In some centers, recommendations for physical activity are part of regular outpatient care offered to cystic fibrosis (CF) patients following the groundbreaking study of Nixon et al. published in the New England Journal of Medicine in 1992. Nixon et al. noted, "The results of this study indicate a notable association between aerobic fitness and survival at eight years among patients with cystic fibrosis… The results suggest that exercise testing may be a valuable tool for determining prognosis in patients with cystic fibrosis."
Since the 1992 NEJM paper, numerous publications have confirmed the clinical value of CPET in the evaluation and management of CF, but its utilization in CF centers in the US has remained sporadic. With the current introduction of disease modifying medications that can ameliorate or reverse the pathological cellular effects of abnormal cystic fibrosis transmembrane regulator (CFTR) receptors, improvement in lung function and general health of CF patients is among the most transformative in the history of medicine.
The novel CFTR modulators along with the steady improvement in the management of nutritional and infectious disease complications over the past several decades has led to marked increases in the health- and lifespan of people with CF. Even conditions like obesity and related cardiometabolic diseases, rarely found earlier in the CF symptomatology lexicon, are increasing as longevity and improved care accelerate. However peak Ṿ̇O₂ has long been known to be lower in CF than in healthy controls.
This reduction in skeletal muscle function in CF is not completely understood but likely results from a combination of mechanisms including impaired airway clearance, the effect of increased inflammatory mediators and nutrition on skeletal muscle development, possible genotype factors, and expression of CFTR in skeletal muscle. Understanding and utilizing therapeutic exercise in the age of disease modifying drugs is an exciting future avenue in CF care and research.