NCT07216755 · Embry-Riddle Aeronautical University
Effects of Breathing Training and Nitrate on Exercise at Simulated Altitude
What this study is about
This study investigates whether respiratory muscle training (RMT) and dietary nitrate supplementation can improve exercise tolerance under simulated moderate altitude conditions. Exposure to reduced oxygen availability at altitude places additional strain on the cardiovascular and respiratory systems, which may limit endurance performance.
View original scientific description
This study investigates whether respiratory muscle training (RMT) and dietary nitrate supplementation can improve exercise tolerance under simulated moderate altitude conditions. Exposure to reduced oxygen availability at altitude places additional strain on the cardiovascular and respiratory systems, which may limit endurance performance. By combining RMT-designed to strengthen the muscles involved in breathing-with nitrate therapy, which enhances nitric oxide availability and vascular function, this study aims to determine whether these interventions independently or synergistically improve oxygen delivery, reduce physiological strain, and enhance exercise performance. The findings will help identify non-pharmacological strategies to improve physical performance and tolerance to hypoxia in both clinical and operational environments.
Interventions
DEVICE
Respiratory Muscle Training (RMT)
Participants perform supervised respiratory muscle training (RMT) using a handheld resistive breathing device designed to strengthen the inspiratory and expiratory muscles. Training sessions are conducted 5 days per week for approximately 4-6 weeks. Each session includes a series of resisted breathing maneuvers with progressively increased load as tolerated. The device is calibrated to maintain a constant pressure threshold to ensure consistent training intensity.
DEVICE
Sham Respiratory Muscle Training
Participants use an identical handheld breathing device with minimal resistance, providing no meaningful training stimulus. The training schedule and session duration match those of the active RMT group to maintain participant blinding.
DIETARY_SUPPLEMENT
Dietary Supplement: Beetroot Juice Concentrate
Participants consume a standardized dose of concentrated beetroot juice daily for the duration of the training period (approximately 4-6 weeks). The supplement provides a fixed quantity of dietary nitrate known to enhance nitric oxide availability and support vascular and metabolic function during exercise.
DIETARY_SUPPLEMENT
placebo beverage
Participants consume a placebo beverage identical in color, taste, and appearance to the nitrate supplement but containing no active nitrate. The beverage is consumed daily following the same schedule as the active supplement.
Primary outcome measures
Change in Exercise Tolerance at Simulated Altitude
Time frame: Baseline to Post-Intervention (approximately 4-6 weeks)
Exercise tolerance will be measured as the time to exhaustion during a graded cycling exercise test performed under simulated moderate altitude conditions (\~2,500-3,000 meters). Tests will be conducted before and after the 4-6 week intervention period. The measure reflects overall improvements in aerobic performance and fatigue resistance following respiratory muscle training, nitrate supplementation, or their combination.
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
- Healthy adults between 18 and 40 years old. Recreationally active (performing ≥3 hours of structured physical activity per week). Non-smokers for at least the past 6 months. Free from any known cardiovascular, pulmonary, metabolic, or neuromuscular disease as determined by health screening questionnaire and medical history. Able to perform cycle ergometer exercise to volitional fatigue. Willing to abstain from high-nitrate foods and supplements (e.g., beets, spinach, arugula) for 48 hours prior to each testing session. Able and willing to provide written informed consent and comply with all study procedures.
Exclusion criteria
- Diagnosis of or history of heart disease, hypertension, diabetes, or chronic respiratory disorders (e.g., asthma, COPD). Current use of medications or supplements known to affect cardiovascular, metabolic, or respiratory function (e.g., beta-blockers, nitrates, stimulants). Smoking, vaping, or tobacco use within the past 6 months. Known allergy or intolerance to beetroot products or nitrates. Participation in another interventional research study within the past 30 days. Pregnant or breastfeeding women. Any orthopedic or musculoskeletal limitation preventing safe exercise testing. Failure to meet inclusion criteria or inability to complete familiarization and baseline testing.
Where
- Daytona Beach, Florida
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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 Oct 15, 2025 · Source of record for eligibility and locations