Placebo Effect in Field-Based Physical Performance

Официальное название

Psychophysiological Mechanisms of the Placebo Effect on Physical Performance in Field Settings

Обзор

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.

Подробное описание

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.

Вмешательства

• Препарат Caffeine (6mg/kg)
  Anhydrous caffeine administered in an encapsulated form at a dosage of 6mg per kilogram of body mass, 30-60 minutes before the exercise protocol.
• Другое Placebo (Starch capsule)
  Corn starch administered in an identical encapsulated form as the active caffeine, 30-60 minutes before the exercise protocol.
• Другое Sham (No Treatment)
  Participants perform the same exercise protocols without any capsule or substance administration.

Первичные конечные точки

• Physical Performance Capacity (total distance in running, metres) [Срок оценки: Measured during the exercise protocol immediately following administration of the study intervention.]
• Physical Performance Capacity (total work in Joules for cycling) [Срок оценки: Measured during the exercise protocol immediately following administration of the study intervention.]
• Physical Performance Capacity (exercise duration until exhaustion, minutes) [Срок оценки: Measured during the exercise protocol immediately following administration of the study intervention.]

Вторичные конечные точки (12)

• Exercise Heart Rate (bpm) [Срок оценки: Continuously monitored during the exercise protocol immediately following administration of the study intervention.]
• Cognitive Heart Rate (bpm) [Срок оценки: Measured during cognitive testing immediately before and immediately after the exercise protocol.]
• Post-Exercise Heart Rate Recovery (bpm) [Срок оценки: Continuously monitored during the first 5 minutes immediately following completion of the exercise protocol.]
• Cognitive Reaction Time (ms) [Срок оценки: Measured immediately before and immediately after the exercise protocol.]
• Rating of Perceived Exertion (Borg Scale, points) [Срок оценки: Measured immediately after completion of the exercise protocol.]
• Biomechanical Kinematic Profile (cm) [Срок оценки: Continuously monitored during the exercise protocol immediately following administration of the study intervention.]
• Biomechanical Kinematic Profile (ms) [Срок оценки: Continuously monitored during the exercise protocol immediately following administration of the study intervention.]
• Biomechanical Kinematic Profile (steps/min) [Срок оценки: Continuously monitored during the exercise protocol immediately following administration of the study intervention.]
• Anthropometric Indices (kg) [Срок оценки: Measured at the start of the protocol.]
• Anthropometric Indices (m) [Срок оценки: Measured at the start of the protocol.]
• Body composition (fat-free mass, fat mass) (kg) [Срок оценки: Measured at the start of the protocol.]
• Body composition (fat-free mass, fat mass) (%) [Срок оценки: Measured at the start of the protocol.]

Критерии участия

Критерии включения

• Age between 20 and 35 years,
• Healthy adults,
• Regular physical activity,
• Normal or corrected-to-normal vision,
• Habitual caffeine consumption.

Критерии исключения

• 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.

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Распределение

Рандомизированное

Модель

Параллельные группы

Маскирование

Четверное слепое

Основная цель

Фундаментальное исследование

Центры проведения

Польша · 1 центр

• Poznan University of Physical Education — Poznan

Идентификаторы

NCT: NCT07742150 · 152-1-26 · 2025/57/N/NZ4/04470

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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