Actilife software

Tri-axial ActiGraph wGT3X-BT accelerometers (ActiGraph LLC, Pensacola, FL, USA) were used to assess PA, SB with standard device initialization (sample rate of 60 Hz, 10 s epochs, and normal filter option). In this study, every participant was asked to wear the accelerometer on the dominant wrist for 7 consecutive days except during water activities (e.g., swimming and showering). On day 8 of the survey, the staff retrieved the accelerometers and downloaded the data using the latest version of ActiLife software (version 6.0; ActiGraph, Pensacola, FL, USA). Freedson’s Adult VM3 (2011) [28 (link)] cut-off points were used to determine PA at different intensities: light: 0–2690 counts per minute (CPM); moderate: 2691–6166 CPM; vigorous: 6167–9642 CPM; and very vigorous: 9643+ CPM; sedentary behaviour < 100 CPM. Non-wear periods were identified as 60 consecutive minutes with no movement data (0 counts).

Students completed the motivation questionnaires and the leisure-time PA questionnaire during one scheduled classroom lesson. Research assistants then demonstrated the correct positioning of an accelerometer and requested that students wear the device for the following seven-days. Students received a text message reminder each morning to encourage them to wear the device. During this period, participants also completed the 48-h travel diary during two scheduled lessons 2 days apart.
To prepare the accelerometer data, we created wear-time files consisting of a count-value for each 1-s epoch of data, excluding periods of ≥60 min of consecutive zero counts, allowing for a 1–2 min spike tolerance of 0–100 counts per minute [39 (link)]. We then used ActiLife software (Actigraph, LLC, Fort Walton Beach, FL) to specify the time periods to be analyzed for each participant (i.e., leisure-time and active travel). The active travel data period was defined by each student’s self-reported recall travel times, and the leisure-time data consisted of all wear-time counts, minus the school day (defined by school bells) and the active travel period. Within each domain, we categorized each epoch count-value based on the intensity of raw acceleration into its corresponding intensity of PA (i.e., sedentary, light, moderate, or vigorous) based on Evenson and colleagues’ equations [40 (link)].

Physical activity was measured using an Actigraph GT3X model (Actigraph LLC, Pensacola, FL, USA) accelerometer. The monitor was worn on the hip with a belt for a seven-day period by the participants, who were requested to remove it only for sleeping and bathing. The recorded data files were downloaded and processed using Actilife software (version 6, Actigraph, 2012). Only days on which the monitors were worn for 10 or more hours were considered valid, and at least three days of data were required to validate the recorded data [40 (link)]. Steps per day were recorded, along with the number of minutes per day spent in intensity-specific categories. The physical activity was classified according to the classification developed by Freedson [41 (link)] as light (100–1951 counts per minute (CPM)), moderate (1952–5724 CPM), or vigorous (>5725 CPM). Moderate-to-vigorous physical activity (MVPA) was defined as the sum of minutes spent in moderate and vigorous physical activities (≥1952 CPM).

Physical activity and sedentary time were measured using a triaxial wGT3X-BT accelerometer (ActiGraph LLC., Pensacola, FL, USA), a small device (3.3 × 4.6 × 1.5 cm; 19 g) with a dynamic range of ± 8 g. Sampling frequency was set to 100 Hz. Accelerometers were worn on an elastic belt at the right anterior axillary line for 7 consecutive days during waking hours except for water-based activities. Non-wear time (60 consecutive minutes of 0 counts^{106 (link),107} ) was excluded from the analyses. Only participants with ≥ 4 days of ≥ 10 h of wear time were included^{104 ,108} . Acceleration signal was converted into vertical axis counts over 60 s epochs and time (min/day) spent sedentary (< 100 CPM^{109 (link)}) and in MVPA (≥ 2,020 CPM¹¹⁰ ) was calculated using ActiLife software (version 6.13.3; ActiGraph LLC., Pensacola, FL, USA).

Time, intensity, and frequency of physical activity engagement will be assessed using ActiGraph GT9X accelerometers (ActiGraph Pensacola, USA) at pre-intervention (with aims to provide baseline comparisons), during the intervention (mid-way, approximately 8 weeks of intervention), and post-intervention (after 16 weeks). The ActiGraph GT9X is a small, light-weight accelerometer (19 g; 4.6 cm × 3.3 cm × 1.5 cm) capable of recording accelerations in the vertical (Y), horizontal right-left (X), and horizontal front-back (Z) axes to compute vector magnitude [VM = √(axisY² + axisX² + axisZ²)]. The ActiGraph GT9X records accelerations over pre-defined time periods (“epochs”). Following which, Actilife software (ActiGraph Pensacola, USA) is used to convert raw acceleration data into “activity counts” for analysis. In this study, the GT9X+ will be initialized to record accelerations in 60-s epochs over a period of 7 days at each assessment time point. During this 7 days, participants will be asked to wear the GT9X attached to an adjustable elastic belt on their right hip in a vertical position [90 , 91 (link)], and to remove the device only for sleeping and water-based activities (e.g., swimming, bathing).