will be provided to students. There will also be a 20 min afternoon nap immediately after lunch in each school day.

  2. Ecological Dynamics Intervention—B (EDI-B): in this condition, the focus will be on incorporating PA recess with mobility exercises, stretching and pulse-raising activities during the school day. The implementation of sit–stand desks in classrooms will be deferred in this group, allowing for a comparative assessment of the independent effects of the PA component.

  3. Ecological Dynamics Intervention—C (EDI-C): this condition will only incorporate the afternoon nap component into the school day. An uninterrupted 20 min nap will be provided in classrooms after lunch, promoting a restorative environment and enhancing overall well-being. The introduction of sit–stand desks and PA recess will be deferred, enabling an isolated evaluation of the nap intervention.

  4. Wait List Control (WC): the wait-list control group will not receive any modifications to their study environment during the initial phase. However, they will receive the same comprehensive intervention as the experimental groups later, allowing for a valid comparison of the intervention effects.

Participants may withdraw from the intervention or modify the allocated intervention if they meet specific criteria, such as personal scheduling conflicts, physical discomfort, musculoskeletal disease, cardiovascular disease or inability to adhere to the intervention protocol. To ensure the successful implementation of the intervention, the principal of each participating school will be the key contact person responsible for approving the project and procuring the sit–stand desks. Subject teachers and PE teachers from each class will actively participate in the intervention progress, as they will be responsible for planning the sitting and standing patterns, as well as facilitating daytime sleepiness among the students. Therefore, a detailed instructional meeting will be held for all the teachers to instruct them on how to use the sit–stand desks and sleep pillows, as well as the setup of the PA recess facility and equipment. Additionally, subject teachers will play a vital role in encouraging students to use the sit–stand desks to break up their classroom sitting with standing intervals, while PE teachers will lead the PA recess exercises. Meanwhile, regular contact with the schoolteachers and parents (eg, once a week) via email will be used to improve adherence. An excel file will be used to record the adherence of the participants every month.

Data collection

In this proposal, we will adopt both objective measures and self-reported measures to cover the elements and domains of physical literacy and well-being. Participants will be evaluated at pretest, halfway after 3 months, post-test, 3 months follow-up. All of them will be conducted at the participants’ primary school in Hong Kong. The self-reported measurements will be administered by research assistants while the objective measurements will be performed by certified physical fitness instructors and health professionals.

Objective measures

Physical competence

CF will be measured using the Progressive Aerobic Cardiovascular Endurance Run (PACER). The PACER comprises a multistage progressive 15 m shuttle run requiring participants to run laps between 2 markers in time (decreases each minute) with prerecorded audible beeps. Participants run laps until they are unable to finish before the beep on two separate occasions. Participants’ CF status is based on the number of laps completed. PACER has a strong correlation with maximum oxygen consumption (r=0.83).23

Fundamental movement skills (FMS) The Canadian Agility and Movement Skill Assessment (CAMSA) will be adopted to measure children’s FMS. Catching, throwing, skipping, hopping and kicking will be assessed children’s FMS. The score of the CAMSA test is composed of time score (14 points) and skill score (14 points), resulting in a total of 28 points.24

Daily behaviour (PA)

Accelerometer (Actigraph GT3X+) will be used to measure the PA engagement levels of participants and are categorised as sedentary, light, moderate and vigorous. Participants will wear accelerometers to measure their PA engagement levels for at least 8 hours per day, for seven consecutive days.

Cognitive function

Cognitive domains to be assessed contain sustained attention, distractibility and working memory. The psychomotor vigilance task (PVT) test, AX Continuous Performance Task (AX-CPT) and N-back test will be used for evaluating children’s cognitive functioning. These tests will be performed using Psych lab 101 App in the iPad platform. The PVT-type test25 is a sustained-attention, reaction-timed task that measures the speed with which subjects respond to a visual stimulus. The participant needs to press a button as soon as the light appears. Reaction time will be calculated. AX-CPT26 is any of several kinds of neuropsychological test that measures a person’s sustained and selective attention. This test asks participants to press a button when seeing a red ‘A’ followed by ‘X’. Reaction time and corrections will be calculated. The N-back test is a continuous performance task that is commonly used as an assessment in cognitive neuroscience to measure a part of working memory and working memory capacity.27 The participant is presented with a sequence of stimuli, and the task consists of indicating when the current stimulus matches the one from n steps earlier in the sequence.

Self-report measures

Physical literacy

Perceived Physical Literacy Instrument (PPLI). It is a 9-item instrument consisting of subscales—‘knowledge and understanding’, ‘self-expression and communication with others’ and ‘sense of self and self-confidence’ were identified as key attributes of physical literacy.7 PPLI is used to measure the perceived physical literacy of different individuals.28 Participants responded to the instrument on a 1 to 5 Likert scale (1=strongly disagree and 5=strongly agree). Sum et al
29 confirmed that the three-factor validity (Root Mean Square Error of Approximation (RMSEA)=0.08; Comparative Fit Index (CFI)=0.94; and tandardized Root Mean Square Residual (SRMR)=0.04) and convergent validity (CR=0.72–0.78; AVE=0.43–0.54) of the PPLI-A was satisfactory.29

Quality of life

Health-related quality of life will be assessed using the Child Health Utility 9-Dimensions (CHU9D)30 which includes nine items (worried, sad, pain, tired, annoyed, schoolwork, sleep, daily routine, and activities), and each item is scored on a five-point scale. CHU9D is a generic preference-based measure of health-related quality of life developed for children aged 7–11 years.

Sleep quality

Pediatric Daytime Sleepiness Scale (PDSS)31 is a parent-reported instrument consisting of 8 items, having >0.40 acceptable factor loadings. Higher scores on PDSS were associated with reduced total sleep time, poorer school achievement, poorer anger control and frequent illness. Internal consistency of the total 8-item scale (factor 1, PDSS) was α=0.81/0.80 for the split-half samples.

Data analysis

Descriptive statistics (means and SD) for primary school children’s physical competence, PA levels, cognitive function, physical literacy, quality of life and sleep quality will be calculated for all subscales across all instruments. One-way analyses of variance (ANOVAs) will be used to test for differences in the baseline characteristics of participants between groups. Repeated measure ANOVAs and MANCOVA, with time (baseline, after intervention and follow-up) as within-subjects factor, and intervention group as between-subjects factors, will be used to evaluate the effects of different interventions on the students’ physical literacy and well-being. A Bonferonni correction to the p value will be calculated to adjust for multiple tests. SPSS V.27 for Windows will be used for data analysis. Statistical significance will be set at a level of 0.05.


During the study, personal data will be treated with the utmost confidentiality and privacy. Participants’ informed consent will be obtained, and data will be anonymised using unique identifiers. Secure data collection methods, including encryption and limited access, will be implemented. Data will be retained for 5 years, and personal identifiers will be securely disposed of when no longer needed. Access to personal data during the study will be limited to authorised research team members, including the PI, coinvestigators, data managers and other staff involved in data-related activities. For those outside the research team who wish to access the study data, permission must be sought from the principal investigator. Following permission and the completion of signed confidential documentation, access to the data will be granted.

Data monitoring

Interim analyses will be conducted at predetermined intervals to assess the efficacy and safety of the trial interventions. These analyses will be performed by a statistician who is blinded to the data input, ensuring objectivity and minimising bias. If the statistician identifies issues with the study efficacy (eg, lack of efficiency) or potential safety concerns, they will promptly report these findings to the study PI. The PI will then carefully evaluate the situation and make the final decision regarding whether to terminate the trial or continue based on the interim analysis results and other relevant considerations.32

Patient and public involvement

Patients or the public WERE involved in the design, or conduct, or reporting, or dissemination plans of our research.

Protocol amendments

We will communicate any protocol modifications, such as changes to eligibility criteria, outcomes or interventions, to the Joint CUHK-NTEC Clinical Research Ethics Committee in Hong Kong, trial participants, and trial registries via email after discussion with the PI.


To prioritise participant safety and maintain the trial’s integrity, we have implemented a structured approach. Data collection will occur at three month intervals, encompassing adverse events. Primary school teachers will assume responsibility for collecting, assessing and reporting adverse events and unintended effects of trial interventions to the PI. Recorded events will be documented in a predetermined Excel file for future reference. In the event of such occurrences, healthcare professionals will be promptly summoned for assistance.

Ethics and dissemination

This study will adhere to the ethical principles outlined in the Declaration of Helsinki33 and the principles of Good Clinical Practice as outlined in the International Conference on Harmonisation (ICH) guidelines, specifically ICH E6(R2).34 Ethical approval has been sought from the Joint CUHK-NTEC Clinical Research Ethics Committee (CREC Ref.No.:2024.027). The finding of this study will be disseminated via peer-reviewed journals, international conference presentations and academic lectures. For secondary analysis of the data, please contact the corresponding author for permission.

Research Timeline

The proposed study consists of three phases (staffing and programming, research arrangement and reporting), each phase comprises of several sequential steps, with detailed procedures and time allocations delineated in online supplemental material 3.

Supplemental material

Trial status

We will initialise the study on 1 January 2024 and will be completed on 30 June 2026.

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