NCT05028309 · University of Texas Southwestern Medical Center
Effects of Obesity in the Aged
What this study is about
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.
View original scientific description
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.
Interventions
OTHER
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 measures
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)
Pulmonary function is comprised of several physiological variables but this study will primarily measure Lung Volume: FRC (liters) and TLC (liters)
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).
Exercise Tolerance is represented by several physiological variables but the primary variable is Maximal oxygen uptake (L/min and percent predicted)
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).
Dyspnea on Exertion is represented using the Borg Scale which provides Ratings of Perceived Breathlessness (RPB) during constant load exercise cycling. The Borg Scale measures from 0-10, where 0 = no breathlessness and 10 = maximal breathlessness.
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).
Positive and Negative Affect Schedule. This scale consists of a number of words that describe different feelings and emotions.
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)
Investigate the qualities of respiratory sensations (e.g., "effort of breathing", "breathing heavy", "breathing shallow") during exercise before and after mechanical unloading of the chest wall
Dyspnoea-12
Time frame: Outcome measures will be assessed immediately after completion of Dyspnoea-12 questionnaire (during study visit 2)
This questionnaire is designed to help us learn more about how their breathing is troubling them.
ASI
Time frame: Outcome measures will be assessed immediately after completion of ASI questionnaire (during study visit 2)
The Anxiety Sensitivity Index (ASI) is a 16 item scale containing items specifying different concerns someone could have regarding their anxiety.
HADS
Time frame: Outcome measures will be assessed immediately after completion of HADS questionnaire (during study visit 2)
HADS (Hospital Anxiety and Depression Scale) aims to measure symptoms of anxiety (HADS Anxiety) and depression (HADS Depression). HADS score: 0-7 = normal; 8-10 = mild; 11-14 = moderate; 15-21 = severe
SDS-MC
Time frame: Outcome measures will be assessed immediately after completion of MC-SDS questionnaire (during study visit 2)
The Marlowe-Crowne Social Desirability Scale (MC-SDS) is a 33-item self-report questionnaire that assesses whether or not respondents are concerned with social approval.
IPAQ
Time frame: Outcome measures will be assessed immediately after completion of IPAQ questionnaire (during study visit 2)
International Physical Activity Questionnaires (IPAQ) is a 27-item self-reported measure of physical activity
WSQ
Time frame: Outcome measures will be assessed immediately after completion of WSQ questionnaire (during study visit 2)
Workforce Sitting Questionnaire (WSQ) is to estimate how much time they usually spend sitting in each of the following activities on a working day and a non-working day.
SF-12
Time frame: Outcome measures will be assessed immediately after completion of SF-12 questionnaire (during study visit 2)
SF-12 is a health-related quality-of-life questionnaire
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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.
Where
- Dallas, Texas
Collaborators
National Institute on Aging (NIA)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 28, 2025 · Source of record for eligibility and locations