Aim: To examine the effects of a well-controlled, high-intensity inspiratory muscle training (IMT) program in combination with a 3-month pulmonary rehabilitation (PR) on functional exercise capacity in COPD patients with inspiratory muscle weakness in a large, multi-centre, randomised controlled trial. Methods: 169 patients (FEV 1 41±16%pred.) with low maximal inspiratory pressure (PImax 52±13 cmH 2 O) were recruited and randomized into an intervention group (IMT ≥50%PImax) or a control group (IMT ≤10%PImax). IMT was performed daily using a tapered flow resistive loading IMT device during PR. Results: Patients in the intervention group achieved larger gains in inspiratory muscle function (both strength and endurance; p<0.001). Clinically relevant and statistically significant improvements in 6MWD were observed in both groups, however, there was no statistically significant difference between groups (p=0.926). Endurance cycling exercise capacity increased significantly more in the intervention group (p=0.048) (Table 1).
Conclusion: Superior improvement in inspiratory muscle function after the addition of IMT to PR program did not translate into additional improvements in 6MWD. However, a larger improvement was observed in endurance cycling time which may be sensitive than the 6MWD for detecting improvements in exercise capacity when studying effects of adjuncts to PR.