Placebo Effect on Cycling Performance: Laboratory Crossover Study

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.

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.