Quantitative study with the aim of linking the academic performance of students who are high-level athletes in Catalonia (Spain) and who do not have any institutional support (high-performance centre, reduction of subjects, etc.) or belong to any educational institution with adapted curriculum (90-95% of households), compared to sedentary students who play sports only occasionally. The study divided students into two groups by age: 12, 14, 16 and 18 years old (secondary school). The general group (GG) was made up of students who did sports at school, did not participate in major competitions, and the weekly training requirement did not exceed 3 hours (N = 262). The group of athletes (AG) is made up of students who at least competed for the Championship of Catalonia (swimming and basketball) and the weekly training requirement exceeded 4.30 in younger students (N = 212). The questionnaires were constructed in order to gather academic information, highlighting the grades of the subjects for the second evaluation of the 2008-09 academic year and full-time sports data for training (day session, hours, competition) and schooling (public or private). We found a significant correlation (0.99) in comparing the evolution of differences between the grades of the groups. Supporting an extraordinary demand for training, and increasing with age, student athletes have better academic performance throughout secondary education. However, this trend is broken in high school, coinciding with the highest dedication to training. Two other important considerations are highlighted in the study: first, the GG presented inactivity levels which increase linearly with age and this is more prominent in females, and secondly, the enrolment of the school is basically AD private state-assisted and not public system, which can make us think about whether the family ideology also influences the sports options for children