Nocebo Effect, Pain, Pain Anticipation
Conditions
Keywords
Nocebo effect, Pain anticipation, Pain, Gait, Motricity, Muscle synergies
Brief summary
This study investigates how the anticipation of pain affects muscle synergies. One group will be recruited who will first experience actual pain from capsaicin cream and are then presented with a harmless cream deceptively labeled as capsaicin. 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 experimental Group ("Prior Experience"): Individuals who report a prior painful experience with capsaicin cream. Participants will complete a first session consisting on 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). Then, a capsaicin 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 participants will come to the laboratory a second time to measure the same outcomes but, instead of applying capsaicin again, they will receive an inert cream presented as capsaicin (neutral massage cream MEDICAFARM). The procedure will be repeated. 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.
Interventions
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.
OTHERGait 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.
Sponsors
Universite de Picardie Jules Verne
Mitacs
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Masking description
Participants are not aware that a cream applied to them (neutral cream) does not produce any pain.
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Aged 18-35 years old * Healthy participant with no self-reported diagnosed neurological, musculoskeletal, or cardiovascular disorders * Body Mass Index (BMI) \< 30 * Ability to walk unaided for at least 10 minutes without major physical limitations
Exclusion criteria
* Presence of pain at the time of testing * Self-reported diagnosed condition affecting mobility * Known allergy to any component of the study cream * Allergy to EMG electrode adhesives * Inability to stand unassisted for more than 1 minute * Inability to walk/run at the required speed and distance * Weight exceeding 150 kg (due to treadmill limitations) * Recent intake (prior intervention) of: * Analgesics (within 6 hours) * Cigarettes (within 6 hours) * Caffeine (within 2 hours) * Skin lesions at the cream application site * Pregnancy * Failure to understand instructions * Daytime pain reported by participant on day of experimentation
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Distribution of muscle synergies derived by non-negative matrix factorization | Before intervention, after intervention (10 minutes after cream application) | Changes in the activation of the muscle synergies during the gait cycle. |
| Changes in Muscle Synergy Composition derived by non-negative matrix factorization. | Before intervention, after intervention (10 minutes after cream application) | Changes in the composition of muscle synergies (i.e., the individuals muscles that comform one muscle synergy) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Tampa Scale for Kinesiophobia (TSK) | Before intervention. | Tampa Scale of Kinesiophobia total score (17-68). Users rate 17 statements in a scale from 1 (Strongly disagree) to 4 (Strongly agree). |
Countries
Canada, France
Contacts
CONTACTJennifer Burgos-Tirado, M.Sc.A., Ing.
STUDY_DIRECTORThierry Lelard, PhD, HDR
Lecturer
STUDY_DIRECTORMaryne Cozette, PhD, Lecturer
Lecturer
STUDY_DIRECTORGuillaume Léonard, PhD, Lecturer
Lecturer
Outcome results
None listed