Recruiting

Mechanical Unloading

Sponsor:

University of Texas Southwestern Medical Center

Code:

NCT05028309

Conditions

Obesity

Aging

Eligibility Criteria

Sex: All

Age: 65 - 70+

Healthy Volunteers: Accepted

Interventions

Mechanical unloading of the Thorax using an external cuirass

Study Details

Brief summary:

The overall objective of this application is to investigate the effects of obesity on lung function, exercise tolerance, and DOE in older obese adults as compared with older adults without obesity, using a novel probe for mechanically unloading the thorax at rest and during exercise. The investigators will use 1) continuous negative cuirass pressure, and 2) assisted biphasic cuirass ventilation to decrease obesity-related effects in older obese adults. Our approach will be to examine respiratory function, exercise tolerance, and DOE with and without mechanical unloading in older obese men and women (65-75 yr), including those with respiratory symptoms (defined by a score of 1 or 2 on the modified Medical Research Council Dyspnea Scale), as compared with older adults without obesity.

Specific Aims: The investigators will test the following hypotheses in older adults with and without obesity:

Aim 1) Obesity will decrease respiratory function but to a greater extent in older obese adults with respiratory symptoms, (as evidenced by altered pulmonary function and breathing mechanics at rest); Aim 2) Obesity will decrease exercise tolerance (as evidenced by peak V•O2 in ml/min/kg, i.e., physical fitness), but not cardiorespiratory fitness (as evidenced by peak V•O2 in % of predicted based on ideal body wt), except in older obese adults with respiratory symptoms where both may be reduced during graded cycle ergometry.

Aim 3) Obesity will increase DOE but to a greater extent in older obese adults with respiratory symptoms as evidenced by increased ratings of perceived breathlessness (sensory \& affective dimensions) during exercise.

Aim 4) Mechanical unloading of the thorax will improve respiratory function, submaximal exercise tolerance, and DOE in older obese adults, but to a greater extent in older obese adults with respiratory symptoms.

Conditions

Obesity

Aging

Study ID

NCT05028309

Start date

Dec 1, 2021

Status verified date

Aug, 2026

Completion date

Dec 31, 2026

Anticipated

Primary completion date

Dec 31, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 65 - 70+

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Otherwise healthy older adults 65-75 years of age with normal lung function; men 30< %body fat ≤50 and women 35< %body fat ≤55; and ability to perform pulmonary and exercise test. Other inclusion criteria include the following:
  • Nonsmokers who have no history of smoking
  • No personal history of significant mental illness
  • No weight loss dietary restrictions
  • No current or past history of significant substance or alcohol abuse
  • No history, evidence, or uncontrolled symptoms of heart disease
  • No history of uncontrolled hypertension
  • No current medications that may interfere with exercise capacity
  • No recent history or indication of asthma
  • No musculoskeletal abnormality that would preclude exercise
  • No serious health conditions that would preclude study goals or participation in exercise (per PI \& medical staff \& preliminary or follow up testing; including significant other diseases, occult asthma, prior surgeries-especial lung or abdominal, or history of chemotherapy that could affect lung or heart function)
  • Only postmenopausal women will be included.
  • Women on hormone replacement therapy will be allowed to participate if the dosage remains similar during the entire protocol.

Exclusion Criteria:

  • Volunteers with a mMRC score of 3 or 4 will be excluded due to likeliness of underlying disease.
  • Individuals participating in regular vigorous conditioning exercise such as running, jogging, aerobics, cycling, or swimming more than three times per week will be excluded. However, if subjects have an exceedingly high exercise capacity (greater than 2 SD of predicted), they will be excluded.
  • Maximal cycle ergometry test will be used to determine if further participation in testing is appropriate for the participant (e.g., normal exercise test, exclude presence of provokable ECG changes suggestive of heart disease, or dangerous arrhythmias or exercise induced hypertension or bronchoconstriction. If the participant develops an abnormal ECG or shows other signs of exercise intolerance or if signs of cardiovascular disease are noted during the exercise test, it will be terminated and the participant will be referred to their personal physician for further evaluation (see DMSP).
  • Premenopausal women will be excluded.

Study Design

Enrollment

72 participants

Anticipated

Allocation

Non randomized

Intervention Model

Single group

Primary purpose

Other

Interventions and Outcome Measures

Arms

experimental: Interventional Arm

Older group of adults (65-75 yrs). Everyone enrolled uses the 'intervention'/ external cuirass - mechanical unloading of thorax

Interventions

Mechanical unloading of the Thorax using an external cuirass

External cuirass (i.e., a plastic shell over the thorax) will be used to mechanically unload the chest wall. The cuirass has different operating modes. It can generate a constant negative pressure over the chest wall (e.g., -20cmH2O) or it can be triggered off mouth flow so it can generate a negative pressure on the chest wall during inspiration (e.g., -21cmH2O) and a positive pressure during expiration (e.g., +7cmH2O).

Primary outcome measure

  • Change in Pulmonary Function: Lung Volumes [ Time Frame: Outcome measures will be assessed within 24-48hrs after completion of each study condition (baseline, control, continuous, and dynamic) ]
  • Change in Exercise Tolerance - Peak VO2 [ Time Frame: Outcome measures will be assessed within 24-48hrs after completion of each study condition (baseline, control, continuous, and dynamic). ]
  • Change in Dyspnea on Exertion [ Time Frame: Outcome measures will be assessed within 24-48hrs after completion of each study condition (baseline, control, continuous, and dynamic). ]
  • Changes in PANAS Questionnaire [ Time Frame: Outcome measures will be assessed within 24-48hrs after completion of each study condition (baseline, control, continuous, and dynamic). ]
  • Modified Medical Research Council Dyspnea Scale (mMRC Dyspnea Scale) [ Time Frame: Outcome measures will be assessed immediately after completion of mMRC questionnaire (during study visit 2) ]
  • Dyspnoea-12 [ Time Frame: Outcome measures will be assessed immediately after completion of Dyspnoea-12 questionnaire (during study visit 2) ]
  • ASI [ Time Frame: Outcome measures will be assessed immediately after completion of ASI questionnaire (during study visit 2) ]
  • HADS [ Time Frame: Outcome measures will be assessed immediately after completion of HADS questionnaire (during study visit 2) ]
  • SDS-MC [ Time Frame: Outcome measures will be assessed immediately after completion of MC-SDS questionnaire (during study visit 2) ]
  • IPAQ [ Time Frame: Outcome measures will be assessed immediately after completion of IPAQ questionnaire (during study visit 2) ]
  • WSQ [ Time Frame: Outcome measures will be assessed immediately after completion of WSQ questionnaire (during study visit 2) ]
  • SF-12 [ Time Frame: Outcome measures will be assessed immediately after completion of SF-12 questionnaire (during study visit 2) ]

Central Contacts and Locations

Central contacts

Research Nurse

214-345-6574IEEMLung@TexasHealth.org

Abide Abulimiti, Ph.D.

214-345-6501Abidanabulimiti@TexasHealth.org

Locations

Institute for Exercise and Environmental Medicine, UT Southwestern and Texas Health Resources

Recruiting

Dallas, Texas, United States, 75231

Contacts

Raksa Moran, BSN

214-345-6574IEEMLung@texashealth.org

More Information

Sponsor

University of Texas Southwestern Medical Center

Last update posted

Sep 2, 2026

Last verified

Aug, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by University of Texas Southwestern Medical Center on 2026-09-02.