Understanding Health in Spanish Children: The Role of Demographics in Physical Activity and Nutrition Attitudes.

: This study investigates the influence of sex, age, and their interaction on health behaviors, perceived physical fitness, and attitudes toward physical activity and eating among schoolchildren. : A cross-sectional analysis was conducted on 1027 students aged 8-12 years from 15 primary schools in Lleida. Participants completed the PAQ-A for physical activity, the IFIS for perceived physical fitness, the AATPA for attitudes toward physical activity, and the AATE for attitudes toward eating. Data were analyzed using regression models to assess the effects of sex, age, and their interaction. : Males reported higher physical activity levels and more positive attitudes toward physical activity than females ( < 0.05). Perceived physical fitness was also greater among males ( < 0.05). Age was positively associated with physical activity and attitudes toward healthy eating, with older children reporting more favorable outcomes ( < 0.01). Significant interaction effects between sex and age were observed for physical activity levels and attitudes toward eating, indicating demographic-specific trends. : This study highlights significant sex and age differences in children's health behaviors and attitudes. These findings underscore the need for gender-sensitive and age-appropriate interventions to promote healthier lifestyles among schoolchildren. Future research should explore longitudinal designs to confirm these relationships over time.