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NCT Number: NCT07258615

Longitudinal Ultrasound Assessment of Diaphragmatic and Respiratory Muscle Function Following Respiratory Muscle Training in Frail Older Adults

This study aims to evaluate the effects of an 8-week inspiratory muscle training program on diaphragmatic and respiratory muscle function in frail older adults aged 80 years and above. Frailty is associated with reduced physical capacity, impaired respiratory performance, and a higher risk of disability. Inspiratory muscle training is a simple, low-cost intervention that may improve breathing function, strength, and overall health in very old adults, but evidence in this age group remains limited.

Participants will be randomly assigned to one of two groups: a high-load inspiratory muscle training group or a low-load sham training group. Both groups will use a threshold device and perform 30 breaths once per day, five days per week, for eight weeks. The experimental group will train with progressively increasing resistance (50% to 80% of maximal inspiratory pressure), while the sham group will use a minimal and non-progressive load (15% of maximal inspiratory pressure). All sessions will be supervised and monitored for safety.

The main goal of the study is to determine whether inspiratory muscle training improves maximal inspiratory pressure (MIP), an established measure of global inspiratory muscle strength. Secondary outcomes include ultrasound-based assessments of diaphragmatic structure and function, such as diaphragm thickness, contractile fraction, diaphragmatic excursion, inspiratory time, and inspiratory velocity during deep breathing and sniff maneuvers. These measurements will help clarify the physiological adaptations produced by inspiratory muscle training in this population.

Assessments will be performed before the intervention, immediately after the 8-week program, and again at one and three months after the end of the intervention to examine both immediate and short-term effects. This study may contribute valuable evidence regarding the safety, feasibility, and clinical benefits of inspiratory muscle training in frail very old adults, supporting its potential implementation in rehabilitation and geriatric care.

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Key information

Conditions

Frailty Syndrome Age-Related Frailty Frailty Geriatric Health Pathologic Processes Pathological Conditions, Signs and Symptoms Respiratory Muscle Weakness

Age range

80 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Universidad Francisco de Vitoria

Pozuelo de Alarcón, Madrid, 28223, Spain

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults aged 80 years or older.
  • Clinical diagnosis of frailty, defined by a Short Physical Performance Battery (SPPB) score < 9.
  • Ability to stand and walk with or without assistive devices.
  • Ability to understand and follow instructions for inspiratory muscle training.
  • Stable medical condition for at least 3 months prior to enrollment.
  • Capacity to provide informed consent or availability of a legal representative.

Exclusion criteria

  • Acute or unstable cardiovascular, respiratory, or metabolic conditions.
  • Severe cognitive impairment that prevents understanding the procedures.
  • Diagnosis of neuromuscular diseases affecting respiratory muscles (e.g., ALS, myopathies).
  • Severe or uncontrolled hypertension (≥180/110 mmHg).
  • Recent thoracic or abdominal surgery (<3 months).
  • Severe musculoskeletal disorders limiting participation in training.
  • History of recurrent syncope, severe dizziness, or intolerance to respiratory maneuvers.
  • Any condition judged by the research team to compromise safety or participation.

Treatment and study plan

Inspiratory muscle training

Device

Participants perform 30 breaths once daily, 5 days per week for 8 weeks using a threshold inspiratory muscle training device. The load begins at 50% of maximal inspiratory pressure (MIP) and increases by 5 cmH₂O weekly up to 80% of MIP. Sessions are supervised and oxygen saturation and heart rate are monitored.

Sham Inspiratory Muscle Training

Device

Participants use the same device and schedule as the experimental group (30 breaths once daily, 5 days per week for 8 weeks) but with a constant load of 15% of maximal inspiratory pressure (MIP), with no weekly progression. This mimics the procedure while providing minimal physiological stimulus. Supervision and monitoring are identical to the experimental arm.

Primary outcomes

  1. Maximal Inspiratory Pressure (MIP)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Maximal Inspiratory Pressure (MIP) will be measured using a calibrated handheld manometer following standardized respiratory assessment guidelines. Participants will be instructed to perform a maximal inspiratory effort from residual volume through the mouthpiece with their nose occluded. At least three maneuvers will be recorded, ensuring less than 10% variability between attempts. The highest reproducible value (cmH₂O) will be used for analysis. This measure reflects global inspiratory muscle strength and is widely validated in older and frail populations.

Secondary outcomes

  1. Diaphragm Thickness at End-Expiration (DTE)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Diaphragm thickness at end-expiration will be measured using 2D ultrasound at the zone of apposition. Three measurements will be obtained and averaged. This variable reflects diaphragm muscle thickness at rest.

  2. Diaphragm Thickness at End-Inspiration (DTi)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Diaphragm thickness at end-inspiration will be measured using 2D ultrasound during a maximal inspiratory effort. Three measurements will be averaged. This variable reflects diaphragm contraction thickness.

  3. Diaphragm Thickening Fraction (DTF)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    The diaphragm thickening fraction will be calculated as:

    Diaphragm Thickening Fraction (DTF) = [(Diaphragm Thickness at End-Inspiration (DTi) - Diaphragm Thickness at End-Expiration (DTE)) / DTE] × 100.

    This percentage reflects diaphragm contractile capacity.

  4. Diaphragmatic Excursion During Deep Breathing (DMDB)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Diaphragmatic excursion during deep breathing will be assessed with M-mode ultrasound during a maximal inspiratory maneuver. The average of three reproducible measurements will be used to quantify the cranio-caudal diaphragm displacement.

  5. Inspiratory Time During Deep Breathing (DTDB)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Inspiratory time during deep breathing will be measured from the M-mode tracing as the time from the onset of diaphragm movement to its maximal excursion. This reflects the temporal characteristics of deep inspiration.

  6. Inspiratory Velocity During Deep Breathing (DVDB)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Inspiratory velocity will be calculated by dividing diaphragmatic excursion (DMDB) by inspiratory time (DTDB), providing an estimate of average inspiratory velocity.

  7. Diaphragmatic Excursion During Sniff Maneuver (DMVS)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Diaphragmatic excursion during a voluntary sniff will be measured with M-mode ultrasound during a rapid, forced nasal inspiration. The average of three reproducible efforts will be used to quantify rapid diaphragm displacement.

  8. Inspiratory Time During Sniff Maneuver (DTVS)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Inspiratory time during the sniff maneuver will be measured from the start of diaphragm movement to its peak excursion on the M-mode tracing.

  9. Inspiratory Velocity During Sniff Maneuver (DVVS)

    Time frame: Before-intervention; Immediately after intervention; 1-month after intervention; 3 months after intervention

    Inspiratory velocity during sniff will be calculated by dividing sniff excursion by the corresponding inspiratory time, reflecting rapid contractile performance.

Sponsors and collaborators

Lead sponsor

Universidad Francisco de Vitoria

Other

Registry information

Official study title

Longitudinal Ultrasound Assessment of Diaphragmatic and Respiratory Muscle Function Following Respiratory Muscle Training in Frail Older Adults: A Randomized, Double-Blind, Sham-Controlled Trial

Acronym: IMT-1

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Dec 2, 2025
Registry last updated
Feb 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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