Aim: To investigate any relationship between, i)quality of training sessions, ii)improvements in inspiratory muscle function, iii)changes in exercise capacity following well-controlled, high-intensity inspiratory muscle training (IMT), in combination with 3-months of pulmonary rehabilitation. Methods: 169 patients (FEV1 41±16%pred.) with low maximal inspiratory pressure (PImax 51±15%pred) were recruited and randomized into an intervention group (IMT ≥50%PImax) or a control group (IMT ≤10%PImax). Patients participated in daily IMT using a tapered flow resistive loading device. Subgroup analyses were performed by pooling the data of both groups and subsequently dividing it into tertiles based on improvements in PImax after the intervention. Results: Training characteristics (total inspiratory work performed/session, average peak power/session, and IMT intensity) were significantly related to improvements in PImax (Figure 1A-1C).
Average training compliance (84±19%) was not associated with change in PImax (p-for-trend=0.129). Larger improvements in PImax were related to larger increases in endurance cycling time (Figure 1D). Conclusion: The quality rather than the number of performed training sessions is strongly associated with improvement in inspiratory muscle strength which in turn relates to improvements in endurance cycling time.