Placebo Effect on Cycling Performance: Laboratory Crossover Study
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Caffeine (6mg/kg), Placebo (Starch capsule).
- Who it may be relevant to
- Registry conditions: Physical Performance, Placebo Effect, Cognitive Performance. Basic parameters: 20 years — 30 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Poland
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Official title
The Impact of Expectations on Physical Performance and Psychophysiological Potential: a Randomized, Double-blind, Placebo-controlled Crossover Study on the Placebo Effect in the Context of Caffeine Supplementation
Overview
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.
Detailed description
This study employs a randomized, double-blind, placebo-controlled crossover design to conduct a multifactorial analysis of psychophysiological and biomechanical dynamics. Participants (n = 80, aged 20-35 years) will complete four experimental sessions separated by 7-day washout periods, involving caffeine (6 mg/kg) or placebo administration. The laboratory protocol (160 minutes) integrates multiple modalities: (1) cognitive testing (Reaction Time Test and Flanker Test), (2) postural control assessment using the BTrackS Balance Plate, and (3) a standardized cycle ergometer exercise protocol consisting of 15 minutes at the anaerobic threshold followed by a 5-minute self-paced maximal effort trial. Belief manipulation (immediate vs. retrospective reporting) and cognitive anchoring (feedback conditions) are implemented to isolate expectancy-driven effects. Continuous metabolic and cardiorespiratory data collected using the Cosmed K5 system will be synchronized with blood biomarkers (lactate, glucose, caffeine, and paraxanthine) and salivary biomarkers (cortisol, testosterone, and alpha-amylase). Advanced statistical methods, including Functional Data Analysis (FDA) and machine learning, will be used to integrate physiological trajectories with behavioral predictors.
Interventions
- Drug Caffeine (6mg/kg)
Anhydrous caffeine administered in an encapsulated form at a dosage of 6 mg per kilogram of body mass, 60 minutes before the exercise protocol. - Other Placebo (Starch capsule)
Corn starch administered in an identical encapsulated form as the active caffeine, 60 minutes prior to the laboratory exercise protocol.
Primary outcome measures
- Physical Work Capacity (total work in J) [Time frame: Measured during each laboratory exercise protocol (approximately 85-120 minutes).]
Secondary outcome measures (12)
- Exercise Heart Rate (bpm) [Time frame: Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).]
- Exercise Heart Rate Variability (ms) [Time frame: Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).]
- Salivary Cortisol Concentration (nmol/L) [Time frame: 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) [Time frame: 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) [Time frame: Measured at baseline (pre-supplementation), 30 minutes post-ingestion, after warm-up (60 minutes post-ingestion), and 3 minutes post-exercise.]
- Simple Reaction Time (ms) [Time frame: Measured at T1 (pre-ingestion, minute 2 of the protocol), T2 (post-ingestion/pre-exercise, minute 55 of the protocol), and T3 (post-exercise, minute 125 of the protocol).]
- Heart Rate Recovery (bpm) [Time frame: Measured continuously during the first 5 minutes immediately following exercise cessation.]
- Postural Control (mm) [Time frame: Measured continuously during the exercise protocol and at T1 (minute 2), T2 (minute 55), and T3 (minute 125).]
- Rating of Perceived Exertion (Borg Scale, points) [Time frame: Before and immediately after warm-up, immediately after the Anaerobic Threshold phase, immediately after the Self-paced Maximal Time-trial, and immediately after cooldown during each laboratory study visit.]
- Personality Traits (NEO-FFI, points) [Time frame: Measured at baseline (first study visit).]
- Mood State (POMS/BRUMS) (points) [Time frame: Measured during each laboratory study visit.]
- Caffeine Expectancy (Caff-EQ-Brief) (points) [Time frame: Measured 30 minutes post-ingestion.]
Eligibility criteria
Inclusion criteria
- Age between 20 and 30 years,
- Healthy adults,
- Regular physical activity, but not professional athletes,
- 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.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Quadruple blind
- Primary purpose
- Basic science
Study locations
Poland · 1 center
- Poznan University of Physical Education — Poznan
Identifiers
NCT: NCT07748429 · 152-2-26 · 2025/57/N/NZ4/04470