The implication is that the airway damage probably is the result of years of training. High level competitive swimming can put a high oxygen demand on the body leading to abnormally deep, rapid breathing.
Years of hard training may be to blame for the higher than average rates of asthma seen in elite adult swimmers, but a study in the Journal of Allergy and Clinical Immunology concludes the respiratory problems don't seem to be a problem for teenagers. The research compared the competitive swimmers with other adolescents. It finds the young swimmers were no more likely to have breathing problems.