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NCT Number: NCT07742150

Placebo Effect in Field-Based Physical Performance

This study aims to investigate the placebo (PLA) effect on physical performance across different sports disciplines in real-world, field-based settings. The study investigates how participant expectations and beliefs regarding caffeine (CAF) intake influence physical performance and psychomotor function outside the controlled laboratory environment. Healthy, physically active adults (n = 120) from diverse sports backgrounds will be randomly assigned to receive caffeine, placebo, or no intervention. Participants will perform discipline-specific field exercise tests (e.g., running-based protocols or repeated sprint protocols) while physiological responses are monitored using wearable technology. Physical performance outcomes and psychomotor responses will be analyzed to evaluate the real-world impact of the placebo effect and to distinguish the pharmacological effects of caffeine from those driven by psychological expectations across different athletic settings.

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Key information

Conditions

Physical Performance Cognitive Performance Placebo Effect

Age range

20 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Poznan University of Physical Education

Poznan, Greater Poland Voivodeship, Poland

Location contact

Jakub Malik, PhD

CONTACT

[email protected]

+48739975701

About this study

This study employs a cross-sectional design conducted in diverse field settings to investigate the placebo (PLA) effect across different sports disciplines. Participants (n = 120, aged 20-35 years) representing different training profiles (endurance and mixed) will be randomly assigned to one of three parallel groups: Caffeine, Placebo, or Control. Each participant will complete a single experimental session lasting approximately 35 minutes, consisting of: (1) baseline psychomotor assessment using the Simple Reaction Time test, (2) a discipline-specific exercise protocol (e.g., the Cooper test performed on an athletics track or a Repeated Sprint Ability protocol), and (3) post-exercise recovery monitoring. Physiological parameters, including heart rate (HR), heart rate variability (HRV), and respiratory rate (RR), together with postural stability, will be continuously monitored using wearable technology. The study will evaluate how psychological expectations influence physical performance, psychomotor function, and physiological responses during sport-specific exercise, providing evidence for the role of the placebo effect under real-world athletic conditions.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age between 20 and 35 years,
  • Healthy adults,
  • Regular physical activity,
  • Normal or corrected-to-normal vision,
  • Habitual caffeine consumption.

Exclusion criteria

  • History of neurological, psychiatric, cardiovascular, or metabolic disorders,
  • Current use of medication or supplements affecting the central nervous system,
  • Musculoskeletal injuries that would impair physical performance,
  • No habitual caffeine consumption or severe negative side effects of caffeine,
  • Diagnosed sleep disorders or chronic fatigue,
  • Diagnosed major depressive disorder or other severe psychiatric conditions,
  • Presence of any menstrual disorders,
  • Inability to attend all experimental study visits.

Treatment and study plan

Caffeine (6mg/kg)

Drug

Anhydrous caffeine administered in an encapsulated form at a dosage of 6mg per kilogram of body mass, 30-60 minutes before the exercise protocol.

Placebo (Starch capsule)

Other

Corn starch administered in an identical encapsulated form as the active caffeine, 30-60 minutes before the exercise protocol.

Sham (No Treatment)

Other

Participants perform the same exercise protocols without any capsule or substance administration.

Primary outcomes

  1. Physical Performance Capacity (total distance in running, metres)

    Time frame: Measured during the exercise protocol immediately following administration of the study intervention.

    Total physical work capacity measured as the total running distance (metres) completed during the standardized exercise protocol.

  2. Physical Performance Capacity (total work in Joules for cycling)

    Time frame: Measured during the exercise protocol immediately following administration of the study intervention.

    Total physical work capacity measured as the total mechanical work (Joules) completed during the standardized cycling exercise protocol.

  3. Physical Performance Capacity (exercise duration until exhaustion, minutes)

    Time frame: Measured during the exercise protocol immediately following administration of the study intervention.

    Total physical work capacity measured as exercise duration until volitional exhaustion during the standardized exercise protocol.

Secondary outcomes

  1. Exercise Heart Rate (bpm)

    Time frame: Continuously monitored during the exercise protocol immediately following administration of the study intervention.

    Heart rate (beats per minute) recorded continuously throughout the standardized exercise protocol.

  2. Cognitive Heart Rate (bpm)

    Time frame: Measured during cognitive testing immediately before and immediately after the exercise protocol.

    Heart rate recorded during standardized cognitive performance tasks.

  3. Post-Exercise Heart Rate Recovery (bpm)

    Time frame: Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol.

    Heart rate recorded during the post-exercise recovery period.

  4. Cognitive Reaction Time (ms)

    Time frame: Measured immediately before and immediately after the exercise protocol.

    Reaction time measured during standardized cognitive tasks (e.g., Psychomotor Vigilance Test, Stroop Test, Flanker Test).

  5. Rating of Perceived Exertion (Borg Scale, points)

    Time frame: Measured immediately after completion of the exercise protocol.

    Perceived exertion assessed using the Borg Rating of Perceived Exertion Scale (6-20).

  6. Biomechanical Kinematic Profile (cm)

    Time frame: Continuously monitored during the exercise protocol immediately following administration of the study intervention.

    Continuous recording of kinematic parameters derived from wearable sensors, including step length and vertical oscillation.

  7. Biomechanical Kinematic Profile (ms)

    Time frame: Continuously monitored during the exercise protocol immediately following administration of the study intervention.

    Continuous recording of stance time derived from wearable sensor data.

  8. Biomechanical Kinematic Profile (steps/min)

    Time frame: Continuously monitored during the exercise protocol immediately following administration of the study intervention.

    Continuous recording of cadence derived from wearable sensor data.

  9. Anthropometric Indices (kg)

    Time frame: Measured at the start of the protocol.

    Body mass expressed in kilograms.

  10. Anthropometric Indices (m)

    Time frame: Measured at the start of the protocol.

    Height expressed in metres.

  11. Body composition (fat-free mass, fat mass) (kg)

    Time frame: Measured at the start of the protocol.

    Assessment of body composition (fat-free mass, fat mass) (kg) will be performed at the start of the protocol.

  12. Body composition (fat-free mass, fat mass) (%)

    Time frame: Measured at the start of the protocol.

    Assessment of body composition (fat-free mass, fat mass) (%) will be performed at the start of the protocol.

  13. Body composition (total body water) (L)

    Time frame: Measured at the start of the protocol.

    Assessment of body composition (total body water) (L) will be performed at baseline at the start of the protocol.

  14. Body composition (total body water) (%)

    Time frame: Measured at the start of the protocol.

    Assessment of body composition (total body water) (%) will be performed at baseline at the start of the protocol.

  15. Exercise Heart Rate Variability (ms)

    Time frame: Continuously monitored during the exercise protocol immediately following administration of the study intervention.

    Heart rate variability recorded continuously throughout the standardized exercise protocol to assess autonomic regulation.

  16. Cognitive Heart Rate Variability (ms)

    Time frame: Measured during cognitive testing immediately before and immediately after the exercise protocol.

    Heart rate variability recorded during standardized cognitive performance tasks.

  17. Post-Exercise Heart Rate Variability Recovery (ms)

    Time frame: Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol.

    Heart rate variability recorded during the post-exercise recovery period.

  18. Cognitive Accuracy (%)

    Time frame: Measured immediately before and immediately after the exercise protocol.

    Accuracy measured during standardized cognitive tasks (e.g., Psychomotor Vigilance Test, Stroop Test, Flanker Test).

  19. Performance Expectancy (points)

    Time frame: Measured immediately after completion of the exercise protocol.

    Measured immediately before the exercise protocol following administration of the study intervention.

Study contacts

Contact information is provided by the study sponsor or research team.

Jakub Malik, PhD

CONTACT

[email protected]

+48739975701

Sponsors and collaborators

Lead sponsor

Poznan University of Physical Education

Other

Registry information

Official study title

Psychophysiological Mechanisms of the Placebo Effect on Physical Performance in Field Settings

Important dates

Study start
2026
Primary completion
2028
Study completion
2029
First posted
Aug 3, 2026
Registry last updated
Aug 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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