Caffeine and Pepper in Running

Caffeine and capsaicin supplementation during running.

Status

Recruiting

Phases

Unknown

Study type

Interventional

Source

REBEC

Registry ID

RBR-46vfxj2

Enrollment

Registered

2026-06-11

Start date

2026-05-25

Completion date

Unknown

Last updated

2026-06-22

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

Conditions

Running Dietary Supplements

Interventions

This is a randomized, crossover, double-blind, placebo-controlled clinical trial designed to investigate the acute effects of caffeine supplementation (CAF), a substance with well-established ergogeni

Eligibility

Age

18 Years to 35 Years

Inclusion criteria

Inclusion criteria: Runners aged 18 to 35; both sexes; runners who do not have joint, muscle, or bone injuries that could interfere with their performance; have been running for 12 consecutive months or more; have participated in a race of 10 kilometers or more in the last 12 months; and must run one kilometer in less than six minutes (pace less than 6 min/km) during a 10-kilometer time trial

Exclusion criteria

Exclusion criteria: Participants who develop of joint, muscular, or bone injuries capable of affecting performance during the experimental period; failure to comply with study instructions; use of non-authorized ergogenic substances during the study period; failure to complete all assessments included in the protocol; voluntary withdrawal from the study

Design outcomes

Primary

Measure	Time frame
A difference in 10 km running performance is expected between the placebo and caffeine experimental conditions. The assessment will be conducted using a time trial on an official 400-meter athletics track, in which volunteers will run 25 consecutive laps in a single lane in the shortest possible time, under the supervision of researchers to ensure standardization and safety during all experimental sessions. The parameters used to verify the outcome will include the total test completion time, measured in seconds with a Casio HS-3 stopwatch, the average speed, calculated by the ratio between the total distance covered and the total test time, as well as the decay of average speed throughout the test, obtained from the times recorded on the 5th, 10th, 15th, 20th, and 25th laps, allowing for comparison between the placebo and caffeine conditions.	—

Measure

Time frame

A difference in 10 km running performance is expected between the placebo and caffeine experimental conditions. The assessment will be conducted using a time trial on an official 400-meter athletics track, in which volunteers will run 25 consecutive laps in a single lane in the shortest possible time, under the supervision of researchers to ensure standardization and safety during all experimental sessions. The parameters used to verify the outcome will include the total test completion time, measured in seconds with a Casio HS-3 stopwatch, the average speed, calculated by the ratio between the total distance covered and the total test time, as well as the decay of average speed throughout the test, obtained from the times recorded on the 5th, 10th, 15th, 20th, and 25th laps, allowing for comparison between the placebo and caffeine conditions.

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Secondary

Measure	Time frame
Are expected to be observed in response to the exertion imposed by the 10 km time trial test, as an indicator of the internal load of the exercise. This will be verified by measuring blood lactate before and after the test in all experimental sessions. The evaluation will be performed by collecting 2 microliters of blood from the index finger of the volunteers, obtained by finger prick with a disposable lancet, with immediate transfer of the sample to a reagent strip and subsequent analysis in a portable lactate analyzer. The parameters used to verify the occurrence of the outcome will include lactate concentrations expressed in mmol/L at the pre- and post-test times, allowing comparison between the different experimental sessions. The entire procedure will follow the guidelines of the National Health Council, including local sanitization with 70% alcohol before collection and disposal of lancets in an appropriate sharps container.;It is expected that the subjective perception of effort will be modified by caffeine supplementation compared to placebo, due to its potential effects on central fatigue, resulting in less perceived effort during exercise. Verification of this outcome will be performed using the subjective perception of effort scale, a psychophysical variable influenced by muscular, articular, central nervous system, cardiovascular, and respiratory signals, using the Gunnar Borg scale from 6 to 20 points. Data will be collected at the end of the last lap of each 10 km time trial, using a standardized question asked by the evaluator about the perception of effort during the exercise session. The parameters used to verify the outcome will include the absolute variation of the scores obtained on the scale, allowing comparison between placebo and caffeine conditions, where values ??closer to 6 indicate very easy effort and values ??closer to 20 indicate exhaustive effort.;It is expected that the subjective perception of effort during the session will be influ	—

Measure

Time frame

Are expected to be observed in response to the exertion imposed by the 10 km time trial test, as an indicator of the internal load of the exercise. This will be verified by measuring blood lactate before and after the test in all experimental sessions. The evaluation will be performed by collecting 2 microliters of blood from the index finger of the volunteers, obtained by finger prick with a disposable lancet, with immediate transfer of the sample to a reagent strip and subsequent analysis in a portable lactate analyzer. The parameters used to verify the occurrence of the outcome will include lactate concentrations expressed in mmol/L at the pre- and post-test times, allowing comparison between the different experimental sessions. The entire procedure will follow the guidelines of the National Health Council, including local sanitization with 70% alcohol before collection and disposal of lancets in an appropriate sharps container.;It is expected that the subjective perception of effort will be modified by caffeine supplementation compared to placebo, due to its potential effects on central fatigue, resulting in less perceived effort during exercise. Verification of this outcome will be performed using the subjective perception of effort scale, a psychophysical variable influenced by muscular, articular, central nervous system, cardiovascular, and respiratory signals, using the Gunnar Borg scale from 6 to 20 points. Data will be collected at the end of the last lap of each 10 km time trial, using a standardized question asked by the evaluator about the perception of effort during the exercise session. The parameters used to verify the outcome will include the absolute variation of the scores obtained on the scale, allowing comparison between placebo and caffeine conditions, where values ??closer to 6 indicate very easy effort and values ??closer to 20 indicate exhaustive effort.;It is expected that the subjective perception of effort during the session will be influ

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Countries

Contacts

Public ContactMarcos Daniel Drummond

Universidade Federal de Minas Gerais

mierciosoares@gmail.com+55-31-992165726

Outcome results

None listed

Source: REBEC (via WHO ICTRP) · Data processed: Jun 29, 2026