Clinical trial NCT06929559: Muscular Synergies and Behavioral Adaptations of Gait in Pain Anticipation (SYAMAPP)
Official title: Muscular Synergies and Behavioral Adaptations of Gait in Pain Anticipation (SYAMAPP)
Study type: INTERVENTIONAL
Overall status: NOT_YET_RECRUITING
Phase: NA
Conditions: Nocebo Effect
Pain Anticipation
Keywords: Nocebo effect
Pain anticipation
Pain expectation
Motricity
Gait
Walking
Healthy
Muscle synergies
Lead sponsor: Universite de Picardie Jules Verne
Sponsor class: OTHER
First posted: 2025-04-16
Enrollment: 34
Sex: ALL
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: The purpose of this study is to determine whether the anticipation of pain influences gait control and psychophysiological responses in healthy individuals. Participants will receive a neutral cream described either as potentially painful (experimental group) or inert (control group), and their behavioral and physiological adaptations will be measured during walking tasks.

Detailed description: Pain anticipation can significantly alter motor behavior and physiological responses, even in the absence of actual pain. While previous research has established that conditioned expectations can modify gait patterns, muscle activation, and autonomic responses, the specific locomotor adaptations triggered by pain anticipation in healthy individuals remain insufficiently understood. This study examines how manipulating expectations about a neutral cream influences gait control and psychophysiological markers during walking tasks.

Participants will be recruited through university announcements including posters and emails, with eligibility determined via an online screening questionnaire and verbal confirmation the day of the experience. Healthy adults aged 18-35 who meet the inclusion criteria will participate in a single 90-minute experimental session. Random assignment will place participants into either an experimental group, where they receive the neutral cream with verbal suggestions that it may cause localized pain, or a control group that receives identical application with neutral instructions.

The experimental protocol consists of two primary walking assessments conducted both before and after cream application. First, participants perform free walking trials on a GAITRite mat to measure baseline spatiotemporal parameters including walking speed, cadence, and step length at a comfortable speed until completion of 30 gait cycles. Second, treadmill walking and running trials using a Zebris system evaluate gait transitions through incremental speed changes from 0.5 m/s to 4.1 m/s in increments of 0.4 m/s with 10 second familiarisation time in-between measurements. Both walking tasks are recorded using GoPro cameras to subsequent analysis of changes in joint amplitudes. Throughout these tasks, physiological monitoring captures muscle activity via surface EMG, cardiac responses through ECG and heart rate variability measurements, and electrodermal activity as an indicator of autonomic arousal.

Following the first movement assessments and before the application of the cream, participants complete standardized questionnaires evaluating pain perception using the Brief Pain Inventory and visual analog scales (VAS), fear of movement through the Tampa Scale of Kinesiophobia and Fear-Avoidance Components Scale, and pain catastrophizing via the Pain Catastrophizing Scale.

The cream is applied at the level of the knee, between the two lateral epicondyles of the femur with a 4 cm width, and another VAS is filled in after application. The walking tasks are repeated, measuring the same physiological signs and three more VAS's are administered: one during the treadmill walking task, at the end of the 1.3 m/s speed recording, another during the free walking task, after half of the completed gait cycles, and a final one at the end of the protocol.

The primary outcome measure focuses on changes in the walk ratio, calculated as step length divided by cadence, while secondary outcomes examine alterations in kinematic patterns, muscle activation strategies, and autonomic nervous system responses.

Eligibility criteria: Inclusion Criteria:

* Aged 18-35 years
* 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 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

Primary outcomes:
measure: Walk ratio
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
Secondary outcomes:
measure: Muscle synergies
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
measure: Gait Kinematics: Joint amplitudes
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
measure: ECG/Heart Rate Variability (HRV)
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
measure: Electrodermal Activity (EDA)
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
measure: Pain Catastrophizing (PCS)
timeFrame: Before intervention.
measure: Fear-Avoidance Beliefs (FACS)
timeFrame: Before intervention.
measure: Kinesiophobia (TSK)
timeFrame: Before intervention.
measure: Pain Severity (BPI)
timeFrame: Before intervention.
measure: Self-Reported Pain (VAS)
timeFrame: 1 and 2. before and after application of the cream (intervention); 3. During the treadmill task: upon finishing the 1.3 m/s speed recording; 4. During the free-walking task: at half of the gait cycles; 5. Upon finishing all tasks.
measure: Gait Variability Index
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
measure: Gait Symmetry Index
timeFrame: During intervention (pre/post cream application): for the mat, during a 2-minute free walk and for the treadmill, during a 5-minute treadmill walk with increases in speed every 30 seconds.
Other outcomes:
Locations:
city: Amiens
country: France
facility: Université de Picardie Jules Verne
Study officials:
affiliation: Lecturer
name: Thierry Lelard, PhD
role: STUDY_DIRECTOR
affiliation: Lecturer
name: Maryne Cozette, PhD
role: STUDY_DIRECTOR
References:
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citation: Nishi Y, Osumi M, Sumitani M, Yozu A, Morioka S. Kinematic changes in goal-directed movements in a fear-conditioning paradigm. Sci Rep. 2021 May 27;11(1):11162. doi: 10.1038/s41598-021-90518-7.
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citation: Horvath A, Koteles F, Szabo A. Nocebo effects on motor performance: A systematic literature review. Scand J Psychol. 2021 Oct;62(5):665-674. doi: 10.1111/sjop.12753. Epub 2021 Jun 18.