Exploring Self-Reported Physical Activity Levels and Physical Fitness in Italian Children: A Mediation and Moderation Analysis

Background/Objectives: Skill-related physical fitness is a crucial factor influencing health status during childhood. Starting from the lack of knowledge in the field of skill-related physical fitness and levels of physical activity in Southern Italy, this cross-sectional study aims to explore the mediating and moderating influence of PAL on the association between BMI and skill-related physical fitness. Methods: The sample (N = 387 students; male = 196, age = 12.2 ± 0.87 yrs; female = 191, age = 12.3 ± 0.93) was recruited from schools in the Apulia Region. The assessment included standing long jump (SLJ), 2 kg medicine ball throw (MBT) and 10 × 5 shuttle run (10 × 5) as indicators of physical fitness, and a self-report for measuring daily physical activity (PAL). A 2 (gender) × 3 (BMI cutoff)-factorial ANOVA was performed to highlight differences between groups for physical fitness components and PAL. Then, mediation and moderation models were created, establishing BMI as the independent variable, physical fitness tests as dependent variables, and PAL as the mediator and moderator variable. Results: The findings showed higher physical fitness and PAL in male and female normal-weight groups than in those who were overweight and obese. Mediation analysis revealed that higher PAL improved performance in SLJ (b = 0.091, p < 0.01, R² = 17.16%), led to a modest understanding of the variation in MBT (ΔR² = 0.026), and significantly reduced the time spent to perform 10 × 5 (p < 0.0, R² = 10.72%). Conclusions: Despite the obtained results, future research is needed to further understand the association between physical fitness and the sociocultural determinants of physical activity to guide institutional policies and interventions to prevent poor health habits.