2.1. Participants and Procedures
respiratory diseases or dysfunctions, injuries
To calculate the required sample size, G*power was used, thus revealing the need of a total of 288 participants (The study was conducted in accordance with the Helsinki Declaration and the European Union recommendations for Good Clinical Practice (document 111/3976/88, July 1990). The University’s Research Ethics Committee approved the study (N.1/2021). Before data collection, all physical education (PE) teachers and research assistants received training on the testing and evaluation protocols.A sample of 310 children (139 boys vs. 171 girls), aged between 8 and 10 years (9.82 ± 0.51), was selected from schools which in three cities with a similar socioeconomic status and schools that have not previous participated in health promotion programs. The schools were public schools, with attendance from 8:00 to 13:00.All of the children were healthy and free of any disabilities, musculoskeletal, cardiological, neurological, or respiratory diseases or dysfunctions, or any other conditions limiting their ability to perform exercise and able to abstain from all physical activity outside the parameters of the study protocol during the test days. More specifically, the participants did not undertake new sports competitions or modifications to physical activities already practiced before this study and for those who already practiced sports outside of school, the collaboration of their respective coaches was requested in order not to vary the workload.Children were excluded from the data analysis if they did not complete the tests, or did not complete the questionnaire, due to accidents, injuries, or illness. Accordingly, 15 students were excluded from the final data analysis (