Muscle Synergies in Pain and Pain Anticipation

Overview

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.

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

Interventions

Eligibility

Locations (2)

Outcomes

Central Contacts