Physical Fitness in Czech Preschool Children: Age-Related Trends Assessed Using the PREFIT Battery

Background: Physical fitness is an important marker of health and development during early childhood. However, data describing fitness characteristics of preschool children from Central and Eastern Europe remain limited. This study examined age-related trends, sex differences, and associations with BMI-for-age z-scores (BMI SDS) in selected components of the PREFIT battery in Czech preschool children. Methods: A cross-sectional study was conducted in 40 children aged 3–6 years (19 girls and 21 boys) attending a public kindergarten in the Czech Republic. Physical fitness was assessed using four selected PREFIT components: handgrip strength, standing long jump, 4 × 10 m shuttle run, and one-leg stance. Associations with age, sex, and BMI SDS were analyzed using linear regression models. Results: Physical fitness was significantly associated with age across all assessed components (all p < 0.001). Sex differences were generally small, although boys demonstrated moderately higher handgrip strength than girls. After adjustment for age and sex, higher BMI SDS was associated with lower handgrip strength, poorer standing long-jump performance, and longer shuttle-run times, whereas no significant association was observed for one-leg stance performance. Conclusions: Selected PREFIT components were successfully implemented in a real-world kindergarten setting and were sensitive to age-related differences in physical fitness. Age showed the strongest and most consistent associations with fitness performance, while BMI SDS was independently associated with selected fitness outcomes. Larger multi-site and longitudinal studies are needed to establish population-specific reference values and to clarify the role of early physical fitness in later health and development.