The purpose of this study is to determine whether a high intensity short duration inspiratory muscle training is feasible, secure and effective to improve respiratory muscle function (strength and resistance), health-related quality of life, and to assess potential correlations with health resources utilization.

Patients with chronic heart failure (CHF) often refer exercise intolerance, marked fatigue and dyspnea at low exercise intensities. This characteristic feature might be generated by respiratory and skeletal muscle dysfunction, and it´s has been described as a comorbid status, reflecting the systemic impact of heart failure. Despite the availability of effective pharmacologic treatments, patients with CHF continue to experience progressively worsening symptoms, frequent hospital admission and premature death. Reduced physical functioning, role limitation, and lack of energy may interfere with daily activities as the condition worsens and thereby severely reduce the quality of life in CHF patients. The ACCF/AHA Guidelines for the diagnosis and management of heart failure recommend exercise training as an adjunctive approach to improve clinical status in stable adult patients with current or prior symptoms of heart failure and reduced left ventricular ejection fraction. A wide variety of studies have focussed on respiratory muscles abnormalities in CHF patients. Reduced strength and endurance of respiratory muscles are currently recognized as additional factors implicated in the limited exercise response and quality of life, as well as in a poor prognosis. Additionally, inspiratory muscle training (IMT) has shown to result in improvements on inspiratory strength, functional capacity, ventilatory response to exercise, recovery oxygen uptake kinetics, and quality of life of CHF patients with respiratory muscle weakness. The optimal training scheme remains still to be defined. Most of clinical trials have demonstrated the effectiveness of a low-intensity IMT (maximum 38 cmH2O), but there is little information of the training effects when using higher training loads. Our research group has demonstrated that a short-time high-intensity respiratory training in patients with chronic obstructive pulmonary disease afford to reach good functional results in a shorter time, which affords to make more efficient in terms of time the rehabilitation program and to reach to more patients.

Inclusion Criteria:

1. age over 18 years;
2. chronic heart failure (CHF) of any etiology;
3. clinically stable condition, with no worsening of heart failure or change in cardiac medication in the previous 3 months and during the study; and
4. ability to understand and accept the trial procedures and to sign an informed consent form in accordance with national legislation.

Exclusion Criteria:

1. previous history of any chronic respiratory disease;

2. not to have performed any kind of general or respiratory training in the previous 3 months.

   • Prior to randomization, all patients' clinical assessment and echocardiographic measurements were done by a cardiologist and all patients underwent pulmonary function tests.