**4. Discussion**

This systematic review and meta-analysis aggregated studies from Asia (China [38–43], Iran [46], Indonesia [47,48], Korean [52], Myanmar [53], Japan [51] and Singapore [59]), Africa (South Africa [60,61]), Europe (Belgium [29], Britain [35–37], Croatia [44], Germany [45], Ireland [49,50], Poland [54,55] and Portugal [56,57]), North America (the United States (US) [29,62–65] and Puerto Rico), Oceania (Australia [28]) and South America (Brazil [30–34]) and demonstrated gender differences in FMS proficiency in children aged 3–6 years. Combined results show that boys are more proficient than girls in total FMS proficiency. From the two dimensions of proficiency in locomotor skills and in object control skills, marginally significant differences were found favoring girls, and significant differences were found favoring boys in object control skills.

Differences in proficiency in object control skills between boys and girls seem to take some cues from biology. A study reported that boys are more likely to use finely segmented pelvic–torso–shoulder rotation when throwing [66]. Young explained the differences in human throwing and hitting behavior from an evolutionary perspective. Early humans made a living by throwing stones and swinging clubs. Women invested more resources into reproduction, and men were more likely to be hunters and warriors. These kinds of patterns are inherited through natural selection [67]. A previous study speculates that mature throwing is more likely an innate skill whose development is biologically determined and somewhat difficult to be influenced by nurture, and the same may be true of striking [68]. Sociological factors and behavior habits may also contribute to gender differences in proficiency in object control. Physical education programs are important for the development of FMS in preschoolers. Research shows that structured physical activity lessons can improve children's FMS [69]. A meta-analysis shows that three or more teacher-led physical activity sessions per week significantly improved FMS [11]. Furthermore, studies have shown a correlation between FMS proficiency and physical activity levels in children. A study using TGMD-2 and accelerometers measured data on FMS and physical activity in kindergarteners and found a positive relationship between object control skills and moderate-intensity physical activity (MVPA) [70]. However, it has been shown that girls are significantly less likely to participate in physical activity than boys during the preschool years, especially at moderate to high intensity [71]. A systematic review including 10,316 children aged 3–6 years (5236 boys and 5080 girls) demonstrated that boys were more physically active than girls [72]. A survey in Norway showed that among children aged 3–4, only 32% of girls and 67% of boys were able to achieve the recommended 60 min of moderate to vigorous physical activity per day [73]. Therefore, different levels of physical activity may be responsible for the gender differences in object control scores. In addition, differences in exercise content may also contribute to gender differences in object control. A cross-sectional study from Japan showed that 5 year-old boys had significantly higher raw scores in terms of object control than girls of the same age (37.8 ± 6.24 vs. 34.5 ± 6.62, respectively), which is consistent with our findings, and the difference is mainly reflected in hitting, kicking and throwing [51]. A study in Australia showed that girls opted for dance and aerobic exercises far more often than boys [74]. A study found that Taiwanese girls prefer to play hopscotch, balance beam and house, while boys prefer ball games and slapstick games [75]. Previous studies have indicated that girls tend to lack opportunities to practice ball games, while boys generally spend more time participating in these games [76,77], which may also be related to parental educational attitudes [78]. In addition, an interesting study in Canada showed that 5 year-old girls' perception of physical ability was related to their proficiency in locomotor skills, but not to object control skills, which may be because girls do not value object control skills [79].

Object control skills are more important than locomotor skills in childhood and continue to affect adolescence [44]. Evidence shows that gender disparities are reduced if girls have the same opportunities for mentoring, feedback, practice and encouragement [64]. Our meta-regression analysis revealed that age was the main factor influencing differences in proficiency in object control skills between boys and girls. Using subgroup analysis to further explore the effect of age, we found that gender differences in children's proficiency in object control skill tend to be significant at age 3, and the advantage tends to favor boys. The difference is significant at the age of 4, and the advantage of boys begins to gradually increase with age, reaching a maximum at the age of 6. We recommend that parents and teachers should start paying attention to children's movements when they are 3 years old and consciously guide children's sports participation types; in particular, girls are encouraged to participate in ball games. Scholars should comprehensively consider the growth and development patterns, types of exercise and professional guidance of boys and girls when studying FMS guidance plans for children.

This meta-analysis provides evidence for gender differences in FMS proficiency in children aged 3–6 years, but some limitations should be considered. First, there are fewer articles and a smaller sample size for children aged 3 and 4 years, which requires more data to confirm. Second, our study only included children aged 3–6 years, and gender differences in FMS in children of other ages are also an important topic. Third, due to the limited number of articles, the study could not be specific to each item in the TGMD subscale (e.g., running, jumping, dribbling, etc.). Studies on specific TGMD items will therefore also be an interesting and useful topic as the number of high-quality studies increases. Finally, because TGMD is the most common tool for measuring FMS proficiency in educational, clinical and research settings, our study only included articles using TGMD or any modified version (TGMD-2 or TGMD-3), but this may have led to inconsistent results. Currently, assessments of children's FMS competencies are primarily conducted through process-oriented and product-oriented approaches. TGMD is a process-oriented assessment that examines children's motor performance on locomotor and object control tasks. We suggest that future research use product-oriented tools to further explore the gendered characteristics of FMS proficiency in young children.
