Introduction: The assessment of physical fitness is an important indicator of health during the stage of childhood and adolescence and is an excellent predictor of health in adult life. Aim: To monitor the fitness of a group of adolescent students who performed longitudinally physical activity twice a week. Methods: A longitudinal study (Panel) was performed. 93 female adolescents who were in the first year of secondary school (14.49 ± 0.2 years) were evaluated. We evaluated each year during the month of March (2010, 2011, 2012 and 2013). Anthropometric variables (weight and height) and physical tests (flexibility, abdominal strength and endurance horizontal jump) were evaluated. Body Mass Index (BMI) was calculated. Results: The variables weight, height and BMI were kept constant during the 4 years of follow-up, while the variable flexibility remained relatively stable in the first three years, then there was significant at 17 years (p<0.001) decrease. In tests of abdominal strength and vertical jump significant at 16 and 17 in relation to the 14 years (p<0.001) increases were noted, however, aerobic endurance gradually increased at 15, 16 and 17 (p<0.001). Conclusion: After monitoring a sample of adolescent girls for four years of study, it was determined that the practice of physical activity scheduled for twice a week contributes to the improvement and maintenance of the physical fitness of young adolescents.