Actively Recruiting

Phase 4
Age: 18Years - 40Years
All Genders
Healthy Volunteers
NCT07424014

The Role of Heliox in Respiratory Control

Led by Indiana University · Updated on 2026-03-12

15

Participants Needed

1

Research Sites

68 weeks

Total Duration

On this page

Sponsors

I

Indiana University

Lead Sponsor

U

United States Department of Defense

Collaborating Sponsor

AI-Summary

What this Trial 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.

CONDITIONS

Official Title

The Role of Heliox in Respiratory Control

Who Can Participate

Age: 18Years - 40Years
All Genders
Healthy Volunteers

Eligibility Criteria

Eligible

You may qualify if you...

  • 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 with 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.
  • Body mass index (BMI) 4 35 kg/m2.
  • Females with a regular menstrual cycle ranging from 21-35 days (eumenorrhea).
Not Eligible

You will not qualify if you...

  • History of smoking or recreational smoking.
  • History of cardiovascular, renal, pulmonary (including asthma or exercise-induced asthma), neurological, or metabolic disease.
  • Pregnant or possibly pregnant by self-report.
  • Color blind.
  • Known allergy or hypersensitivity to latex.
  • Taking selective serotonin reuptake inhibitors, stimulant medication, antibiotics, or chronic pain medications.
  • Resting blood pressure over 130 mmHg systolic or 90 mmHg diastolic and/or resting pulse rate over 100 bpm.
  • Females with irregular menstrual cycles (36-90 days) or absence of menstrual cycle.
  • Taking birth control solely for period cessation (e.g., Mirena IUD).

AI-Screening

AI-Powered Screening

Complete this quick 3-step screening to check your eligibility

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Trial Site Locations

Total: 1 location

1

Multidisciplinary Engineering and Sciences Hall (MESH)

Bloomington, Indiana, United States, 47405

Actively Recruiting

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Research Team

T

Timothy D Mickleborough, PhD

CONTACT

How is the study designed?

Study Type

INTERVENTIONAL

Masking

NONE

Allocation

RANDOMIZED

Model

CROSSOVER

Primary Purpose

BASIC_SCIENCE

Number of Arms

2

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