Placebo Effect on Cycling Performance: Laboratory Crossover Study

NCT07748429 | Not Yet Recruiting

• 2 other identifiers: 152-2-262025/57/N/NZ4/04470
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to determine the impact of the placebo (PLA) effect on physical and cognitive performance in a controlled laboratory setting. The study investigates how expectations and beliefs about substance intake (caffeine vs. placebo) interact with actual consumption to influence performance and physiological stress markers. Healthy adults (n = 80) will participate in four testing sessions using a randomized, double-blind, placebo-controlled crossover design. Physiological stress markers (cortisol and alpha-amylase), heart rate, and performance metrics will be monitored during a standardized cycling exercise protocol. This phase provides the dense mechanistic data required to refine a mathematical model of the placebo effect, offering insights into how individual personality traits and cognitive anchoring influence psychophysiological potential.

Conditions

Physical Performance; Cognitive Performance; Placebo Effect

Keywords

Caffeine; Expectancy; Psychophysiology; Exercise PHysiology; Postural Control; Human Performance

Outcome Measures

Primary Outcomes (1)

• Physical Work Capacity (total work in J)

  Total physical work performed, expressed in Joules (J), during the standardized laboratory exercise protocol, including both the Anaerobic Threshold phase and the Self-paced Maximal Time-trial.

  Measured during each laboratory exercise protocol (approximately 85-120 minutes).

Secondary Outcomes (54)

• Exercise Heart Rate (bpm)

  Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).

• Exercise Heart Rate Variability (ms)

  Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).

• Salivary Cortisol Concentration (nmol/L)

  Measured at baseline (pre-supplementation), 30 minutes post-ingestion, after warm-up (60 minutes post-ingestion), and 3 minutes post-exercise.

• Salivary Testosterone Concentration (pmol/L)

  Measured at baseline (pre-supplementation), 30 minutes post-ingestion, after warm-up (60 minutes post-ingestion), and 3 minutes post-exercise.

• Salivary Alpha-amylase Activity (U/L)

  Measured at baseline (pre-supplementation), 30 minutes post-ingestion, after warm-up (60 minutes post-ingestion), and 3 minutes post-exercise.

Study Arms (4)

Sequence AABB

EXPERIMENTAL

Participants follow the sequence: Caffeine, Caffeine, Placebo, Placebo, with a 7-day washout period between sessions.

Drug: Caffeine (6mg/kg); Other: Placebo (Starch capsule)

Sequence BBAA

EXPERIMENTAL

Participants follow the sequence: Placebo, Placebo, Caffeine, Caffeine, with a 7-day washout period between sessions.

Drug: Caffeine (6mg/kg); Other: Placebo (Starch capsule)

Sequence ABAB

EXPERIMENTAL

Participants follow the sequence: Caffeine, Placebo, Caffeine, Placebo, with a 7-day washout period between sessions.

Drug: Caffeine (6mg/kg); Other: Placebo (Starch capsule)

Sequence BABA

EXPERIMENTAL

Participants follow the sequence: Placebo, Caffeine, Placebo, Caffeine, with a 7-day washout period between sessions.

Drug: Caffeine (6mg/kg); Other: Placebo (Starch capsule)

Interventions

Caffeine (6mg/kg) DRUG

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

Sequence AABB; Sequence ABAB; Sequence BABA; Sequence BBAA

Placebo (Starch capsule) OTHER

Corn starch administered in an identical encapsulated form as the active caffeine, 60 minutes prior to the laboratory exercise protocol.

Sequence AABB; Sequence ABAB; Sequence BABA; Sequence BBAA

Eligibility Criteria

• Age: 20 Years - 30 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age between 20 and 30 years,
• Healthy adults,
• Regular physical activity, but not professional athletes,
• Normal or corrected-to-normal vision,
• Habitual caffeine consumption.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Poznan University of Physical Education: lead

Study Sites (1)

Poznan University of Physical Education

Poznan, Wielkopolska, Poland

Location

MeSH Terms

Interventions

Caffeine; Starch

Intervention Hierarchy (Ancestors)

Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Glucans; Biopolymers; Polymers; Macromolecular Substances; Dietary Carbohydrates; Carbohydrates; Polysaccharides

Study Officials

• Jakub Malik, PhD

  Poznan University of Physical Education, Department of Sports Psychology

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Jakub Malik, PhD

CONTACT

+48739975701; malik@awf.poznan.pl

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants are divided into two MetaGroups (MG1 and MG2). MG1 follows a fully blinded crossover design (sequences AABB or BBAA), while MG2 follows a partially blinded mixed design (sequences ABAB or BABA), with all participants undergoing four experimental sessions separated by a 7-day washout period.

Study Record Dates

• First Submitted: July 21, 2026
• First Posted: August 5, 2026
• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): March 31, 2028
• Study Completion (Estimated): March 31, 2029
• Last Updated: August 5, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL
• Time Frame: The study protocol will be available upon its publication. The IPD and analytic code will be available starting from the date of the primary study results publication and will remain accessible for at least 5 years.
• Access Criteria: The study protocol will be published as an open-access article. Upon completion of the study, de-identified individual participant data (IPD) and relevant analytic code will be deposited in an open-access repository such as Zenodo or OSF, in accordance with FAIR principles.

Locations

PL (1)