Pain Perception and Exercise-Induced Hypoalgesia Across Circadian Rhythms

Inclusion Criteria: * Healthy participants * age 18 to 40 years * good level of English that allow the enrolled participant to provide informed consent and complete the questionnaires provided * being categorized as "moderate" in the International Physical Activity Questionnaire (IPAQ) Exclusion Criteria: * inability to report pain intensity reliably * consumption of narcotics or tobacco products * regularly taking pain medications and analgesics * pregnant or planning to get pregnant * surgery within the last 12 months * acute or chronic pain conditions * uncontrolled hypertension * cardiovascular diseases, pulmonary diseases, neurological diseases with significant changes in somatosensory and pain perception, metabolic diseases, serious systemic diseases or conditions that restrict normal daily activities, inflammatory conditions (e.g. rheumatoid arthritis), or orthopedic injuries * intolerable pain during the pain perception test * serious psychiatric conditions (e.g., schizophrenia and bipolar disorder) or psychological disorders (e.g., depression) that may affect pain thresholds (16). * Severe sleep disorders and circadian rhythm disturbances * BMI \> 30 * serious fatigue or delayed-onset muscle soreness (9) at least 24 h after exercise sessions or a sudden change in activity for more than one week