ACE and cystic fibrosis: Based on this, the hypothesis is that CF training increases the expression of ACTN3 and ACE, and the objective is to analyze the expression changes in the ACTN3 and ACE genes due to the training effect in CF athletes, with the specific aims of characterizing a sample of CF athletes from the RX category and determining their ACTN3 (RR, RX, XX) and ACE (DD, II, ID) genotypes, assessing physical fitness, determining the expression of ACTN3 and ACE genes pre- and post-training, and applying and assessing the volume of the training program.