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Completed

NCT Number: NCT07315776

Effects of Electrical Muscle Stimulation on Myofascial Pain Syndrome

The goal of this clinical trial is to determine if Electrical Muscle Stimulation (EMS) combined with Active Stretching (AS) (EMS+AS) and EMS+AS combined with Trigger Point Pressure Release (TPR) (EMS+AS+TPR) are effective treatments for Myofascial Pain Syndrome (MPS) in working adults. The study will also assess the safety of the EMS+AS intervention. The main questions it aims to answer are: Do EMS+AS and EMS+AS+TPR lead to greater pain reduction, increased pressure pain threshold, and improved surface electromyography (sEMG) activity when compared to standard treatments? Furthermore, what is the participant feedback regarding EMS+AS and other treatments?

Researchers will compare EMS+AS to passive stretching (PS) and TPR to see if EMS+AS and EMS+AS+TPR are effective in treating myofascial trigger points in the trapezius muscle.

Participants will receive seven interventions across a single visit, including PS, EMS+AS, TPR, TPR combined with AS (TPR+AS), EMS+AS+TPR, Sham stimulation, and Transcutaneous Electrical Nerve Stimulation (TENS). Each treatment will consist of three 10-second sets with a 10-second rest between sets, and a 2-minute break provided between different treatments. Participants will have measurements taken on changes in pain intensity, pressure pain threshold, and sEMG activity during trapezius action pre- and post-treatment. Additionally, participants will report personal information, previous MPS treatments, and baseline health status, and provide feedback on satisfaction, treatment preferences, exercise knowledge for MPS prevention, and qualitative comments. For supplementary data, we selected only the EMS+AS and TPR interventions with the same protocol to evaluate changes in range of motion and changes in trigger point size and trapezius thickness (both at rest and during stretching) via ultrasound imaging.

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Key information

Conditions

Myofascial Pain Syndrome (MPS) Muscular Diseases Musculoskeletal Diseases Myofascial Pain Syndromes Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Department of Electronic and Electrical Engineering

Bath, BA2 7AY, United Kingdom

About this study

The main study measures included changes in pain intensity, pressure pain threshold, and sEMG activity. The supplementary study measures included ultrasound images and range of motion.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participants over 18 years old with either active or latent myofascial trigger points in the trapezius muscle were diagnosed with MPS by a General Practitioner (GP).
  • Participants have no history of chronic diseases (cancer, cervical nerve root compression, heart arrhythmias, including hyperthyroid, muscle weakness, seizure, skin infection at the upper back, spinal cord injury, stroke).
  • Participants have ability to move the upper limbs.
  • Participants reported no use of pacemakers or strong pain relievers, no allergies to metals, gels, or cleaning products, and no pre-existing severe muscle soreness.

Exclusion criteria

  • Participants less 18 years old with no myofascial trigger points in the trapezius muscle.
  • Participants to have history of chronic diseases (cancer, cervical nerve root compression, heart arrhythmias, including hyperthyroid, muscle weakness, seizure, skin infection at the upper back, spinal cord injury, stroke).
  • Participants cannot move the upper limbs.
  • Participants reported use of pacemakers or strong pain relievers, and allergies to metals, gels, or cleaning products, and pre-existing severe muscle soreness.

Treatment and study plan

Therapist-assisted Passive stretching (PS)

Other

The therapist stretched the upper trapezius muscle via shoulder depression and neck deviation. The middle trapezius muscle was stretched using scapular protraction while simultaneously stabilizing the mid-spine and gently pulling the arm inward.

Other names: PS

The two-combination of EMS+AS

Other

Electrical Muscle Stimulation combined with Active Stretching: The EMS component utilized parameters of 20 Hz frequency and 100 µs pulse width, with the amplitude adjusted individually for intensity. The EMS electrodes were placed across the muscle fibers with a 1 cm inter-electrode distance. This placement was specifically designed to restrict the electrical field, thereby inducing a local muscle contraction that opposes the direction of the active stretch being performed concurrently.

Other names: EMS+AS

Trigger point pressure release (TPR)

Other

Trigger point Pressure Release (TPR): The therapist utilized a PAIN TEST™ FPX series pressure gauge (Wagner Instruments). A round rubber 1 cm2 force gauge probe was applied directly on the MTP by gradually increasing the pressure until the participant reached their maximum pressure tolerance level.

Other names: TPR

Trigger point pressure release combined with active stretching (TPR+AS)

Other

Trigger point Pressure Release combined with Active Stretching (TPR+AS) was performed by applying active stretching of the trapezius muscle concurrently with TPR, using the same protocol as the standalone TPR intervention.

Other names: TPR+AS

The triple combination therapy of EMS+AS+TPR

Other

Electrical Muscle Stimulation combined with Active Stretching during Trigger point Pressure Release (EMS+AS+TPR): This triple combination therapy utilized the EMS+AS component protocol concurrently with the TPR intervention, applying the identical protocols established for the standalone EMS+AS and TPR procedures.

Other names: EMS+AS+TPR

Transcutaneous Electrical Nerve Stimulation (TENS)

Other

Transcutaneous Electrical Nerve Stimulation (TENS) was applied using the conventional protocol (60 Hz,100 µs,5 mA) with two electrodes placed directly over the MTP region, without stretching.

Other names: TENS

Sham stimulation combined with active stretching (SS+AS)

Other

Sham stimulation combined with active stretching (SS+AS): Participants performed AS using the same EMS device and electrode placement as in the EMS+AS protocol. However, no electrical current was applied. The procedure began with a conversation about the treatment from the researcher while the current amplitude was reduced from 1 mA to 0 mA during the trapezius muscle stretching, accompanied by a beeping sound to simulate stimulation. Participants were subsequently informed that this was the intended treatment.

Other names: SS+AS

Primary outcomes

  1. Changes in Pain intensity

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in pain intensity before and after treatment were measured using a numeric rating scale (0-10), where 0 represents no pain and 10 represents the worst possible pain. A reduced score indicates a better outcome.

  2. Changes in pressure pain threshold

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in pressure pain threshold between before and after treatment were measured using a digital algometer (Wagner, Greenwich, USA). Pressure pain threshold was measured in kilogram force (kgf) or kilograms per square centimeter (kg/cm²). An increased score indicates a better outcome.

  3. Changes in median frequency of EMG activity

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in the median frequency of surface electromyography (EMG) before and after treatment were recorded in hertz (Hz) using a 16-channel sEMG (Delsys Trigno Maize Sensor system). Changes in median frequency reflect physiological changes in muscle function. An increase in median frequency during trapezius muscle activity indicates physiological improvement.

  4. % maximum volunatary contraction (MVC) improvement

    Time frame: Baseline and Day 1 (immediately post-intervention)

    %MVC improvement of EMG activity before and after treatment was recorded in percent (%) after calculating the root mean square normalized to pre-treatment values using a 16-channel sEMG (Delsys Trigno Maize Sensor system). An increase in %MVC during trapezius muscle activity indicates muscle function improvement.

Secondary outcomes

  1. Changes in range of motion (ROM) of neck deviation

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in ROM of neck deviation before and after treatment were assessed through photographic analysis. Photographs of participants are analyzed using ImageJ software, and ROM was recorded in degrees. An increase in ROM indicates improved upper trapezius muscle flexibility.

  2. Changes in myofascial trigger point (MTP) size

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in MTP size before and after treatment were assessed via ultrasound imaging and analyzed using ImageJ software. MTP size was recorded in square millimeters (mm²). A decrease in MTP size indicates improved treatment outcomes.

  3. Changes in echointensiy at the myofascial trigger point (MTP)

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in echo intensity at the MTP before and after treatment were assessed via ultrasound imaging and analyzed using ImageJ software. The echo intensity at the MTP was recorded in pixels. Changes in echo intensity reflect transient alterations in fluid accumulation or tissue structure due to fibrotic remodeling at the MTP. An increase in MTP echo intensity indicates decreased fluid accumulation, which may predict an improved treatment outcome.

  4. Changes in trapezius muscle thickness

    Time frame: Baseline and Day 1 (immediately post-intervention)

    Changes in trapezius muscle thickness at rest and during stretching were assessed via ultrasound imaging and analyzed using ImageJ software. Trapezius muscle thickness was recorded in millimetre. The observed reduction in TM thickness at rest and during stretching suggests decreased muscle tension, reflecting muscle tone improvement following treatment.

Other outcomes

  1. Particpants' feedback

    Time frame: Day 1 (Post-treatment assessment)

    Feedback questionnaires were administered to assess participant satisfaction, treatment preferences, exercise knowledge for MPS prevention, and qualitative comments. The qualitative data derived from the participants' feedback were organized into three structural domains-overall impression, lack of satisfaction, and suggestions for improvement-which emerge directly from a careful review and categorization of recurring themes within the participants' verbatim comments.

Sponsors and collaborators

Lead sponsor

University of Bath

Other

Collaborators

  • Suranaree University of Technology

Registry information

Important dates

Study start
2022
Primary completion
2024
Study completion
2025
First posted
Jan 2, 2026
Registry last updated
Jan 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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