NCT07251387

Muscle Synergies in Pain and Pain Anticipation

Test-retest Fidelity of a Tool for Calculation of Muscle Synergies

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 34 (estimated)
• Sponsor: Universite de Picardie Jules Verne · Academic / Other
• Sex: All
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

This study investigates how the anticipation of pain affects muscle synergies. Two groups will be compared: an experimental group, who first experience actual pain from capsaicin cream and are then presented with a harmless cream deceptively labeled as capsaicin, against a control group, who are presented with a harmless cream labeled as potentially painful, without any prior painful experience. The changes in muscle synergies will be measured during walking tasks.

Detailed description

Participants will be recruited through university announcements. Eligibility will be determined by a screening process that assesses prior experience with capsaicin cream. Healthy adults aged 18-35 who meet the inclusion criteria will be enrolled and assigned to one of two groups based on their screening responses: 1. Experimental Group ("Prior Experience"): Individuals who report a prior painful experience with capsaicin cream. 2. Control Group ("No Prior Experience"): Individuals who report no prior experience with capsaicin cream. All participants will take part in a single experimental session. Both groups will receive identical negative verbal suggestions indicating that a neutral, harmless cream is a potent capsaicin formulation likely to cause pain. Participants will complete a walking assessment on a treadmill. The speed will be incrementally increased from 0.8 m/s to 1.1 m/s. Throughout this task, muscle activity will be recorded via electromyography (EMG), and ground reaction forces will be captured by force platforms embedded in the treadmill. Following the initial walk, participants will complete a set of standardized questionnaires to establish baseline scores for pain perception (Visual Analog Scale, VAS), fear of movement (Tampa Scale of Kinesiophobia, TSK), and pain catastrophizing (Pain Catastrophizing Scale, PCS). The neutral cream will be applied to the knee, specifically in the area between the lateral epicondyles of the femur, in a 4 cm wide band. Participants will immediately fill out the VAS to report any pain sensations. The walking assessment is repeated, measuring the same physiological signals (EMG and ground reaction forces). The primary objective is to determine whether a prior painful experience with capsaicin causes individuals to generalize that pain memory to a neutral sensation, leading to different outcomes than in those who only have a negative expectation. We will specifically investigate the magnitude of this effect on muscle synergies and ground reaction forces.

Conditions

• Pain
• Nocebo Effect
• Pain Anticipation

Interventions

Type	Name	Description
OTHER	Pain expectation conditioning	Participants receive a neutral cream with no real harmful effects with verbal and behavioral suggestions that it may cause localized pain. Researchers wear gloves during application and emphasize the potential discomfort, stating effects may intensify with movement.
OTHER	Gait assesment	Gait will be assessed both before and after cream application. Each assessment will consist of walking on a treadmill at varying speeds while physiological data (EMG) is recorded. Identical questionnaires (VAS, TAMPA, and PCS) will be administered immediately following the first gait assessment.

Timeline

• Start date: 2026-01-01
• Primary completion: 2026-02-01
• Completion: 2026-04-01
• First posted: 2025-11-26
• Last updated: 2025-11-26

Locations

2 sites across 2 countries: Canada, France