Effect of an exercise programme on stroke volume in patients with cystic fibrosis

Stroke volume can be reduced in cystic fibrosis (CF) patients with moderate lung disease. As no reports have specifically examined stroke volume after an aerobic conditioning programme, this question was studied in order to elucidate the role of low stroke volume in limiting exercise in patients with CF.Ten patients enrolled in a 12-week home exercise programme designed to raise heart rate to 75−80% of maximum for 15−30 min for ≥ 4 days per week. The primary outcome variable was change in stroke volume (indirect Fick [CO2] method) during constant sub-maximal exercise, with change in peak VO2 as secondary outcome.Training resulted in improvements in peak VO2(35.2 to 39.4 ml/kg/min) and stroke volume (51 ± 18 to 60 ± 18 ml), i.e. from 82 ± 25 to 94 ±22% of predicted. The improvement in peak VO2was highly correlated with the rise in exercise stroke volume. Stroke volume remained low despite completion of the training in patients with the lowest FEV1.The low stroke volume during exercise found in CF patients with mild to moderate airway obstruction is due mainly to deconditioning. Aerobic training improves stroke volume, which translates into improved peak VO2. Patients with greater obstruction may not experience this recognized benefit of regular exercise.