Dose-response relationship of weekly physical exercise on fitness of students

Introduction. Childhood obesity and sedentary lifestyles highlight the critical need to understand the impact of physical exercise on fitness. This study investigates the dose-response relationship between weekly exercise volume and physical fitness components in adolescents using Portugal’s FITescola® assessment program. The objective of this study is to evaluate the influence of weekly physical exercise duration (2–8.75 hours) on aerobic capacity, muscular strength, and flexibility in 80 adolescents (aged 13–15) over one academic semester. Methodologies. A cohort of 80 adolescents (56.25% female; 43.75% male) completed FITescola® assessments, including completed FITescola® assessments, including cardiorespiratory endurance, lower-body explosive strength, upper-body muscular endurance, abdominal muscular endurance, and lower-body flexibility. Data were analyzed via ANOVA and Pearson correlations (SPSS v29), controlling for habitual physical activity (tracked via the Portuguese Youth Activity Profile) and socioeconomic factors. Results. Significant dose-dependent improvements were observed with increased exercise volume: Shuttle test: Performance increased from 45.77±5.643 (2hours/week) to 115.2±3.962 (8.75 hours/week; p<.001). Sit-ups: Scores improved from 59.79±4.961 to 69.63±8.021 repetitions (p<.001). Lower-limb flexibility: Progressed from 14.92±3.120 cm to 22.46±3.575 cm (p<.001). Strong correlations emerged between exercise volume and fitness outcomes (r =.817; .981; p<.001). Conclusion. This study confirms a robust dose-response relationship between structured exercise and enhanced physical fitness, supporting its integration into school health policies. Future longitudinal studies and demographically diverse cohorts are needed to generalize findings and address health equity gaps in exercise accessibility