High-intensity inspiratory muscle training and diaphragm thickness in severe COPD: a prospective pilot study

High-intensity inspiratory muscle training (IMT) has been reported to increase diaphragm thickness in healthy adults, but evidence in severe chronic obstructive pulmonary disease (COPD) remains scarce. This prospective pilot study evaluated the effects of high-intensity IMT on diaphragm thickness and functional outcomes in nine patients with severe COPD who had completed standard respiratory rehabilitation. Participants performed 30 breaths per day at 60 % of maximum inspiratory pressure for 12 weeks. Diaphragm thickness at maximum inspiration increased from 4.7 to 5.6 mm, maximum inspiratory pressure from 57.1 to 68.1 cmH₂O, 6-min walk distance from 318 to 366 m, and COPD Assessment Test scores from 19 to 12, both exceeding the minimal clinically important difference thresholds (all p < 0.01). These findings suggest that high-intensity IMT may be a feasible and beneficial adjunct for improving inspiratory function and symptoms in patients with severe COPD.