NCT07290465

Pain Perception and Exercise-Induced Hypoalgesia Across Circadian Rhythms

Exploring Pain Perception Through Exercise-Induced Hypoalgesia Across Circadian Rhythms for Healthy Participants

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 56 (estimated)
• Sponsor: Medipol University · Academic / Other
• Sex: All
• Age: 18 Years – 40 Years
• Healthy volunteers: Accepted

Summary

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

Detailed description

Exercise-induced hypoalgesia (EIH) is a temporary reduction in pain sensitivity following physical activity. High-intensity functional training (HIFT) has been shown to produce EIH, yet the influence of circadian rhythms on this response is not well established. Circadian timing regulates physiological processes, including pain modulation, and may contribute to variability in exercise-related analgesia. This randomized crossover trial will examine whether time of day (morning vs. evening) affects EIH in healthy adults. It will also explore the relationship between an individual's chronotype, the efficacy of EIH and the difference in magnitude between men and women, the difference in effect between bony and muscular landmarks for pressure stimulus application. Null Hypothesis (H0) : Circadian rhythm has no significant influence on the efficacy of exercise-induced hypoalgesia (EIH), as measured by changes in pain perception before and after high intensity functional training at different times of day (morning vs. evening). Alternative Hypothesis (H1): Circadian rhythm significantly influences the efficacy of exercise-induced hypoalgesia (EIH), with differences in pain perception before and after high intensity functional training depending on the time of day (morning vs. evening). Each participant will complete both morning and evening sessions in randomized order, separated by ≥72 hours. Participants who completed the morning sessions will cross over to the evening sessions and vice versa. Within each session, they will perform a 12-minute supervised deep breathing control condition and a 12-minute HIFT intervention, separated by a 30-minute rest.

Conditions

• Exercise Induced Hypoalgesia
• Circadian Rhythm
• Pain Perception
• Healthy Participants
• Chronotype
• Physical Therapy

Interventions

Type	Name	Description
BEHAVIORAL	High-Intensity Functional Training (HIFT)	A 12-minute, instructor-led HIFT protocol delivered via the same video to all participants. After a 5-minute warm-up, participants perform six exercises targeting major muscle groups. The exercises are 4 lunges followed by one push-up, 10 high knees followed by 10 shuffles, burpees, squat jumps, skaters, and plank up-downs. Each exercise is done for 40 seconds then 20 seconds rest. The cycle repeats twice for a total of 12 minutes. Rate of Perceived Exertion (Borg scale) is recorded at baseline, post-warmup, during each rest interval, and immediately post-exercise. A physiotherapist supervises performance, ensures correct technique, and enforces safety and target intensity while motivating and encouraging the participant.
BEHAVIORAL	Supervised Deep Breathing	A 12-minute deep breathing session delivered via a prerecorded audio and supervised by a physiotherapist. The breathing rhythm includes inhaling for 4 seconds and exhaling for 6 seconds for a total 1 minute, followed by 1 minute of normal breathing. This cycle is repeated six times for a total duration of 12 minutes. Participants lie supine in a comfortable position and wear headphones. A self-reported Rate of Perceived Relaxation (RPR, 0-10) is recorded before and after. This serves as a non-exercise control to account for relaxation and attention effects.

Timeline

• Start date: 2026-01-01
• Primary completion: 2026-03-01
• Completion: 2026-04-01
• First posted: 2025-12-18
• Last updated: 2025-12-18

Locations

1 site across 1 country: Turkey (Türkiye)