Predicting Dynamic Inspiratory Muscle Strength in COPD and Asthma Patients

NCT07598292 | Completed

• 1 other identifier: 2026-01
• Study Type: observational
• Target: 123
• Locations: 1 country
• Sites: 1

Brief Summary

This observational study evaluates whether dynamic inspiratory muscle strength can be estimated in patients with chronic obstructive pulmonary disease (COPD) and asthma using simple clinical and performance-based measurements. Dynamic inspiratory muscle strength was assessed using the S-Index, which reflects the pressure generated during a fast and forceful inspiration while airflow is maintained. The study included adult male patients diagnosed with COPD or asthma. Participants completed respiratory muscle strength assessment, pulmonary function testing, body composition assessment, and a fixed-pressure inspiratory muscle performance test using a threshold loading device set at 30 cmH₂O. The number of inspiratory repetitions performed until task failure and related respiratory variables were recorded. The main aim of the study was to develop prediction models for estimating S-Index values from accessible measures such as peak inspiratory flow, inspiratory repetition performance, spirometry parameters, and body composition variables. The study may help determine whether dynamic inspiratory muscle strength can be estimated in clinical settings where direct S-Index measurement devices are not available.

Conditions

Chronic Obstructive Pulmonary Disease (COPD); Asthma

Keywords

Dynamic inspiratory muscle strength; S-Index; Inspiratory muscle performance; Respiratory muscle strength; Spirometry

Outcome Measures

Primary Outcomes (1)

• Dynamic Inspiratory Muscle Strength Assessed by S-Index

  Dynamic inspiratory muscle strength was assessed using the S-Index measured with the POWERbreathe K5 device in single-breath test mode. Participants performed maximal and rapid inspiratory efforts after full expiration to residual volume. The highest S-Index value obtained from repeated maximal inspiratory efforts was recorded in cmH₂O.

  Day 1, during the single assessment visit

Secondary Outcomes (8)

• Number of Inspiratory Repetitions to Task Failure

  Day 1, during the single assessment visit

• Time to Task Failure During Fixed-Pressure Inspiratory Loading

  Day 1, during the single assessment visit

• Forced Vital Capacity

  Day 1, during the single assessment visit

• Forced Expiratory Volume in One Second

  Day 1, during the single assessment visit

• FEV1/FVC Ratio

  Day 1, during the single assessment visit.

Study Arms (2)

COPD Patients

Adult male patients with a clinical diagnosis of chronic obstructive pulmonary disease who underwent dynamic inspiratory muscle strength assessment, spirometry, body composition assessment, and fixed-pressure inspiratory muscle performance testing.

Asthma Patients

Adult male patients with a clinical diagnosis of asthma who underwent dynamic inspiratory muscle strength assessment, spirometry, body composition assessment, and fixed-pressure inspiratory muscle performance testing.

Eligibility Criteria

• Age: 18 Years+
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

The study population consisted of adult male patients with a clinical diagnosis of chronic obstructive pulmonary disease or asthma who were recruited from clinical units of Çorum Erol Olçok Training and Research Hospital, Hitit University, Türkiye. Eligible patients were enrolled during the study period if they were able to perform the respiratory muscle and pulmonary function measurements with correct technique and provided written informed consent.

You may qualify if:

• Being 18 years of age or older
• Having a clinical diagnosis of chronic obstructive pulmonary disease or asthma
• Being able to perform fixed-pressure inspiratory muscle loading and S-Index measurements in accordance with the instructions and with correct technique
• Having experienced no additional clinical condition within the previous 12 weeks, apart from the existing chronic respiratory disease, that could acutely affect respiratory function
• Having signed the informed consent form approved by the ethics committee

You may not qualify if:

• Smoking
• Inability to perform fixed-pressure inspiratory muscle loading or dynamic respiratory muscle strength assessment according to the technical requirements of the measurement protocols
• Inability to obtain reliable data due to insufficient coordination, motivation, or volitional effort
• Presence of a musculoskeletal injury or surgical history affecting the diaphragm, thorax, spine, or abdominal region that could significantly impair respiratory mechanics
• Presence of neurological conditions that may affect respiratory muscle function, such as neuromuscular diseases, peripheral nerve damage, or central nervous system disorders

Sponsors & Collaborators

• Hitit University: lead

Study Sites (1)

Hitit University Çorum Erol Olçok Training and Research Hospital

Çorum, Turkey (Türkiye)

Location

Related Publications (3)

• Areias GS, Santiago LR, Teixeira DS, Reis MS. Concurrent Validity of the Static and Dynamic Measures of Inspiratory Muscle Strength: Comparison between Maximal Inspiratory Pressure and S-Index. Braz J Cardiovasc Surg. 2020 Aug 1;35(4):459-464. doi: 10.21470/1678-9741-2019-0269.

  PMID: 32864924 BACKGROUND

• Caruso P, Albuquerque AL, Santana PV, Cardenas LZ, Ferreira JG, Prina E, Trevizan PF, Pereira MC, Iamonti V, Pletsch R, Macchione MC, Carvalho CR. Diagnostic methods to assess inspiratory and expiratory muscle strength. J Bras Pneumol. 2015 Mar-Apr;41(2):110-23. doi: 10.1590/S1806-37132015000004474.

  PMID: 25972965 BACKGROUND

• American Thoracic Society/European Respiratory Society. ATS/ERS Statement on respiratory muscle testing. Am J Respir Crit Care Med. 2002 Aug 15;166(4):518-624. doi: 10.1164/rccm.166.4.518. No abstract available.

  PMID: 12186831 BACKGROUND

MeSH Terms

Conditions

Pulmonary Disease, Chronic Obstructive; Asthma

Condition Hierarchy (Ancestors)

Lung Diseases, Obstructive; Lung Diseases; Respiratory Tract Diseases; Chronic Disease; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Bronchial Diseases; Respiratory Hypersensitivity; Hypersensitivity, Immediate; Hypersensitivity; Immune System Diseases

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: May 7, 2026
• First Posted: May 20, 2026
• Study Start: February 2, 2026
• Primary Completion: March 27, 2026
• Study Completion: March 27, 2026
• Last Updated: May 20, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)