Study design
The “Stand + Move” intervention was designed as a three-arm RCT study to evaluate the effectiveness of the blended “Stand + Move” intervention program. Outcome data are collected at baseline, post-intervention and 3-month follow-up in self-perceptions and objective measures of all variables. Baseline data collection was conducted before the intervention began in the two intervention arms. The post-intervention measure for all the clusters will be performed successively 13-week after the completion of the intervention aiming to reduce children’s SB. The follow-up measurement in all clusters will be performed 3 months after the post-intervention measurement. Baseline data collection took place between September and November 2020. The measurements at post-intervention and follow-up will take place in 2021.
The present study focused on approximately 9-year-old 4th grade students in Hong Kong and the ethical approval was obtained from Survey and Behavioral Research Ethics of the Chinese University of Hong Kong. Clusters were regarded as the classes recruited from one public school located in New Territories, Hong Kong. Following the initial recruitment process, baseline assessments were conducted at participating schools. Prior to their participation, written informed consent were provided by the parents/guardians of all children. All the personal information about potential and enrolled participants were kept confidentially before, during, and after the trial, and only the project members have access to the final trial dataset under the aim of the data analysis. Figure 1 shows a flow chart of this study. The clusters of participants were randomly assigned (using Google random number generator) into one of the following three groups: a single PA break intervention group (PA), a blended intervention group (combining sit-stand desks and PA breaks; SSPA), or a control group (CG). A blended intervention design was adopted, as it was considered an innovative design for disrupting prolonged sitting and improving engagement in PA, a pragmatic measure of school-aged children’s PL (34). In addition, this intervention was regarded as a key facilitator of the Comprehensive School PA Program (CSPAP), a necessary approach for fostering school-aged children to develop their PL, considering that schools play a critical role in reshaping both social and physical environments, as well as providing information, tools, and practical strategies to help students adopt healthy lifestyles (10). Primary outcomes included children’s PA level, including MVPA and sedentary time, and PL level (self-perceptions and actual PL) (35). Secondary outcomes consisted of children’s personal status, such as body weight and height, their performances in executive functions, academic achievement, and changes in sleep patterns and duration. As the current study was led by the teachers who are required to implement the interventions in schools, they were blinded to group allocation. Students were not informed about the research aims and related information, and was therefore blinded to group allocation. Research assistants who are responsible for data collection were not blinded to group allocation.
Participants and recruitment
As previous research reported a significant increase in SB in children aged 11 years and older (32) and reduced the typically observed SB before transition into adolescence, this study recruited students from fourth grade of Hong Kong primary schools (9–10-year-old). G-power software was used to calculate sample size with an alpha of 0.05, power of 80%, and effect size (r) of 0.3 (36). Since a full desk allocation system (a sit-stand desk for every child) guaranteed the optimal health benefits for the children as they could have maximum exposure to the desks, only one school was approached and recruited, with a total number of 81 participants, who was randomly assigned to either of the three conditions with a 1:1:1 ratio (Figure 1). Children were excluded if they: (a) not 4th grade; (b) had a disability that prevented periods of standing; or (c) had an injury or illness that limited performing normal daily tasks.
Consent forms were distributed to all the 4th grade students’ parents by the school teachers. A briefing session on the aims and procedures of the intervention was held for all the teachers and parents, who agreed to participate in the entire intervention process. Participants’ personal data was kept confidential, and was informed that they can voluntarily withdraw from the project at any time, without prejudice. Upon reaching into an agreement with the principals, teachers, and parents, the trained appraisers started data collection after obtaining informed consent.
Baseline measures
Primary outcomes
Physical literacy – actual level
Body mass index (BMI, kg/m2) was calculated from the measured weight (nearest 0.1 kg) and height (nearest 0.1 cm). PL was assessed using the Chinese version of the Canadian Assessment of PL, second edition (CAPL-2, Chinese) (37), a comprehensive protocol that can accurately and reliably assess a broad spectrum of skills and abilities that contribute to and characterize the PL level of a participating child (38). It comprised four domains: Daily Behavior; Physical Competence; Knowledge and Understanding; and Motivation and Confidence. The total achievable score for this assessment was 100 points. Daily Behavior comprised two parts: objectively-measured step counts and self-reported moderate-to-vigorous physical activity (MVPA) (i.e., the number of days in a week that children engaged in activities that made them breathe harder and their heart beat faster). The total achievable score for this assessment was 30 points. Physical Competence consisted of three parts: i) FitnessGram 15 m/20 m Progressive Aerobic Cardiovascular Endurance Run (PACER) (39) for evaluating aerobic fitness; ii) Plank Assessment of Torso Strength (40) for testing musculoskeletal endurance related to back health, the ability to stabilize the body, and the functioning of both the upper and lower limbs; and iii) the Canadian Agility and Movement Skill Assessment (CAMSA) for assessing motor competence (41). The total achievable score for this assessment was 30 points. The Knowledge and Understanding domain assessed a child’s PL-related knowledge, with five questions equaling a total of 10 points. The Motivation and Confidence domain evaluated a child’s confidence in his/her ability to be physically active, as well as his/her motivation to participate in PA. A revised version of the “What’s most like me,” the Children’s Self-perceptions of Adequacy in and Predilection for Physical Activity (CSAPPA) questionnaire (42), was adopted for assessing this domain with a total of 30 points, which was adequately evaluated for model fit after revisiting the concept of PL (43). The whole CAPL-2 (Chinese) model was reported a good fit with construct validity: chi-square (χ2 = 70.16, df = 43, p < 0.05), RMSEA = 0.04, 90% CI (0.024 – 0.062), CFI = 0.94, TLI = 0.90, to be adopted to evaluate children’s PL.
Perceived physical literacy
PL perceptions was assessed using the adolescent version of the Perceived Physical Literacy Instrument (PPLI), a nine-item questionnaire (44). Each response was rated on a 5-point Likert scale ranging from strongly disagree to strongly agree. Adapted from a previous version constructed by PE teachers (45), the current questionnaire’s validity was confirmed through confirmatory factor analysis (CFA): chi-square (χ2 = 321.54, df = 24, p < 0.05), CFI = 0.95, RMSEA = 0.08, and standardized root mean square residual (SRMR) = 0.04. Furthermore, the questionnaire showed acceptable reliability, with α values ranging from 0.68 to 0.76.
Physical activity
Children’s PA was monitored by two different types of activity devices, namely ActiGraph GT3X+ (46) and activPAL™ accelerometers (PAL Technologies, Glasgow, United Kingdom). The ActiGraph monitors were worn on the children’s waists for seven consecutive days. Data was collected in 15 s epochs to account for children’s natural activity levels, which generally occurred in short bouts (47) as it was shown to present the most acceptable classification accuracy for accelerometer use among children. Evenson cut-points (MVPA ≥ 2296 counts min−1) was applied to intensity levels. The ActiGraph monitors had to be worn for at least 8 h/day for a minimum of 4 days, with at least one valid weekend included (48). The accelerometers could be removed only during water activities, such as showering or swimming, and the participants had to fill in the information provided in the log sheets. While the activPAL monitors were worn on the midline of children’s right thighs and it could be used to detect limb positions, such as sitting/lying, standing, and stepping (49). Similar to ActiGraph, a continuous 7-day-wearing waterproof protocol was adhered to ensure the monitoring of children’s PA and SB during a whole 24 h, and the activPAL data was divided into 15-s periods with meeting a minimum requirement of 3 valid weekdays and 1 valid weekend day (50, 51). The activPAL data was summarized into time spent sitting/lying, standing and stepping.
Secondary outcomes
Executive functions
Inhibitory control
EFs, including inhibition, executive control, and planning were assessed by three computer-based tasks, all of which was performed using the Inquisit 5 platform. Participants were required to perform three tasks, one by one, in a quiet room under the supervision of an instructor who was trained prior to the testing. Inhibition control was examined using a modified version of the Eriksen flanker task (52). This task consisted of five arrows on a screen, and participants were asked to determine the direction of the target arrow in the middle. The arrows pointing to the left “<” and right “>” directions required a right and left keyboard button response, respectively. The two flanker arrows on each side of the target arrow worked as the distractors and would appear as either congruent trial “>>>>>” or congruent trial “>><>>.” Each stimulus was shown for 120 milliseconds (ms), and the participants were required to respond within 200 to 1750 ms from the onset of the arrows, for a valid response. This task contained 4 practice trials and 20 test trials, with an equal number of congruent and incongruent trials occurring in a random order. The outcomes included two domains: accuracy (percentage of correct responses) and reaction time (number of ms for correct responses).
Executive control
Executive control was measured with the classical version of the Wisconsin Card Sorting Test (WCST) with the standard number of 128 cards (53). This task consisted of 4 key cards and 128 response cards. Participants were instructed to sort the response cards, shown at the bottom of the screen, according to the characteristics of the key cards presented on the screen’s upper side, comprising the following categories: colors (red, green, yellow, and blue); forms (triangle, star, cross, and circle), and numbers (1-4). The instructor was permitted to provide instructions relating to the categories either prior to or during the task, while feedback on “correct” or “incorrect,” was presented after each selection. It took each participant approximately 20 mins to complete the task. Both total and perseverative errors were recorded as executive control variables, since an increase in any of these variables suggested executive control impairment (54). While the calculation of total errors were based on the number of times participants match a card incorrectly, perseverative errors were based on the participants’ continuing to follow the previous error rule.
Executive planning
The Tower of London Task, a widely administered neuropsychological assessment were used for measuring the planning aspects of EFs (55). The task consisting of a practice trial and 12 test trials required the participants to move beans to solve problems. When presented with a graph on the screen showing three vertical pegs with graded heights and each holding beans (either 3, 2, or 1), the participants had to move the beans so as to be identical to the goal graph, without violating the rules (56). It took each participant approximately 20 mins to complete the task. Both the total correct and total move scores were derived for analysis, given that these variables were found to be influenced by aerobic and resistance exercises (56).
Children’s Sleep
The Children’s Report of Sleep Patterns (CRSP) questionnaire, containing 60 items pertaining to three modules—Sleep Patterns, Sleep Hygiene Index, and Sleep Disturbances Scale—were used to measure different aspects of sleep among children aged 8 to 12 years (57). The questionnaire’s psychometric properties had been tested in a population of 456 children using a multi-method, multi-reporter approach, and are reported to have good reliability and validity. This assessment was administered in the current study. In addition, considering the negative impact of sleep loss on grades and overall daytime functioning in children, daytime sleepiness was assessed using the Pediatric Daytime Sleepiness Scale (PDSS) (58). This was a parent-reported instrument consisting of 8 items, having > 0.40 acceptable factor loadings. Internal consistency of the total 8-item scale (factor 1, PDSS) was α = 0.81/0.80 for the split-half samples.
Data collection procedures
During the first stage of data collection, participants were required to complete both the CAMSA and Plank during the PE class. The participants were divided into two groups, with one or two appraisers per group, and rotated around the stations (one test per station) till the assessment was completed. Prior to CAMSA, they watched two test presentations performed by an appraiser. During the first presentation, the appraiser covered the entire course at a slow pace with detailed verbal descriptions of each skill. While the second presentation was at full speed, the appraiser maintained skill accuracy. Participants were required to practice twice, at full speed, while maintaining their skill accuracy. Each participant’s highest combined time and skill score was recorded as his/her final grade. In the Plank test, the participants watch the demonstrations first. Thereafter, stopwatches were used to record when each participant achieved the right posture. One warning was announced when participants’ positions were too low/high or they were unable to maintain their position. The recording was stopped when participants shifted their positions a second time.
During the second stage of data collection, participants’ aerobic fitness was monitored based on their participation in the PACER 15 m/20 m shuttle run during their scheduled PE classes. Due to limited space, all participants ran from one marker to another set 15 m apart, while keeping pace with a prerecorded Cantonese cadence. The total number of laps achieved by each participant was recorded, and then converted to the standardized 20 m PACER score using the FitnessGram PACER Conversion Chart (39). Lastly, ActiGraph and activPAL accelerometers were distributed to the participants to monitor their step counts, PA and SB for seven consecutive days.
Height and weight measurements, questionnaire completion, and participation in the cognitive tests all took place during music, science, or other classes, and not during the PE classes. Two participants visited the quiet experimental room at a time to complete the aforementioned measurements under the instruction of two trained helpers.
Process evaluation
Process evaluation (often called formative evaluation) aims to improve a policy or program as it was being implemented (59). With regard to feasibility, evaluation should check whether and to what degree the implementation is accomplished, such as context, reach, fidelity, acceptability implementation, impact, acceptability, and sustainability over time through a pragmatic design (60). In the current study, a qualitative methodology will be adopted to examine the perceptions and experiences of key stakeholders in the intervention schools, as the interpretivist paradigm illustrates that human action and interaction, in the school setting, is experienced subjectively evaluated through individual meaning making (61). Key stakeholders, such as teachers and students, are inherently associated with the effectiveness of blended “Stand + Move” intervention. This method will include semi-structured interviews with the teachers involved in the intervention group and focus groups with randomly selected students after measurements to avoid its influence on the results. Besides, classroom observations will also be conducted during the intervention period by research team members, who recorded field notes based on these observations (62), including positive or negative responses to the enforced sit-stand desks utilized during class, the children’s attitude towards sit-stand desks during the class and PA breaks during the recess, and sitting and standing behavior immediately after the enforced sit-stand desks implementation.