Placebo Effect on Cycling Performance: Laboratory Crossover Study
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age20-35
SponsorPoznan University of Physical Education
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Age between 20 and 35 years,
Healthy adults,
Regular physical activity, but not professional athletes,
Normal or corrected-to-normal vision,
Disqualifiers
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,
Trial design
Design model
Crossover
Treatments tested in this trial
Caffeine (6mg/kg)
DrugAnhydrous caffeine administered in an encapsulated form at a dosage of 6 mg per kilogram of body mass, 60 minutes before the exercise protocol.
Placebo (Starch capsule)
Other interventionCorn starch administered in an identical encapsulated form as the active caffeine, 60 minutes prior to the laboratory exercise protocol.
Treatment groups
80 Participants
are divided into 4 treatment groupsGroup A: Sequence AABBExperimental treatment 2 interventions
Group B: Sequence BBAAExperimental treatment 2 interventions
Group C: Sequence ABABExperimental treatment 2 interventions
Group D: Sequence BABAExperimental treatment 2 interventions
Trial outcomes
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.
Time frame
Measured during each laboratory exercise protocol (approximately 85-120 minutes).2
Psychomotor Vigilance Test Reaction Time (ms)
Reaction time during the Psychomotor Vigilance Test expressed in milliseconds (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).3
Flanker Test Reaction Time (ms)
Reaction time during the Flanker Test expressed in milliseconds (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).4
Postural Control (mm)
Center of Pressure excursions measured using the BTrackS Balance Plate and expressed in millimeters (mm).
Time frame
Measured continuously during the exercise protocol and at T1 (minute 2), T2 (minute 55), and T3 (minute 125).Secondary outcomes
1
Exercise Heart Rate (bpm)
Heart rate expressed in beats per minute (bpm) recorded continuously throughout the standardized laboratory exercise protocol.
Time frame
Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).2
Exercise Heart Rate Variability (ms)
Heart rate variability expressed in milliseconds (ms) and recorded continuously throughout the standardized laboratory exercise protocol to assess autonomic regulation.
Time frame
Measured continuously during each laboratory exercise protocol (approximately 85-120 minutes).3
Salivary Cortisol Concentration (nmol/L)
Salivary cortisol concentration expressed in nmol/L.
Time frame
Measured at baseline (pre-supplementation), 30 minutes post-ingestion, before warm-up (60 minutes post-ingestion), 3 minutes post-exercise, and 10 minutes post-exercise.4
Salivary Testosterone Concentration (pmol/L)
Salivary testosterone concentration expressed in pmol/L.
Time frame
Measured at baseline (pre-supplementation), 30 minutes post-ingestion, before warm-up (60 minutes post-ingestion), 3 minutes post-exercise, and 10 minutes post-exercise.Sponsors and contacts
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Source ClinicalTrials.gov
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