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RecruitingAccepts healthy volunteersPhase 4

The Role of Heliox in Respiratory Control

Indiana University · with United States Department of Defense · NCT07424014

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Opens the official ClinicalTrials.gov record, with the study team’s contacts. Bored Studies doesn’t enroll anyone.

Key facts

Compensation
Not posted. Ask the study team before screening.
Who can join
Ages 18–40 · All sexes
Healthy volunteers
Accepted
Study type
Interventional · Phase 4
Target enrollment
15
US sites recruiting
1
Study start
February 3, 2026
Record last updated
March 12, 2026

Status re-checked against ClinicalTrials.gov within the last 12 hours.

What the study is about

Warfighters are frequently exposed to environments and life-support systems that increase breathing resistance and the work of breathing (WOB), such as aircraft on-board oxygen generation systems and underwater breathing apparatuses. Elevated WOB increases the perception of breathing difficulty (dyspnea) and has been associated with impaired cognitive performance, including slower reaction time and reduced accuracy during attention-demanding tasks. These effects are particularly concerning in operational settings that require rapid decision-making and precise motor responses.

Despite growing recognition of this issue, critical gaps remain regarding strategies to mitigate the perceptual and cognitive consequences of elevated inspiratory resistance, especially under realistic operational stressors. The objective of this study is to determine whether reducing mechanical WOB alters breathing perception and cognitive performance during inspiratory resistance. Participants will breathe either normal-density air or a low-density helium-oxygen gas mixture (heliox) to determine whether reducing mechanical WOB lowers perceived breathing effort and improves cognitive function.

Being studied: Heliox inspirate

Conditions: Work of Breathing

Eligibility criteria

Copied from the official record. The study team makes the final decision at screening.

Show full 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)

Recruiting US locations

  • Multidisciplinary Engineering and Sciences Hall (MESH)

    Bloomington, IN 47405

    Site contact: Scott M Clarke · 812-856-3244 · scotclar@iu.edu

Study contacts (from the official record)

  • Timothy D Mickleborough, PhD · 812-855-0753 · tmickleb@iu.edu
All healthy volunteers studies in Indiana →
The Role of Heliox in Respiratory Control (NCT07424014) | Bored Studies