The effect of acute caffeine and capsaicin supplementation on performance and psychophysiological variables

Caffeine and capsaicin supplementation during running

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

REBEC

Registry ID

RBR-8jvkfdc

Enrollment

Registered

2026-02-26

Start date

2026-01-26

Completion date

Unknown

Last updated

2026-03-02

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

Conditions

Running

Interventions

This is a randomized, double-blind, placebo-controlled clinical trial that will investigate caffeine (CAF) and capsaicin (CAP) supplementation, substances with ergogenic properties and the ability to

CAP

CAF+CAP and Placebo). During the experimental sessions, the following performance variables will be evaluated: total time to complete the 10km time trial, average pace, and pace decay throughout the r

Eligibility

Age

18 Years to 45 Years

Inclusion criteria

Inclusion criteria: As an inclusion criterion, all runners who do not have joint, muscle, or bone injuries that could interfere with their performance will be accepted into the sample. In addition, they must have been running for 12 consecutive months or more, and have participated in a race with a distance of 10 kilometers or more in the last 12 months.

Exclusion criteria

Exclusion criteria: As an exclusion criterion, all volunteers who present with injuries capable of interfering with their performance during the experiment will be excluded from the sample.

Design outcomes

Primary

Measure	Time frame
It is expected that there will be a difference in 10 km running performance between the experimental conditions, assessed through a time trial test conducted 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. Performance will be verified using the measurement of the total running time timed in seconds with a Casio HS-3 stopwatch, with the values ??being compared between all experimental sessions. Additionally, the average speed will be calculated using the equation total distance divided by total time, as well as the decay of average speed throughout the test based on the times recorded in the 5th, 10th, 15th, 20th, and 25th laps, allowing for the evaluation of fatigue and maintenance of performance throughout the time trial.	—

Measure

Time frame

It is expected that there will be a difference in 10 km running performance between the experimental conditions, assessed through a time trial test conducted 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. Performance will be verified using the measurement of the total running time timed in seconds with a Casio HS-3 stopwatch, with the values ??being compared between all experimental sessions. Additionally, the average speed will be calculated using the equation total distance divided by total time, as well as the decay of average speed throughout the test based on the times recorded in the 5th, 10th, 15th, 20th, and 25th laps, allowing for the evaluation of fatigue and maintenance of performance throughout the time trial.

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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 and capsaicin supplementation, alone or in combination, due to their potential effects on central fatigue and pain modulation, resulting in less perceived effort during exercise. Verification of this outcome will be carried out using the subjective perception of effort scale, a psychophysical variable influenced by muscular, articular, central nervous system, cardiovascular, and respiratory signals, using the 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 how the exercise session went. It will be observed whether there is a reduction in the subjective perception of effort values ??between the different experimental conditions, considering the absolute variation of the scores on the scale, where values ??closer to 6 indicate very easy effort and values ??closer to 20 indicate exhaustive effort.;It is expected that the subjective perceptio	—

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 and capsaicin supplementation, alone or in combination, due to their potential effects on central fatigue and pain modulation, resulting in less perceived effort during exercise. Verification of this outcome will be carried out using the subjective perception of effort scale, a psychophysical variable influenced by muscular, articular, central nervous system, cardiovascular, and respiratory signals, using the 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 how the exercise session went. It will be observed whether there is a reduction in the subjective perception of effort values ??between the different experimental conditions, considering the absolute variation of the scores on the scale, where values ??closer to 6 indicate very easy effort and values ??closer to 20 indicate exhaustive effort.;It is expected that the subjective perceptio

—

Countries

Brazil

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: Mar 14, 2026