Blood flow regulation and oxidative stress during submaximal cycling exercise in patients with cystic fibrosis

Background: The impact of blood flow regulation and oxidative stress during exercise in cystic fibrosis (CF) has yet to be investigated. Methods: A maximal graded exercise test was conducted to determine exercise capacity (VO ₂ peak) and peak workload in 14 pediatric patients with mild CF (age 14 ± 3 y, FEV ₁ 93 ± 16 % predicted) and 14 demographically-matched controls. On a separate visit, participants performed submaximal cycling up to 60% of peak workload where brachial artery blood velocity was determined using Doppler ultrasound. Retrograde and antegrade components were further analyzed as indices of blood flow regulation. Results: The cumulative AUC for retrograde velocity was lower in patients versus controls (1770 ± 554 vs. 3440 ± 522 cm, P = 0.038). In addition, an exaggerated oxidative stress response during exercise occurred in patients only (P = 0.004). Conclusion: These data suggest that patients with mild CF exhibit impaired blood flow regulation and an exaggerated oxidative stress response to submaximal exercise.