Respiratory muscle (RM) strength and endurance is decreased in chronic obstructive pulmonary disease (COPD). Standard exercise rehabilitation programs do not improve RM function. Specific RM training can increase RM function, but the magnitude of improvement appears to be dependent on the magnitude of the training load. We hypothesise that (a) a RM training program based on principles of interval training established for whole-body exercise training will permit higher loads to be tolerated by patients with COPD and (b) permit greater increases in RM strength and endurance. Five subjects with COPD (FEV, 40±11(SD) % predicted) completed 8 weeks of RM training (3 sessions/week, each session required 7 x 2min loaded breathing + Imin rest). Inspiratory load was incremented each session. RM strength (PImax; maximum inspiratory pressure generated against an occluded airway) and endurance (Pthmax; maximum pressure generated against a progressively increasing inspiratory threshold load) were measured before and after the 8-week training period. In 4 subjects arterial blood lactate (La+) was measured during the endurance tests. RM training load commenced at 67±5% PImax and by week 8 subjects were training at 73±3% PImax. Following the training program increases were observed in PImax (78±22 to 92±19 cmH20, p<0.05), Pthmax (53±18 to 78±22 cmH20, pO.OI) and Pthmax/PImax (70±10 to 85±12%, p<0.01). During loaded breathing La+ production increased in 3 subjects (0.7±0.5 mmol/L), consistent with increased work performed by the RM. These findings show that consistent improvements in RM strength and endurance are observed in COPD patients where the RM are subject to interval training which permits workloads sufficiently high to exceed their training threshold.
|Issue number||SUPPL. 1|
|Publication status||Published - 2001|
- Respiratory muscle training