Heliox to ease breathing and sharpen thinking when breathing is hard

Optimizing Mind-Body Interactions in Respiratory Control During Operationally Relevant Environmental Stressors

This trial will test whether breathing heliox (a low-density gas mix) reduces breathing effort and improves reaction time and accuracy in healthy adults exposed to increased inspiratory resistance.

Quick facts

• Phase: Phase 4
• Study type: Interventional
• Enrollment: 15 (estimated)
• Ages: 18 Years to 40 Years
• Sex: All
• Sponsor: Indiana University (Academic / other)
• Locations: 1 site (Bloomington, Indiana)
• Trial ID: NCT07424014 on ClinicalTrials.gov

What this trial studies

This interventional Phase 4 trial enrolls healthy, physically active adults aged 18–40 with normal lung and cognitive function to compare heliox versus normal-density air during controlled inspiratory resistance. Participants complete a screening/familiarization visit and a main experimental visit where they perform attention-demanding reaction-time tasks and report breathing perception while breathing under elevated inspiratory loads. Heliox is used because its low density reduces turbulent airway flow and the resistive work of breathing, allowing the study to isolate whether lowering mechanical load improves cognitive performance and reduces dyspnea. Outcomes include measures of perceived breathing effort, reaction time, accuracy, and lung mechanics.

Who should consider this trial

Good fit: Ideal participants are healthy, English-speaking adults aged 18–40 who are regularly active (≥120 minutes/week high-intensity exercise), with normal pulmonary and cognitive test results and BMI ≤35 kg/m2.

Not a fit: People with chronic lung, cardiovascular, renal, neurological, or metabolic disease, smokers, pregnant individuals, those on excluded medications, or those with abnormal lung or cognitive screening are not eligible and are unlikely to benefit from the findings.

Why it matters

Potential benefit: If successful, the approach could reduce breathing discomfort and improve cognitive performance during high-resistance breathing situations, potentially improving operational performance for Warfighters.

How similar studies have performed: Prior physiological and clinical work shows heliox lowers resistive work of breathing, but its direct effects on cognitive performance during inspiratory resistance have been less well studied.

Eligibility criteria

Inclusion Criteria:

* Between the ages of 18-40 years old.
* English speaking and reading.
* Self-reported weekly activity of at least 120 minutes/week of high intensity exercise for the previous 2 years.
* Normal pulmonary function assessed by a resting forced expiratory volume in 1 second over forced vital capacity (FEV1/FVC) \> 75% of predicted.
* Normal cognitive function assessed using the Montreal cognitive function test \[18\].
* Body mass index (BMI) ≤ 35 kg/m2.
* Females with a regular menstrual cycle that ranges from 21-35 days (eumenorrhea)

Exclusion Criteria:

* History of smoking or recreational smoking, cardiovascular disease, renal disease, pulmonary disease (including asthma or exercise-induced asthma), neurological disease, and metabolic disease.
* Are pregnant or could possibly be pregnant by self-report.
* Are color blind.
* Known allergy or hypersensitivity latex.
* Take selective serotonin reuptake inhibitors, stimulant medication, antibiotics, and chronically consume pain medication (Aleve, Tylenol, etc.).
* Resting blood pressure of \> 130mmHg systolic or 90 mmHg diastolic and/or resting pulse rate of \> 100 bpm.
* Females with irregular menstrual cycles (oligomenorrhea) that ranges from 36-90 days, and females with the absence of a menstrual cycle (amenorrhea).
* Taking birth control for the sole purpose of period cessation (eg., Mirena IUD)

Where this trial is running

Bloomington, Indiana

• Multidisciplinary Engineering and Sciences Hall (MESH) — Bloomington, Indiana, United States (Recruiting)

Study contacts

• Study coordinator: Timothy D Mickleborough, PhD

Conditions Work of Breathing; Inspiratory Resistance; Dyspnea Perception; Cognitive Performance