Inspiratory muscle training in patients with cystic fibrosis

Little information is available about the effects of inspiratory muscle tra ining in patients with cystic fibrosis (CF). In this study the effects of i nspiratory-threshold loading in patients with CF on strength and endurance of the inspiratory muscles, pulmonary function, exercise capacity, dyspnoea and fatigue were evaluated. Sixteen patients were assigned to one of two groups using the minimization method: eight patients in the training group and eight patients in the cont rol group. The training was performed using an inspiratory-threshold loadin g device. Patients were instructed to use the threshold trainer 20 min a da y, 5 days a week for 6 weeks. Patients in the training group trained at ins piratory threshold loads up to 40% of maximal static inspiratory pressure ( Pimax) and patients in the control group got 'sham' training at a load of 1 0% of Pimax. No significant differences were found among the two groups in gender, age, weight, height, pulmonary function, exercise capacity, inspira tory-muscle strength and inspiratory-muscle endurance before starting the t raining programme. Mean (sD) age in the control group was 19 (5 5) years, m ean (sD) age in the training group was 17 (52) years. Mean FEV1 in both gro ups was 70% predicted, mean inspiratory-muscle strength in both groups was above 100% predicted. All patients except one, assigned to the training group, completed the prog ramme. After 6 weeks of training, mean inspiratory-muscle endurance (% Pima x) in the control group increased from 50% to 54% (P = 0.197); in the train ing group mean inspiratory muscle endurance (% Pimax) increased from 49% to 66% (P = 0.003). Statistical analysis showed that the change in inspirator y-muscle endurance (% Pimax) in the training group was significantly higher than in the control group (P = 0.012). After training, in the training gro up there was a tendency of improvement in Pimax with an increase from 105 t o 123% predicted, which just fell short of statistical significance (P = 0. 064). After training no significant differences were found in changes from baseline in pulmonary function, exercise capacity, dyspnoea and fatigue. It is concluded that low-intensity inspiratory-threshold loading at 40% of Pi max was sufficient to elicit an increased inspiratory-muscle endurance in p atients with CF.