Research design
This is a cross-sectional study investigating the physical activity (PA) and sedentary behavior (SB) patterns of Tibetan and Han adolescents aged 12-18 years in Lhasa,Xizang Autonomous Region. Objective measurements were used to assess these behaviors, and ethnic differences between Tibetan and Han adolescents were compared.
Participants
Figure 1 shows the process diagram for participant inclusion and exclusion. This study was conducted in Lhasa from June to December 2020. Convenience sampling selected the Eighth Middle School of Lhasa and Lhasa Middle School as study sites. A random cluster sampling method then randomly selected several classes of Tibetan and Han students from each grade to recruit participants. Considering the approximately 3:1 ratio of Tibetan to Han students in these schools, three Tibetan classes and two Han classes (with fewer students) were randomly selected from each grade to prevent sample size imbalance.
(Fig. 1) Participant Inclusion and Exclusion Process Diagram
The inclusion criteria were: enrollment in junior or senior high school; age between 12 and 18 years; good health with no physical disabilities; and voluntary participation with written informed consent provided by parents. Participants received accelerometers and questionnaires to assess daily PA, SB, and socioeconomic status (SES). Anthropometric measurements were also recorded.
A total of 1,275 students were initially recruited. After validity checks of the accelerometer data, 19 participants with invalid data were excluded, resulting in a final sample of 1,256 students: 485 Tibetan boys, 465 Tibetan girls, 154 Han Chinese boys, and 152 Han Chinese girls.Dr. Sun Yi oversaw the management and quality control of accelerometer data.
Measures
PA and SB measurement
PA and SB were objectively assessed using ActiGraph GT3X + triaxial accelerometers (ActiGraph, Pensacola, FL, USA). Participants were instructed to wear the device continuously for seven consecutive days (five school days and two weekend days), removing it only for sleeping, swimming, and bathing. The accelerometer was positioned on the right hip, with data collected in 5-second epochs. Data collection began at 9:00 AM on the day of distribution and ended at 9:00 AM on the seventh day, after which all devices were retrieved by the investigators. raw data were downloaded and processed using ActiLife software (version 6.10.2).
Data were deemed valid if they met the following criteria: (1) a minimum of two valid weekdays and one valid weekend day; and (2) at least 600 min of wear time per day [19].
The Evenson cut-point classification method [20] was applied to categorize activity intensity levels.
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