Recruiting

Lung Diffusing Capacity

Sponsor:

University of Alberta

Code:

NCT07897357

Conditions

Trained Athletes

Untrained

Eligibility Criteria

Sex: All

Age: 18 - 40

Healthy Volunteers: Accepted

Interventions

Lower body positive and negative pressure

Study Details

Brief summary:

Research shows that how well oxygen moves from the lungs into the blood (called lung diffusing capacity) is linked to a person's aerobic fitness and endurance training. People who exercise regularly often have different lung and heart responses than people who do not. The exact reasons for these differences are still unclear. This study will test one possible explanation: highly trained people may handle changes in the amount of blood returning to the heart differently than people who are not trained. We want to learn how the blood vessels in the lungs react when the amount of blood entering the heart changes, and how this reaction is affected by fitness level. To do this, we will change how much blood returns to the heart by applying air pressure around the legs, similar to a light vacuum. These changes are expected to be similar to what happens when someone moves from lying down to standing up.

Conditions

Trained Athletes

Untrained

Study ID

NCT07897357

Start date

Oct 9, 2026

Status verified date

Oct, 2026

Completion date

Jun 1, 2028

Anticipated

Primary completion date

Dec 15, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 40

Healthy Volunteers: Accepted

Inclusion Criteria:

  • 18-40 years old.

Exclusion Criteria:

  • Severe obesity (body mass index >35 kg/m2).
  • Self-reported blood donation or transfusion in the past 60 days. Large artificial fluctuations in blood volume may impact the findings of the present study.
  • Pregnancy. To confirm this, women not using contraception will be given a pregnancy test. Pregnancy presents additional complications and may confound the results of the study; therefore, pregnant women will be excluded.
  • Known chronic disease (heart failure, hypertension, diabetes, asthma, chronic obstructive pulmonary disease, renal disease).
  • Participants with known postural orthostatic tachycardic syndrome or orthostatic hypotension.
  • Participants who currently smoke cigarettes (within the last month) or those who have >1 pack-year smoking history.
  • Participants who currently smoke cannabis products (within the last month) or those who have >1 joint-year cannabis history.

Study Design

Enrollment

200 participants

Anticipated

Intervention Model

Single group

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: All participants

All participants complete all five visits as outlined in the study description.

Interventions

Lower body positive and negative pressure

Graded lower body positive pressure (+10, +20, +30 mmHg) and negative pressure (-15, -30, -45, -60 mmHg).

Primary outcome measure

  • Change in diffusing capacity for carbon monoxide (DLCO) [ Time Frame: Days 2 and 3. Measurements will be taken during each stage of intervention (e.g., LBPP/LBNP), after a minimum of 2 minutes from the onset of each stage. ]
  • Change in capillary blood volume (Vc) [ Time Frame: Days 2 and 3. Measurements will be taken during each stage of intervention (e.g., LBPP/LBNP), after a minimum of 2 minutes from the onset of each stage. ]
  • Change in membrane diffusing capacity (Dm) [ Time Frame: Days 2 and 3. Measurements will be taken during each stage of intervention (e.g., LBPP/LBNP), after a minimum of 2 minutes from the onset of each stage. ]

Central Contacts and Locations

Central contacts

Desi P Fuhr, MSc

780-492-1121fuhr@ualberta.ca

Locations

Clinical Physiology Laboratory

Recruiting

Edmonton, Alberta, Canada, T6G 2R3

Contacts

Desi P Fuhr, MSc

780-492-1121fuhr@ualberta.ca

Michael K Stickland, PhD

780-492-3995michael.stickland@ualberta.ca

More Information

Sponsor

University of Alberta

Last update posted

Oct 27, 2026

Last verified

Oct, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-28. This information was provided to ClinicalTrials.gov by University of Alberta on 2026-10-27. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.