Validation of New sEMG Electrode Placement Guidelines for the Triceps Surae in Post-stroke Individuals (Vest-P)

Background and rationale:

Surface electromyography (EMG) is a non-invasive method to measure muscle activity, among others in people after a stroke during gait analysis. Measurement quality is strongly influenced by electrode placement. However, the commonly used SENIAM guidelines do not take individual variations in muscle morphology into account, which can lead to inaccurate measurements. In previous research demonstrated that the standard placement on the triceps surae (medial and lateral gastrocnemius and soleus) was suboptimal at the group level and sometimes even problematic at the individual level. Therefore, new placement guidelines (EPICA guidelines, Electrode Placement for Individual Calf Anatomy) were developed, which are currently being tested in healthy individuals.

Method:

In this project aims to validate these newly developed guidelines in people after a stroke who exhibit atrophy of their calf muscles. For each participant, electrode positions on the hemiplegic side will be determined according to our guidelines while the participant is lying prone. Circular stickers will be used instead of actual EMG electrodes and will be placed according to the EPICA guidelines as well as according to the SENIAM guidelines. Subsequently, the muscle borders of the triceps surae will be identified on the participant's leg using 2D ultrasound. Afterwards, the distance between the electrodes and the surrounding muscle borders will be measured to map electrode placement on the muscle in order to validate the guidelines.

In the second part of this study, 3D ultrasound recordings will be made of the soleus, medial gastrocnemius, and lateral gastrocnemius with the electrodes (stickers) on these muscles, so that during image processing, electrode positions can be visualized relative to the entire muscle, including along the depth axis. In addition, participants who can safely walk without an ankle-foot orthosis will be asked to walk a maximum of five times ten meters. Additionally, an ultrasound probe will be attached to the leg to investigate how the electrode position relates to the muscle-tendon junction during movement. Subsequently, actual electrodes will also be placed to record muscle activity during walking and heel raises.

Furthermore, all participants will be asked to do a heel raise to activate the calf muscles. As such, the quality of the EMG signals will be evaluated. Other measurements will included: Fugl-Meyer Assessment of the lower limb, measure passive ankle range of motion with a goniometer, and measure lower leg length with a tape measure. These will be used as descriptive parameters of our study population.

Patients will be asked on a voluntary basis to participate in a second, short measurement approximately two weeks after the first session. During this measurement, electrode placement will again be performed according to the EPICA guidelines. 3D ultrasound will again be used to calculate the distances between the electrodes and the muscle borders. This second measurement is necessary to investigate the test-retest reliability of the EPICA guidelines in people after a stroke.

Study Overview

• Status: Recruiting
• Conditions: Stroke

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

Study Locations

• Belgium
  • Oost-Vlaanderen
    • Ghent, Oost-Vlaanderen, Belgium, 9000
      • Recruiting
      • Ghent University Hospital
      • Contact: Hiruz; Phone Number: +32 9 332 05 30; Email: hiruz@uzgent.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Persons after stroke.

Description

Inclusion Criteria:

• Adult individuals who have experienced a stroke (CVA or cerebrovascular accident).
• Have no other neurological disorder.
• Are able to lie in the prone position for approximately one and a half hours.
• Are able to walk without shoes for the walking component (only applicable to participants who will perform walking). The use of an assistive device such as a walking stick (or similar) is permitted.

Exclusion Criteria:

• Presence of other neurological or orthopedic conditions that may influence the measurements and results (e.g., Parkinson's disease, peripheral neuropathy of the lower limbs, severe ankle osteoarthritis limiting range of motion, etc.).
• Having undergone a surgical intervention on the hemiparetic lower leg (e.g., ankle joint arthrodesis, etc.).
• Severe cognitive impairments that prevent understanding participation in the study (assessed using the AbilityQ).

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Persons after stroke.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Electrode-muscle boundary distances for EPICA-electrodes	These distances, measured with a tape measure, will be obtained between the EPICA electrode positions and the muscle boundaries as visualized using 2D ultrasound.	At study enrollment and a second time at least two weeks later.
Electrode-muscle boundary distances for SENIAM-electrodes	These distances, measured with a tape measure, will be obtained between the SENIAM electrode positions and the muscle boundaries as visualized using 2D ultrasound.	At study enrollment.
Triceps surae muscle geometry	Triceps surae muscle geometry will be measured using 3D freehand ultrasound.	At study enrollment.
Muscle-tendon junction displacement of the lateral gastrocnemius during walking.	This will be measured with dynamic 2D ultrasound.	At study enrollment.
Muscle-tendon junction displacement of the lateral gastrocnemius during a heel raise.	This will be measured using dynamic 2D ultrasound.	At study enrollment.
Muscle-tendon junction displacement of the medial gastrocnemius during walking.	This will be measured using dynamic 2D ultrasound.	At study enrollment.
Muscle-tendon junction displacement of the medial gastrocnemius during a heel raise.	This will be measured using dynamic 2D ultrasound.	At study enrollment.
Quality features of the surface electromyography signals obtained from the EPICA electrodes during the dynamic tasks.		At study enrollment.
Quality features of the surface electromyography signals obtained from the SENIAM electrodes during the dynamic tasks.		At study enrollment.
Passive ankle range of motion.	This will be measured using a manual goniometer.	At study enrollment.
Fugl-Meyer Assessment score of the paretic lower limb.	Minumum score is 0 and maximum score is 34. A higher score involves a less impaired hemiparetic leg.	At study enrollment.
Surface electromyography amplitude during the dynamic tasks.		At study enrollment.
Surface electromyography timing during the dynamic tasks.		At study enrollment.
Spatiotemporal parameters derived from inertial measurement units		At study enrollment.

Collaborators and Investigators

• Sponsor: University Hospital, Ghent
• Collaborators: University Ghent; Vrije Universiteit Brussel; Research Foundation Flanders

Publications and helpful links

General Publications

• De Vlieger D, Bosman L, Swinnen E, Besomi M, Aeles J. Assessment of common electrode placement methods for surface electromyography recordings of the triceps surae muscles. J Electromyogr Kinesiol. 2025 Dec;85:103080. doi: 10.1016/j.jelekin.2025.103080. Epub 2025 Oct 24.

Study record dates

Study Major Dates

• Study Start (Actual): April 17, 2026
• Primary Completion (Estimated): October 31, 2027
• Study Completion (Estimated): October 31, 2027

Study Registration Dates

• First Submitted: January 27, 2026
• First Submitted That Met QC Criteria: January 27, 2026
• First Posted (Actual): February 4, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: June 1, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: guidelines; Surface electromyography; 3D freehand ultrasound; SENIAM
• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Stroke
• Other Study ID Numbers: ONZ-2025-0433; 11PKX24N (Other Grant/Funding Number: Research foundation Flanders)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No