Cognitive Performance, Physical Performance, Placebo Effect
Conditions
Keywords
Caffeine, Expectancy, Psychophysiology, Exercise Physiology, Postural Control, Human Performance
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.
Interventions
Anhydrous caffeine administered in an encapsulated form at a dosage of 6mg per kilogram of body mass, 30-60 minutes before the exercise protocol.
Corn starch administered in an identical encapsulated form as the active caffeine, 30-60 minutes before the exercise protocol.
OTHERSham (No Treatment)
Participants perform the same exercise protocols without any capsule or substance administration.
Sponsors
Poznan University of Physical Education
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Intervention model description
Participants are randomly assigned to one of three parallel groups: Caffeine, Placebo, or Control, with a single testing visit per participant.
Eligibility
Sex/Gender
ALL
Age
20 Years to 35 Years
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Physical Performance Capacity (total distance in running, metres) | 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) | 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) | 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
| Measure | Time frame | Description |
|---|---|---|
| Exercise Heart Rate (bpm) | 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. |
| Cognitive Heart Rate (bpm) | Measured during cognitive testing immediately before and immediately after the exercise protocol. | Heart rate recorded during standardized cognitive performance tasks. |
| Post-Exercise Heart Rate Recovery (bpm) | Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol. | Heart rate recorded during the post-exercise recovery period. |
| Cognitive Reaction Time (ms) | 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). |
| Rating of Perceived Exertion (Borg Scale, points) | Measured immediately after completion of the exercise protocol. | Perceived exertion assessed using the Borg Rating of Perceived Exertion Scale (6-20). |
| Biomechanical Kinematic Profile (cm) | 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. |
| Biomechanical Kinematic Profile (ms) | Continuously monitored during the exercise protocol immediately following administration of the study intervention. | Continuous recording of stance time derived from wearable sensor data. |
| Biomechanical Kinematic Profile (steps/min) | Continuously monitored during the exercise protocol immediately following administration of the study intervention. | Continuous recording of cadence derived from wearable sensor data. |
| Anthropometric Indices (kg) | Measured at the start of the protocol. | Body mass expressed in kilograms. |
| Anthropometric Indices (m) | Measured at the start of the protocol. | Height expressed in metres. |
| Body composition (fat-free mass, fat mass) (kg) | 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. |
| Body composition (fat-free mass, fat mass) (%) | 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. |
| Body composition (total body water) (L) | 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. |
| Body composition (total body water) (%) | 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. |
| Exercise Heart Rate Variability (ms) | 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. |
| Cognitive Heart Rate Variability (ms) | Measured during cognitive testing immediately before and immediately after the exercise protocol. | Heart rate variability recorded during standardized cognitive performance tasks. |
| Post-Exercise Heart Rate Variability Recovery (ms) | Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol. | Heart rate variability recorded during the post-exercise recovery period. |
| Cognitive Accuracy (%) | Measured immediately before and immediately after the exercise protocol. | Accuracy measured during standardized cognitive tasks (e.g., Psychomotor Vigilance Test, Stroop Test, Flanker Test). |
| Performance Expectancy (points) | Measured immediately after completion of the exercise protocol. | Measured immediately before the exercise protocol following administration of the study intervention. |
Countries
Poland
Contacts
CONTACTJakub Malik, PhD
PRINCIPAL_INVESTIGATORJakub Malik, PhD
Poznan University of Physical Education, Department of Sports Psychology
Outcome results
None listed