An interventional study of Dietary Nitrate and Caffeine in Exercise Performance of Fit Athletes, Exercise Performance and Cycling Performance, sponsored by Lindenwood University. Completed at 1 site in United States. Open to male participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-30.
Sponsored by Lindenwood University · Not applicable, Interventional, and Basic science
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.
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.
Lindenwood University is the lead sponsor of 29 studies on the registry; 6 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Participants consume nitrate-rich beetroot juice 3 hours prior to exercise and caffeine 60 minutes prior to exercise.
Dietary Supplement: Dietary Nitrate · Dietary Supplement: Caffeine
Participants consume nitrate-rich beetroot juice 3 hours prior to exercise and placebo capsule 60 minutes prior to exercise.
Dietary Supplement: Dietary Nitrate · Other: Placebo
Participants consume nitrate-depleted placebo 3 hours prior to exercise and caffeine 60 minutes prior to exercise.
Dietary Supplement: Caffeine · Other: Placebo
Participants consume nitrate-depleted placebo 3 hours prior to exercise and placebo 60 minutes prior to exercise
Other: Placebo
Participants consume concentrated nitrate-rich beetroot juice providing approximately 8.2 mmol of nitrate 3 hours prior to exercise.
Participants consume caffeine at a dose of 5 mg/kg body mass in capsule form 60 minutes prior to exercise.
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.
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.
Time frame: 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).
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Peak Power Output
Peak power output will be defined as the highest instantaneous power output achieved during the 3-minute all-out cycling test.
Time frame: 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.
Time frame: Assessed during a single 3-minute all-out cycling test, approximately 3 hours following supplementation
Plan to share: No
No publications or documents are linked to this record.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Lindenwood University