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.
Who can participate
Age range
18 Years
Sex
MALE
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* 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
Exclusion Criteria:
* 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
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Dynamic Inspiratory Muscle Strength Assessed by S-Index
Timeframe: Day 1, during the single assessment visit