The additional effect of inspiratory muscle training as an adjunct to a general exercise training program in patients with COPD with inspiratory muscle weakness will be studied. The main hypothesis is that inspiratory muscle training combined with an exercise training program improves functional exercise capacity more than an exercise training program without the addition of an inspiratory muscle training program.

Inclusion Criteria:

• Patients with COPD
• Eligible to participate in an inpatient pulmonary rehabilitation program of 3 weeks
• Pi,max <60 centimeters of water or <50% of the predicted normal value

Exclusion Criteria:

• Major comorbidities preventing successful participation in an 8 week exercise training intervention
• use of non-invasive ventilation