Inspiratory Muscle Training and Functional Electrical Stimulation for Treatment of HFpEF

Patients allocated to IMT arm will receive standard medical treatment and will be instructed to train at home twice daily, for 20 minutes each session, and during 12 weeks using a threshold inspiratory muscle trainer (Threshold IMT®, Respironics Inc.). All of them will be instructed by a respiratory therapist and educated to maintain a diaphragmatic breathing during the training period. The subjects start breathing at a resistance equal to 25-30% of their maximal inspiratory pressure (MIP) for 1 week. The respiratory therapist examines the patients at weekly intervals by checking the diary card and measuring their MIP each time. The resistance is modified each session according to their 25-30% of their MIP measured.

Patients allocated to FES arm will receive standard medical treatment and will be trained in a FES program of both legs by a physiotherapist for 45 minutes a day, 2 days per week for a total of 12 weeks. Eight adhesive electrodes are positioned on the skin over the quadriceps and gastrocnemius muscles of both legs. The stimulator is configured to deliver a direct electrical current at 25 Hz for 5 seconds followed by a 5-second rest. The intensity of the stimulation is adjusted to achieve a visible muscle contraction without discomfort.

Patients allocated to this arm will not receive any physical therapy, only standard medical treatment. They will be checked weekly by a physiotherapist who measures their maximal inspiratory mouth pressure each time.