Inspiratory Muscle Training in Heart Failure

The aim of this study is to investigate the potential effects of inspiratory muscle training on cardiovascular, respiratory, physical, and psychosocial functions in patients with heart failure.

Heart failure is a syndrome that leads to decreased cardiac output, inflammation, increased catabolism, and prolonged immobilization, causing inspiratory muscle weakness. Cardiac rehabilitation is a well-known treatment approach in heart failure however, the participation rate in cardiac rehabilitation is low. Therefore, inspiratory muscle training may serve as an alternative approach in patients with heart failure. Patients will be randomly allocated into the inspiratory muscle training group and control group. The inspiratory muscle training (IMT) group will carry out IMT sessions three days per week for 8 weeks by using an inspiratory threshold loading device. Each session will consist of seven cycles including 2 min of breathing on an inspiratory loading device followed by 1 min of rest and will last 21 min. IMT will be performed at the tolerable maximum load for each 2-min work interval and will be progressively increased over the 8 weeks. The control group will perform unloaded IMT by using an inspiratory threshold loading device during all training sessions. Data will be collected before and after the treatment by a masked outcome assessor.

Inspiratory muscle training will be performed three sessions per week as one supervised and two unsupervised for 8 weeks using an inspiratory muscle training device (PowerBreath). The inspiratory muscle training session will consist of 7 cycles including a 2:1 ratio of work and rest interval. Resistance will be adjusted to the highest tolerable load and will be gradually increased.

Sham inspiratory muscle training will be performed three sessions per week as one supervised and two unsupervised for 8 weeks using an inspiratory muscle training device (PowerBreath). The inspiratory muscle training session will consist of 7 cycles including a 2:1 ratio of work and rest interval. Resistance will be adjusted to the unloaded.

Heart rate variability analysis, which gives information about the cardiac autonomic function, will be obtained from a short-term 5-min ECG recording using a SphygmoCor device.

Maximal inspiratory pressure (MIP) will be measured using an electronic mouth pressure device. A higher inspiratory pressure indicates better inspiratory muscle strength.

Maximal expiratory pressure (MEP) will be measured using an electronic mouth pressure device. A higher expiratory pressure indicates better expiratory muscle strength.

Respiratory muscle endurance will be measured using an inspiratory muscle training device (PowerBreath). Higher values indicate better respiratory muscle endurance.

Dyspnea will be assessed with the modified Medical Research Council (mMRC) scale. mMRC is a scale of 5 items (0-4). Higher scores indicate higher dyspnea perception.

Quadriceps muscle strength will be measured using a dynamometer. Higher values indicate better quadriceps muscle strength.

Physical activity will be assessed with an activity monitor (SenseWear Armband) for consecutive 7 days.

Physical frailty will be assessed with Field Frailty Phenotype. Field Frailty Phenotype consists of 5 criteria and scores 0 to 5. A score of 3-5 indicates frailty.

Fatigue will be assessed with Fatigue Impact Scale. Fatigue Impact Scale is a 40-item questionnaire. Each item is scored from 0-4 (a 4-point severity scale). The highest score is 160.

Disease-specific quality of life will be assessed with Minnesota Living with Heart Failure Questionnaire. It is a 21-item questionnaire. Each item is scored from 0-5 (a 5-point severity scale). The highest score is 105.

Health-related quality of life will be assessed with Short-Form 36 Health Survey Questionnaire (SF-36). SF-36 consists of 8 domains. Higher scores indicate a better health-related quality of life.

Inclusion Criteria: Diagnosis of heart failure with reduced ejection fraction Clinically stable Functional class II-III according to the New York Heart Association functional classification Having inspiratory muscle weakness (MIP<70%) Volunteer to participation Exclusion Criteria: Congenital heart disease Severe valvular heart disease Cardiac device such as implantable cardioverter defibrillator or cardiac resynchronization therapy Neurological disease Conditions that may limit the physical mobility