Associations Among Diet Quality, Motor Competence, and Physical Fitness in Preschool Children: A Cross-Sectional Study

Background/Objectives: Diet quality, motor competence, and physical fitness are important domains of child development, yet their interrelationships during the preschool years remain insufficiently understood. This study examined whether diet quality was independently associated with motor competence and physical fitness and explored the potential role of motor competence and postural stability within these relationships in preschool children. Methods: A cross-sectional study was conducted in 134 preschool children aged 4–6 years. Motor competence was assessed using selected tasks from the Movement Assessment Battery for Children-2, and physical fitness was evaluated using tests from the PREFIT battery and the sit-and-reach test. Diet quality was estimated using a food frequency questionnaire from which a Diet Quality Index (DQI) was derived. Multiple linear regression models adjusted for age, sex, and body mass index were used to examine the associations among study variables. Exploratory pathway analyses and prespecified sensitivity analyses were additionally performed. Results: Diet quality showed a positive but non-significant association with motor competence, whereas no significant direct association with physical fitness was observed after adjustment for age, sex, and body mass index. Exploratory pathway analyses likewise did not provide evidence of statistically significant indirect associations between diet quality and physical fitness through motor competence, although the direction of the observed associations was consistent across sensitivity analyses. In addition, higher Global Motor Competence and Postural Stability were consistently associated with better global physical fitness, lower-limb muscular strength, cardiorespiratory fitness, flexibility, and speed/agility. Conclusions: The present study found no evidence of significant direct or indirect associations between diet quality and physical fitness after multivariable adjustment, although healthier dietary patterns showed consistently favorable trends. Consistent with previous evidence, motor competence, particularly postural stability, was positively associated with multiple components of physical fitness.