Physiological Responses to Sprint Interval Exercise Under Hypoxic Conditions in Trained Cyclists

Effects of Inter-effort Recovery Intermittent Hypoxia on Nitrate and Nitrite Bioavailability, Endothelial Function, Muscle Oxygenation, and Exercise Tolerance during Sprint Interval Training

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

REBEC

Registry ID

RBR-3sfstb5

Enrollment

Registered

2026-05-06

Start date

2026-06-01

Completion date

Unknown

Last updated

2026-06-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Physiological responses, physical fitness, and exercise performance in trained cyclists exposed to sprint interval exercise under normoxic and hypoxic conditions Musculoskeletal and Neural Physiological Phenomena

Interventions

This is a randomized, crossover, controlled, double-blind study with 3 arms, conducted with 15 trained male cyclists aged 18 to 45 years. The experimental design comprises three sprint interval traini

Eligibility

Sex/Gender

Male

Age

18 Years to 45 Years

Inclusion criteria

Inclusion criteria: Male individuals; aged between 18 and 45 years; cyclists; born and residing at low altitude locations

Exclusion criteria

Exclusion criteria: History of metabolic or cardiovascular diseases; recent diagnosis of anemia; recent exposure to normobaric or hypobaric hypoxia; recent muscular injury; use of vasodilating foods or supplements

Design outcomes

Primary

Measure	Time frame
To assess endothelial function, verified by the flow-mediated dilation method, through the observation of the percentage of brachial artery dilation after the hyperemic stimulus; to assess muscle oxygenation, verified by the near-infrared spectroscopy method, through the observation of oxyhemoglobin, deoxyhemoglobin, total hemoglobin concentrations, and tissue saturation index; to assess the plasma bioavailability of nitric oxide metabolites, verified by laboratory biochemical analysis, through the observation of plasma nitrate, nitrite, and nitrosylated species concentrations; to assess physical performance during the sprint interval training protocol, verified through the measurement of peak power, mean power, minimum power, and fatigue index	—

Measure

Time frame

To assess endothelial function, verified by the flow-mediated dilation method, through the observation of the percentage of brachial artery dilation after the hyperemic stimulus; to assess muscle oxygenation, verified by the near-infrared spectroscopy method, through the observation of oxyhemoglobin, deoxyhemoglobin, total hemoglobin concentrations, and tissue saturation index; to assess the plasma bioavailability of nitric oxide metabolites, verified by laboratory biochemical analysis, through the observation of plasma nitrate, nitrite, and nitrosylated species concentrations; to assess physical performance during the sprint interval training protocol, verified through the measurement of peak power, mean power, minimum power, and fatigue index

—

Secondary

Measure	Time frame
To assess rating of perceived exertion, verified through a subjective exertion scale, by observing the scores assigned by the participants during the exercise protocols; to assess aerobic and anaerobic metabolic contribution, verified through the analysis of gas exchange and blood lactate concentrations, by observing the aerobic, anaerobic lactic, and anaerobic alactic energy contributions during the exercise protocols; to assess performance in the maximal test until voluntary exhaustion, verified through the measurement of total exercise time until voluntary interruption, by observing the time limit achieved by the participants	—

Measure

Time frame

To assess rating of perceived exertion, verified through a subjective exertion scale, by observing the scores assigned by the participants during the exercise protocols; to assess aerobic and anaerobic metabolic contribution, verified through the analysis of gas exchange and blood lactate concentrations, by observing the aerobic, anaerobic lactic, and anaerobic alactic energy contributions during the exercise protocols; to assess performance in the maximal test until voluntary exhaustion, verified through the measurement of total exercise time until voluntary interruption, by observing the time limit achieved by the participants

—

Countries

Contacts

Public ContactFelipe Ribeiro

Universidade de São Paulo

felipe.alves.ribeiro@usp.br+55(16)993402517

Outcome results

None listed

Source: REBEC (via WHO ICTRP) · Data processed: Jun 11, 2026