METHODS: This study included three samples of 1,101 secondary school students (12-19 years old). The first sample consisted of 518 participants (50.4% males, 49.6% females) for correlation tests and exploratory factor analysis (EFA). The second sample consisted of 227 participants (55.75% males, 44.24% females) for confirmatory factor analysis (CFA), convergent validity, and sample size invariance tests. The third sample consisted of 356 participants (54.50% male, 45.50% female) for the internal consistency reliability test, invariance test (cross sample size, education level and gender), and t-test.
RESULTS: Pearson correlation analysis of the PAQ-A indicated that all the total-item correlations exceeded 0.2, indicating good consistency across the items. Subsequent EFA of the Chinese version of the PAQ-A revealed a two-factor structure. CFA subsequently validated this structure. One of the items exhibited a standardized loading below 0.4 and was excluded. The exclusion of this item resulted in increased standardized loadings for the remaining items, ranging from 0.40 to 0.82, which indicates improved fit indices. This adjustment underscores the questionnaire's satisfactory convergent validity and robust discriminant validity. The overall Cronbach's alpha was 0.821, with the values for the first and second factors being 0.757 and 0.716, respectively. The questionnaire demonstrated stable invariance across sample sizes and education levels and additionally showed partial scalar invariance across genders. A t-test revealed a significant difference between males and females, which aligns with previous findings. These findings supported the construct validity of the questionnaire.
CONCLUSION: This study validated the Chinese version of the PAQ-A for assessing adolescent PA in China, with a two-factor structure improved by removing one item.
OBJECTIVE: This study aims to review the external and internal load performed by soccer referees in high-level competitions, to identify changes in these indicators over different periods as the competition progresses, and to analyze the standards for dividing speed zones and heart rate zones.
METHODS: Web of Science, PubMed, Scopus, and EBSCOhost were thoroughly searched. Grey literature sources and Google Scholar were also consulted, with a focus on analysing and comparing the physical demands of soccer referees at different phases of high-level matches.
RESULTS: A total of 14 manuscripts were included in this review. Studies revealed that the total distance (TD) covered by referees during a full match ranged from 9 to 12 km. High-intensity running (HIR) constituted 2.0-18.7% of TD, accounting for approximately 38% of total time (TT). Referees reached 80-100% of their maximal heart rate during matches. The standards for dividing speed zones and heart rate zones varied among the selected studies.
DISCUSSION: This systematic review aimed to provide a comprehensive overview of referees' physical demands (e.g., TD, HIR, and HR) to offer practitioners valuable biological data for training and competition preparation. The lack of uniform criteria for dividing speed and heart rate zones limits data collection, thereby affecting the reporting of distances covered at different exercise intensities.