Psychophysiological Mechanisms of the Placebo Effect on Physical Performance in Field Settings
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Enrollment
- 120
- Locations
- 1
- Primary Endpoint
- Physical Performance Capacity (total distance in running, metres)
Study Overview
Brief Summary
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.
Detailed Description
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Basic Science
- Masking
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Eligibility Criteria
- Ages
- 20 Years to 35 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
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.
Outcomes
Primary Outcomes
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.
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.
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
- Exercise Heart Rate (bpm)(Continuously monitored during the exercise protocol immediately following administration of the study intervention.)
- Cognitive Heart Rate (bpm)(Measured during cognitive testing immediately before and immediately after the exercise protocol.)
- Post-Exercise Heart Rate Recovery (bpm)(Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol.)
- Cognitive Reaction Time (ms)(Measured immediately before and immediately after the exercise protocol.)
- Rating of Perceived Exertion (Borg Scale, points)(Measured immediately after completion of the exercise protocol.)
- Biomechanical Kinematic Profile (cm)(Continuously monitored during the exercise protocol immediately following administration of the study intervention.)
- Biomechanical Kinematic Profile (ms)(Continuously monitored during the exercise protocol immediately following administration of the study intervention.)
- Biomechanical Kinematic Profile (steps/min)(Continuously monitored during the exercise protocol immediately following administration of the study intervention.)
- Anthropometric Indices (kg)(Measured at the start of the protocol.)
- Anthropometric Indices (m)(Measured at the start of the protocol.)
- Body composition (fat-free mass, fat mass) (kg)(Measured at the start of the protocol.)
- Body composition (fat-free mass, fat mass) (%)(Measured at the start of the protocol.)
- Body composition (total body water) (L)(Measured at the start of the protocol.)
- Body composition (total body water) (%)(Measured at the start of the protocol.)
- Exercise Heart Rate Variability (ms)(Continuously monitored during the exercise protocol immediately following administration of the study intervention.)
- Cognitive Heart Rate Variability (ms)(Measured during cognitive testing immediately before and immediately after the exercise protocol.)
- Post-Exercise Heart Rate Variability Recovery (ms)(Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol.)
- Cognitive Accuracy (%)(Measured immediately before and immediately after the exercise protocol.)
- Performance Expectancy (points)(Measured immediately after completion of the exercise protocol.)