Inspiratory Muscle Training for People With Heart Failure

Summary

Heart failure is frequently associated with inspiratory muscle weakness, which contributes to dyspnea, reduced exercise capacity, impaired quality of life, and adverse cardiovascular outcomes. Although inspiratory muscle training (IMT) is a recommended adjunct to cardiovascular rehabilitation, the optimal training modality remains uncertain, particularly among patients with reduced and preserved ejection fraction.

This randomized controlled trial will evaluate the efficacy of a novel inspiratory muscle training protocol using tapered flow resistive loading (TFRL) compared with conventional threshold loading (TL) and usual care. A total of 108 clinically stable patients with heart failure (NYHA class II-III) will be enrolled. Participants will be stratified according to heart failure phenotype (reduced or preserved ejection fraction) and allocated to one of three groups: TFRL, TL, or control. Both training interventions will be performed for 8 weeks in combination with supervised exercise-based cardiac rehabilitation.

Primary and secondary outcomes will include inspiratory muscle strength and endurance, exercise capacity, pulmonary function, dyspnea, skeletal muscle oxygenation, autonomic balance, arterial stiffness, and health-related quality of life. The study is powered to detect moderate between-group differences and interaction effects with 80% statistical power and a two-sided alpha level of 0.05. Changes over time and between groups will be analyzed using analysis of covariance (ANCOVA), adjusting for baseline inspiratory muscle strength.

The trial aims to determine whether TFRL provides superior clinical and physiological benefits compared with conventional inspiratory muscle training and whether treatment responses differ according to heart failure phenotype.

Conditions

• Heart Failure

Interventions

OTHER

Inspiratory muscle training with Tapered Resistive Load

The resistance pressure of the Tapered Resistive Load Device (POWER Breathe KH2) will be set at 60% of each participant's maximum inspiratory pressure measured at baseline. Re-evaluations of peak inspiratory pressure in both exercise groups will be carried out every 2 weeks to perform load progression. The training protocol has 6 levels depending on the rest period. The first level has 60 second rest periods and from the second level through the sixth level, the rest period will be reduced to 45, 30, 15, 10, and 5 seconds. All participants in all groups will perform 6 inspiratory efforts at each level. In total, each participant will perform 36 inspiratory efforts (6 levels x 6 efforts = 36 total efforts). Training sessions will be supervised and performed three times a week for 8 weeks.

OTHER

Inspiratory muscle training with threshold load

The resistance pressure of the threshold device (POWER Breathe Plus Medic) will be set at 60% of each participant's maximum inspiratory pressure measured at baseline. Re-evaluations of peak inspiratory pressure in both exercise groups will be carried out every 2 weeks to perform load progression. The training protocol has 6 levels depending on the rest period. The first level has 60 second rest periods and from the second level through the sixth level, the rest period will be reduced to 45, 30, 15, 10, and 5 seconds. All participants in all groups will perform 6 inspiratory efforts at each level. In total, each participant will perform 36 inspiratory efforts (6 levels x 6 efforts = 36 total efforts). Training sessions will be supervised and performed three times a week for 8 weeks.

OTHER

Concurrent Exercise Training

The concurrent training program will include aerobic and resistance exercise. Aerobic training will begin after a 5-minute warm-up at low to moderate intensity. This will be followed by 40 minutes of aerobic exercise at the anaerobic threshold (AT) power (PO) obtained from a cardiopulmonary exercise test. Each session will include 8 intervals of 3 minutes (110-120% of AT-PO) and 8 intervals of 2 minutes of active recovery (70-80% of AT-PO). Training intensity increased by 10% each week while maintaining a Borg scale rating of 13-14, provided that no abnormal cardiovascular or electrocardiographic signs or symptoms were observed. Resistance training will be conducted in 10-minute sessions with at least 6 different exercises using between 40% and 50% of one-repetition maximum (1RM). The 1RM will be calculated using Brzycki's submaximal repetition formula (Weight/(1.0278 - (0.0278\*Reps)). Subsequently, 5 minutes of stretching will be performed as a cool-down.

Sponsors & Collaborators

• Universidad Nacional Andres Bello

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-06-30

Primary Completion

2028-05-31

Completion

2028-07-31

Countries

• Chile

Study Locations