Relationship between breath-hold time and physical performance in patients with cystic fibrosis

Rehabilitation including physiotherapy is an important part of the treatment used to help improve the quality of life of patients with cystic fibrosis (CF). The aim of this study was to determine the value of the breath-hold time as an index of exercise tolerance in patients with CF. Eighteen patients in different states of CF were included. The breath-hold time was measured in all patients. The fitness level was assessed by means of a progressive exercise test on a cycle-ergometer. During the test, oxygen uptake (VO2) and carbon dioxide elimination (VCO2) were measured breath by breath. The VO2 and working capacity (WC) were computed at the anaerobic threshold (AT) and at peak. Duration of breath-hold was 24.7 +/- 2.87 (mean +/- SEM) seconds, varying between 10 and 58. The breath-hold time (BHT) displayed a significant correlation with VO2 (r = 0.898), WC (r = 0.899) at the AT, and the peak VO2 (r = 0.895). Regression equations were: VO2 at the AT (ml/kg) = 5.53 + 0.42xBHT and WC at the AT (watt/kg)=0.56+0.38xBHT Our results suggest that the voluntary breath-hold time might be a useful index for prediction of the exercise tolerance of CF patients.