Pain Perception and Exercise-Induced Hypoalgesia Across Circadian Rhythms

The goal of this randomized crossover clinical trial is to investigate whether exercise-induced hypoalgesia (EIH) is influenced by circadian rhythm in healthy adults aged 18-40 years. The main questions it aims to answer are: * Does the time of day (morning vs. evening) influence changes in pain perception following exercise? * Do chronotype, sex, or stimulation site (bony vs. muscular) alter the magnitude of this effect? Participants will: * Complete questionnaires * Undergo quantitative sensory testing * Attend both morning and evening sessions in randomized crossover order