4. Discussion
RA
Preschool children undergo a period of rapid physical growth and maturation of the nervous system, requiring the development of corresponding physical fitness, such as agility, strength, and reaction speed [In terms of cardiorespiratory fitness, pre-post effect sizes exhibited significant improvements in the 20 m shuttle run test in the BM and RA groups, which is consistent with previous studies [The muscle strength (grip and standing long jump) of preschool children in all intervention groups, including the control group, obviously improved after the interventions, which is consistent with previous research findings [The motor fitness of preschoolers was obviously improved in all intervention groups after the 16-week interventions, and the intervention groups had certain advantages over the CG group. Previous research, and systematic review and meta-analysis also, indicated that the designed physical activity programs had a positive effect on the motor fitness of preschool children [In summary, the MA group had advantages over the BM, RA, and CG groups in terms of the improvement of the physical fitness of preschool children. In addition, in this study, the BM and RA groups had no advantages over the CG group with regard to improvement of cardiorespiratory fitness, musculoskeletal fitness, and motor fitness. These results are similar to those of another study that found that teacher-centered intervention granted preschool children no advantage over the control group in terms of motor fitness [There are several limitations that need to be addressed in this study. The first is in terms of sample representation; because of the scale and difficulty of the experiment, only 4–5-year-old preschoolers were included in this study. Therefore, the results of this study may not be applicable to all preschool children. Second, the baseline level of physical fitness in the experimental groups was not balanced. The improvement after the interventions will be greater if the baseline test level is low. In addition, the physical environments of the baseline test and post-intervention test were relatively different. Therefore, the significance of analyzing the improvement of physical fitness before and after the interventions is limited. However, we used a mixed-effects model to adjust the effect of the baseline test results, gender, and other factors in the intervention effect. In addition, all kindergartens participating in the experiment were in the same community, and the test environment was similar. Finally, the number of preschool children in each group included in the analysis was not balanced, but the minimum sample size that meets the statistical analysis was 30 children per group [