High-intensity Inspiratory Muscle Training in Patients With Asthma

Overview

The aim of this study is to examine the effects of high-intensity and low-intensity inspiratory muscle training added to the standard pulmonary rehabilitation exercise program including aerobic and peripheral muscle strengthening training on respiratory muscle function, exercise capacity, dyspnea and health-related quality of life in asthmatic patients. The aim of the study was to examine whether there are intra-group changes and inter-group differences in the groups where low and high intensity inspiratory muscle training was applied. The cases meeting the inclusion criteria will be randomized and divided into two groups, the groups will be named as High Intensity Inspiratory Muscle Training Group (H-IMT) and Low Intensity Inspiratory Muscle Training Group (L-IMT).

Detailed description

Patients diagnosed with asthma by a chest diseases specialist and referred to pulmonary rehabilitation will be included in the study. The cases meeting the inclusion criteria will be randomized and divided into two groups, the groups will be named as High Intensity Inspiratory Muscle Training Group (H-IMT) and Low Intensity Inspiratory Muscle Training Group (L-IMT). Inspiratory muscle training will be carried out in the form of 2 minutes of work and 1 minute break for a total of 21 minutes, starting from 80% of the maximum inspiratory pressure determined by mouth pressure measurement for the H-IMT Group and 30% for the L-IMT Group. An 8-week training will be carried out by increasing the planned load by 5% every two weeks. In addition, breathing exercises, strengthening exercises and walking training on flat ground will be given to both groups in the form of a home program. The training program will be 8 weeks in total, 3 days a week. will be given online exercises, synchronized 2 days a week, and a home program for 1 day, accompanied by a physiotherapist, via videoconference on the smartphone. A total of 24 sessions will be held.

Interventions

• Other High Intensity Inspiratory Muscle Training Group (H-IMT)
  Respiratory muscle strengthening training will be given with a resistive threshold inspiratory muscle strengthening device. Initially, it will be worked out vigorously at 80% of the maximum inspiratory pressure determined by mouth pressure measurement. The load will be increased weekly.
• Other Low Intensity Inspiratory Muscle Training Group (L-IMT)
  Respiratory muscle strengthening training will be given with a resistive threshold inspiratory muscle strengthening device. Initially, it will be worked out vigorously at 30% of the maximum inspiratory pressure determined by mouth pressure measurement. The load will be increased weekly.

Primary outcome measures

• Maximal inspiratory pressure (MIP) measurement [Time frame: Change from baseline respiratory muscle strength at 8 weeks]
• Six minute walking test [Time frame: Change from baseline 6 minute walking distance at 8 weeks]
• Modified Medical Research Council (mMRC) Dyspnea Scale [Time frame: Change from baseline dyspnea perception at 8 weeks]

Secondary outcome measures (9)

• Forced Vital Capacity (FVC) [Time frame: Change from baseline FVC at 8 weeks]
• Forced Expiratory Volume (FEV1) [Time frame: Change from baseline FEV1 at 8 weeks]
• Peak Expiratory Flow (PEF) [Time frame: Change from baseline PEF at 8 weeks]]
• FEV1/FVC [Time frame: Change from baseline FEV1/FVC at 8 weeks]]
• Asthma Control Test (ACQ) [Time frame: Change from baseline ACQ score at 8 weeks]
• Peripheral muscle strength [Time frame: Change from baseline peripheral muscle strength at 8 weeks]
• Asthma Quality of Life Scale (AQLQ) [Time frame: Change from baseline AQLQ score at 8 weeks]]
• St. George Respiratory Questionnaire (SGRQ) [Time frame: Change from baseline SGRQ score at 8 weeks]
• International Physical Activity Questionnaire- short form [Time frame: Change from baseline physical activity level at 8 weeks]

Eligibility criteria

Inclusion criteria

• Being between the ages of 18-65 years
• Having been diagnosed with severe persistent, non-allergic asthma by a pulmonologist in accordance with the Global Initiative for Asthma (GINA) guideline criteria,
• Patients with type 2 inflammation markers. According to accepted standards; peripheral eosinophils <150/µL and/or negative skin prick test and/or total IgE <30 kU/L
• Bronchodilator response (>12% or 200 mL improvement in FEV1% predicted following inhalation of 400 mg salbutamol)
• Those who were diagnosed at least 6 months ago and are under follow-up and treatment, and/or patients whose asthma is under control

Exclusion criteria

• Having recently had a respiratory tract infection recently (within the last month),
• Having a smoking history of more than 10 pack-years or having a history of smoking within 6 months after quitting smoking
• Having received oral corticosteroid treatment in the last 4 weeks,
• Having a Body Mass Index >35,
• Eosinophilic Granulomatosis Polyangiitis (EGPA) and Allergic Bronchopulmonary Aspergillosis (ABPA),
• Vasculitis,
• History of malignancy,
• Pregnancy,
• Previous lung surgery, use of long-term oxygen therapy
• Having accompanying restrictive lung diseases (advanced kyphoscoliosis, ankylosing spondylitis) and neuromuscular diseases (myasthenia gravis, muscular dystrophies, myopathies) that will prevent healthy respiratory function testing and rehabilitation.
• Having conditions such as cognitive dysfunction, mental retardation, dementia that make it difficult to implement the protocol or interpret the study results

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Double blind

Primary purpose

Treatment

Study locations

Turkey (Türkiye) · 1 center

• Esra Pehli̇van — Istanbul

Publications

• Kocak C, Pehlivan E, Baslilar S. High- vs. low-intensity inspiratory muscle training in asthma: effects on respiratory muscles, exercise performance, dyspnea, and health-related quality of life. J Asthma. 2025 Oct;62(10):1776-1788. doi: 10.1080/02770903.2025.2519103. Epub 2025 Jun 20. PMID 40524414

Identifiers

NCT: NCT06516848 · Asthma_IMT

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗