Exercise Performance of Fit AthletesBEETNCT07501806
Effect of the Combination of Nitrate and Caffeine on Critical Power In Trained Male Cyclists
A study testing Dietary Nitrate and Caffeine in people with Exercise Performance of Fit Athletes and Exercise Performance, run by Lindenwood University at 1 site in United States.
Trial summary
This study is investigating the independent and combined effects of acute dietary nitrate and caffeine supplementation on performance during a 3-minute all-out cycling test in trained male cyclists. Read more about this study
- Who is it for?
- Ages 18 to 40 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Exercise Performance of Fit Athletes, Exercise Performance, Cycling Performance
- What is being tested?
- Dietary Nitrate and Caffeine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 15 participants
- Where
- 1 siteUnited States
- Study dates
- 17 Nov 2020to 11 Nov 2021
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Males between the ages of 18 and 40 years of age
- All participants must be trained cyclists, having participated in structured cycling training consisting of at least 2-3 sessions per week for at least 30-60 min each session during the past 12 months.
- All participants must possess a relative max power output (Wmax) of 4.0 W/kg or greater OR a maximal oxygen consumption (VO2max) of 50 ml/kg/min.
- All participants must be healthy and free of any disease as determined through the completion of a medical history questionnaire.
- Body mass index (BMI) between 18.5 - 30 kg/m^2 OR bodyfat percentage <30%
Who cannot join
- All females
- Males who are younger than 18 years and older than 40 years of age
- Individuals who have a VO2max below 50 ml/kg/min and a relative Wmax below 4.0 W/kg
- Individuals who fail to meet the minimum training requirements of 2-3 sessions per week of structured cycling training for at least 30-60 min per session during the past 12 months.
- Any individual currently diagnosed with or being treated for any cardiovascular, renal, pulmonary, orthopedic, immunological, psychological or musculoskeletal disorder.
- Any individual who is currently supplementing with a known or purported ergogenic aid (nitrates, caffeine, beta-alanine, bicarbonate, creative, Cordyceps) will be required to refrain from their use for 30 days before beginning the study.
- Individuals who regularly smoke or have quit smoking within the last 6 months.
Trial locations and contacts
1 site in 1 country.
United States1 site
Exercise and Performance Nutrition Laboratory
Saint Charles, Missouri, 63301
About this study
This study is investigating the independent and combined effects of acute dietary nitrate and caffeine supplementation on performance during a 3-minute all-out cycling test in trained male cyclists. In a randomized, double-blind, placebo-controlled, crossover design, participants will complete four experimental conditions: nitrate, caffeine, nitrate plus caffeine, and placebo. Primary outcomes include end power (EP) and work done above end power (WEP), surrogate measures of critical power and W'. The study aims to determine whether combined supplementation provides additive benefits for severe-intensity exercise performance.
Read the detailed description
Dietary nitrate and caffeine are among the most commonly used ergogenic aids in endurance and high-intensity exercise. Nitrate supplementation has been shown to improve exercise efficiency and tolerance to severe-intensity work, potentially through enhanced nitric oxide availability and improved oxygen delivery and utilization. Caffeine, primarily acting through central nervous system stimulation, has been associated with reduced perceived exertion and enhanced performance across a range of exercise modalities. Despite substantial evidence supporting their independent effects, limited research has examined the combined impact of nitrate and caffeine supplementation on exercise performance.
The present study aims to investigate both the independent and combined effects of acute dietary nitrate and caffeine supplementation on performance outcomes derived from a 3-minute all-out cycling test (3MT), a validated method for estimating critical power and W'. Trained male cyclists will complete four experimental trials in a randomized, double-blind, placebo-controlled, crossover design. Experimental conditions include nitrate-rich beetroot juice with caffeine (BR + CAF), nitrate-rich beetroot juice with placebo (BR), nitrate-depleted beetroot juice with caffeine (CAF), and nitrate-depleted beetroot juice with placebo (PLA).
Participants will consume dietary nitrate 3 hours prior to exercise and caffeine (5 mg/kg body mass) 60 minutes prior to testing. Following a standardized protocol, participants will perform a 3-minute all-out cycling test on an electronically braked cycle ergometer. Primary outcome measures include end power (EP) and work performed above end power (WEP), with secondary outcomes including peak power, mean power, and time-specific power output.
This study aims to determine whether co-ingestion of nitrate and caffeine produces additive or synergistic effects on severe-intensity exercise performance, and to evaluate the extent to which these commonly used ergogenic aids influence performance outcomes associated with critical power in trained individuals.
- Being tested
- Dietary Nitrate, Caffeine, Placebo
- Keywords
- dietary nitrate, caffeine, beetroot juice, critical power,, cycling, exercise physiology, ergogenic aids
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dietary NitrateDietary supplement
Participants consume concentrated nitrate-rich beetroot juice providing approximately 8.2 mmol of nitrate 3 hours prior to exercise.
CaffeineDietary supplement
Participants consume caffeine at a dose of 5 mg/kg body mass in capsule form 60 minutes prior to exercise.
PlaceboOther
Participants consume a nitrate-depleted beetroot juice placebo approximately 2-3 hours prior to exercise and a placebo capsule (maltodextrin) approximately 60 minutes prior to exercise.
| Study group | Role | What they receive |
|---|---|---|
| Nitrate + Caffeine (BR + CAF) | Experimental | Participants consume nitrate-rich beetroot juice 3 hours prior to exercise and caffeine 60 minutes prior to exercise. Receives: Dietary Supplement: Dietary Nitrate; Dietary Supplement: Caffeine |
| Nitrate Only (BR) | Experimental | Participants consume nitrate-rich beetroot juice 3 hours prior to exercise and placebo capsule 60 minutes prior to exercise. Receives: Dietary Supplement: Dietary Nitrate; Other: Placebo |
| Caffeine Only (CAF) | Experimental | Participants consume nitrate-depleted placebo 3 hours prior to exercise and caffeine 60 minutes prior to exercise. Receives: Dietary Supplement: Caffeine; Other: Placebo |
| Placebo (PLA) | Placebo comparator | Participants consume nitrate-depleted placebo 3 hours prior to exercise and placebo 60 minutes prior to exercise Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
End Power
End power (EP) will be determined as the average power output over the final 30 seconds of the 3-minute all-out cycling test and will be used as a surrogate measure of critical power.
Measured: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Work Above End Power
Work performed above end power (WEP) will be calculated as the total work completed above EP during the 3-minute all-out cycling test and will be used as a surrogate measure of W' (anaerobic work capacity).
Measured: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Secondary outcomes (2)
Peak Power Output
Peak power output will be defined as the highest instantaneous power output achieved during the 3-minute all-out cycling test.
Measured: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Mean Power Output
Mean power output will be calculated as the average power output across the entire 3-min all-out cycling test.
Measured: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Mar 2026
- Study start17 Nov 2020
- Primary completion11 Nov 2021
- Study completion11 Nov 2021
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Exercise Performance of Fit AthletesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- This study uses a randomized, double-blind, placebo-controlled, crossover design in which each participant completes four experimental conditions: nitrate supplementation (BR), caffeine supplementation (CAF), combined nitrate and caffeine supplementation (BR + CAF), and placebo (PLA). The order of conditions is randomized for each participant, and all participants complete all conditions with a washout period of at least 72 hours between trials.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- Lindenwood University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07501806
- Sponsor's protocol ID
- IRB-20-170
- Acronym
- BEET
- Status last verified
- Mar 2026
- First submitted
- 19 Mar 2026
- Last updated
- 30 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of the Combination of Nitrate and Caffeine on Critical Power In Trained Male Cyclists
- ClinicalTrials.gov ID
- NCT07501806
- Acronym / sponsor ID
- BEET / IRB-20-170
- Keywords
- dietary nitrate, caffeine, beetroot juice, critical power,, cycling, exercise physiology, ergogenic aids
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- Lindenwood UniversityUniversity, hospital or other
- Study start
- 17 Nov 2020 (actual)
- Primary completion
- 11 Nov 2021 (actual)
- Study completion
- 11 Nov 2021 (actual)
- First posted
- 30 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is investigating the independent and combined effects of acute dietary nitrate and caffeine supplementation on performance during a 3-minute all-out cycling test in trained male cyclists. In a randomized, double-blind, placebo-controlled, crossover design, participants will complete four experimental conditions: nitrate, caffeine, nitrate plus caffeine, and placebo. Primary outcomes include end power (EP) and work done above end power (WEP), surrogate measures of critical power and W'. The study aims to determine whether combined supplementation provides additive benefits for severe-intensity exercise performance.
Detailed description
Dietary nitrate and caffeine are among the most commonly used ergogenic aids in endurance and high-intensity exercise. Nitrate supplementation has been shown to improve exercise efficiency and tolerance to severe-intensity work, potentially through enhanced nitric oxide availability and improved oxygen delivery and utilization. Caffeine, primarily acting through central nervous system stimulation, has been associated with reduced perceived exertion and enhanced performance across a range of exercise modalities. Despite substantial evidence supporting their independent effects, limited research has examined the combined impact of nitrate and caffeine supplementation on exercise performance.
The present study aims to investigate both the independent and combined effects of acute dietary nitrate and caffeine supplementation on performance outcomes derived from a 3-minute all-out cycling test (3MT), a validated method for estimating critical power and W'. Trained male cyclists will complete four experimental trials in a randomized, double-blind, placebo-controlled, crossover design. Experimental conditions include nitrate-rich beetroot juice with caffeine (BR + CAF), nitrate-rich beetroot juice with placebo (BR), nitrate-depleted beetroot juice with caffeine (CAF), and nitrate-depleted beetroot juice with placebo (PLA).
Participants will consume dietary nitrate 3 hours prior to exercise and caffeine (5 mg/kg body mass) 60 minutes prior to testing. Following a standardized protocol, participants will perform a 3-minute all-out cycling test on an electronically braked cycle ergometer. Primary outcome measures include end power (EP) and work performed above end power (WEP), with secondary outcomes including peak power, mean power, and time-specific power output.
This study aims to determine whether co-ingestion of nitrate and caffeine produces additive or synergistic effects on severe-intensity exercise performance, and to evaluate the extent to which these commonly used ergogenic aids influence performance outcomes associated with critical power in trained individuals.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 4
- Model description
- This study uses a randomized, double-blind, placebo-controlled, crossover design in which each participant completes four experimental conditions: nitrate supplementation (BR), caffeine supplementation (CAF), combined nitrate and caffeine supplementation (BR + CAF), and placebo (PLA). The order of conditions is randomized for each participant, and all participants complete all conditions with a washout period of at least 72 hours between trials.
| Arm | Type | Receives |
|---|---|---|
| Nitrate + Caffeine (BR + CAF) | Experimental | Dietary Supplement: Dietary Nitrate, Dietary Supplement: CaffeineParticipants consume nitrate-rich beetroot juice 3 hours prior to exercise and caffeine 60 minutes prior to exercise. |
| Nitrate Only (BR) | Experimental | Dietary Supplement: Dietary Nitrate, Other: PlaceboParticipants consume nitrate-rich beetroot juice 3 hours prior to exercise and placebo capsule 60 minutes prior to exercise. |
| Caffeine Only (CAF) | Experimental | Dietary Supplement: Caffeine, Other: PlaceboParticipants consume nitrate-depleted placebo 3 hours prior to exercise and caffeine 60 minutes prior to exercise. |
| Placebo (PLA) | Placebo comparator | Other: PlaceboParticipants consume nitrate-depleted placebo 3 hours prior to exercise and placebo 60 minutes prior to exercise |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Males between the ages of 18 and 40 years of age
- All participants must be trained cyclists, having participated in structured cycling training consisting of at least 2-3 sessions per week for at least 30-60 min each session during the past 12 months.
- All participants must possess a relative max power output (Wmax) of 4.0 W/kg or greater OR a maximal oxygen consumption (VO2max) of 50 ml/kg/min.
- All participants must be healthy and free of any disease as determined through the completion of a medical history questionnaire.
- Body mass index (BMI) between 18.5 - 30 kg/m^2 OR bodyfat percentage <30%
Key exclusion criteria (7 listed)
- All females
- Males who are younger than 18 years and older than 40 years of age
- Individuals who have a VO2max below 50 ml/kg/min and a relative Wmax below 4.0 W/kg
- Individuals who fail to meet the minimum training requirements of 2-3 sessions per week of structured cycling training for at least 30-60 min per session during the past 12 months.
- Any individual currently diagnosed with or being treated for any cardiovascular, renal, pulmonary, orthopedic, immunological, psychological or musculoskeletal disorder.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dietary NitrateParticipants consume concentrated nitrate-rich beetroot juice providing approximately 8.2 mmol of nitrate 3 hours prior to exercise. | Dietary supplement | Nitrate + Caffeine (BR + CAF), Nitrate Only (BR) |
| CaffeineParticipants consume caffeine at a dose of 5 mg/kg body mass in capsule form 60 minutes prior to exercise. | Dietary supplement | Caffeine Only (CAF), Nitrate + Caffeine (BR + CAF) |
| PlaceboParticipants consume a nitrate-depleted beetroot juice placebo approximately 2-3 hours prior to exercise and a placebo capsule (maltodextrin) approximately 60 minutes prior to exercise. | Other | Caffeine Only (CAF), Nitrate Only (BR), Placebo (PLA) |
Primary outcome
End Power
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
End power (EP) will be determined as the average power output over the final 30 seconds of the 3-minute all-out cycling test and will be used as a surrogate measure of critical power.
Work Above End Power
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Work performed above end power (WEP) will be calculated as the total work completed above EP during the 3-minute all-out cycling test and will be used as a surrogate measure of W' (anaerobic work capacity).
2 secondary outcomes
Peak Power Output
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Mean Power Output
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Mar 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Dietary Nitrate and Caffeine in people with Exercise Performance of Fit Athletes and Exercise Performance, run by Lindenwood University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 30 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
End Power (time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Mar 2026.