Comparative Effects of Different Inspiratory Muscle Training Modalities in Patients With Heart Failure.
Enrolling by invitation · Not applicable · Has a placebo group
Conditions studied: Heart Failure, Heart Failure and Reduced Ejection Fraction, Heart Failure and Mildly Reduced Ejection Fraction, Muscle Weakness, Inspiratory Muscle Weakness
In brief
The purpose of this study is to compare the effects of three different modalities of inspiratory muscle training (IMT) in patients diagnosed with chronic heart failure who exhibit reduced or mid-range left ventricular ejection fraction (LVEF \< 50%). Patients will be recruited from cardiac rehabilitation programs and must be clinically stable before entering the protocol. The study has a total duration of 8 weeks and is divided into two distinct phases. During the first 2 weeks, participants will undergo a familiarization phase to learn the proper breathing techniques with the devices and to complete baseline resting and functional clinical evaluations. The following 6 weeks will comprise the effective training phase, consisting of 3 weekly sessions of high-intensity inspiratory training. Participants will be randomly assigned to one of three parallel groups: * Group 1 (Pressure-Threshold IMT): Participants will train using a mechanical pressure-threshold device at an initial high-intensity load of 60% of their baseline maximal inspiratory pressure (MIP). * Group 2 (Electronic Flow-Resistive IMT): Participants will train at a high-intensity load of 60% of their baseline MIP utilizing the PowerBreathe KH2 electronic device, which provides a dynamic, flow-dependent automated resistance. * Group 3 (Control / Sham IMT): Participants will perform the same breathing protocol but using a mechanical device set at a low, non-training intensity of 15% of their baseline MIP. For all three groups, training volume is standardized to 5 sets of 8 repetitions (40 inspiratory efforts per session). To ensure progressive overload, training intensity will be increased by 10% of the initial baseline MIP value every 2 weeks. The main outcomes to be evaluated before and immediately after the 8-week period include maximal inspiratory muscle strength, structural changes in respiratory muscles (diaphragmatic and parasternal intercostal thickening fraction measured via ultrasound), cardiac autonomic balance (heart rate variability), and health-related quality of life. Additionally, dynamic responses such as respiratory and locomotor muscle oxygenation (measured continuously via Near-Infrared Spectroscopy \[NIRS\] during a respiratory metabolic reflex provocation test) and overall cardiopulmonary exercise capacity (measured via an incremental cycle ergometer test) will be analyzed. This study aims to determine which training modality provides the most effective physiological adaptations to optimize rehabilitation in this population.
Key facts
- Study ID
- NCT07688863
- Run by
- Universidad Nacional Andres Bello
- People needed
- 60
- Starts
- 2026-06-17
- Expected to finish
- 2027-12-01
- Last updated by the study team
- 2026-07-07
Who can join
Age: 18 and older. Sex: any. Healthy volunteers: not accepted.
You may qualify if…
- Documented clinical diagnosis of chronic Heart Failure with Reduced Ejection Fraction (HFrEF) according to the European Society of Cardiology (ESC) guidelines.
- Left Ventricular Ejection Fraction (LVEF) less than or equal to 40% documented by echocardiography within the last 12 months.
- Clinically stable condition for at least 3 months prior to enrollment, with no hospitalizations or major changes in optimized medical therapy.
- New York Heart Association (NYHA) functional class I to IV.
- Evidence of inspiratory muscle weakness, defined as a baseline Maximal Inspiratory Pressure (MIP) < 70% of the predicted value for age and sex.
- Age greater than or equal to 18 years.
- Patient must be capable of understanding the protocol instructions and must provide signed written informed consent.
You may not qualify if…
- Presence of primary severe pulmonary or respiratory diseases (e.g., Chronic Obstructive Pulmonary Disease [COPD] GOLD stage III or IV, active asthma, severe pulmonary hypertension, or restrictive lung disease).
- Recent myocardial infarction, unstable angina, or coronary artery bypass graft (CABG) surgery within the last 6 months.
- Severe uncorrected valvular heart disease or complex, uncontrolled ventricular arrhythmias.
- Orthopedic, neurological, or musculoskeletal limitations that prevent the safe execution of an incremental cardiopulmonary exercise test on a cycle ergometer or the performance of the isometric handgrip protocol.
- Cognitive impairment or psychological conditions that limit the ability to follow instructions, maintain correct diaphragmatic breathing technique, or properly seal the training device mouthpiece.
- Current participation in another structured physical rehabilitation or formal sports training program that could confound the systemic results of the intervention.
- Any acute infectious, inflammatory, or medical condition that, in the investigator's opinion, poses a safety risk during high-intensity training.
Where it is running
- Universidad Andrés Bello, Campus Viña del Mar — Viña del Mar, Valparaiso, Chile
Full record on ClinicalTrials.gov
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