Clinical Research Directory

Inclusion Criteria 50 healthy boys aged 13-15 (born between 2011 and 2013) who: * are training in football for at least 2 years; * have a valid medical clearance to practice football, * nave an active membership in the MTS Rybnik Football Academy, * have parental/caregiver consent for the participation in the study, * give an informed consent to participate in the study, * did not participate in respiratory or other breathing training over the past year, * are attending the training sessions during the 6 months prior to the study at a level of at least 80% of scheduled hours. Exclusion Criteria: * no valid medical clearance to practice football, * currently occurring acute (including respiratory infections) or chronic diseases that may affect sport endurance and safety of training, * musculoskeletal injuries requiring treatment or limiting participation in football training, sustained within the 6 months prior to participation in the study, * illnesses requiring hospitalization within the 6 months prior to participation in the study, * neurological or musculoskeletal conditions requiring physiotherapy within the 6 months prior to participation in the study, * diagnosed respiratory diseases (e.g., pharmacologically uncontrolled asthma), cardiovascular diseases, or other conditions constituting a contraindication to sports and physical exertion, * contraindications to performing breathing and respiratory exercises, such as: a tendency toward hyperventilation, dizziness during breathing exercises, or recent chest injuries.