Effects of Breathing Training and Nitrate on Exercise at Simulated Altitude
Impact of Respiratory Muscle Training and Nitrate Therapy on Exercise Tolerance in Simulated Altitude
Embry-Riddle Aeronautical University
80 participants
Sep 1, 2025
INTERVENTIONAL
Conditions
Summary
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.
Eligibility
Inclusion Criteria7
- 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 Criteria7
- 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.
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Interventions
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.
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.
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.
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.
Locations(1)
View Full Details on ClinicalTrials.gov
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NCT07216755