Impact of Different Electrical Frequencies Used in Percutaneous Neuromodulation on Muscle Strength and Pressure Pain Thresholds (PENS-DOSE)

May 5, 2026 updated by: JUAN ANTONIO VALERA CALERO, Universidad Complutense de Madrid

Percutaneous electrical nerve stimulation (PENS) involves delivering electrical currents through fine filiform needles inserted near tissues such as muscles, ligaments, or nerves. It has been explored for various chronic pain conditions affecting the cervical and lumbar spine, as well as the upper and lower limbs. Despite its growing clinical use, the overall quality of evidence supporting PENS for chronic musculoskeletal pain remains limited. Most studies have applied the technique directly over nerve structures, and while some reviews have shown greater pain reduction compared to transcutaneous electrical nerve stimulation (TENS), the superiority of PENS has not been conclusively demonstrated. Research specifically examining its application on nerve tissues, particularly in the upper limbs, remains scarce. Some preliminary and single-case studies have reported improvements in pain and disability following PENS directed at the radial nerve, but these findings are limited by small sample sizes and the absence of control groups. The physiological mechanisms underlying PENS are still not fully understood, though both peripheral and central processes are believed to be involved. Evidence suggests that PENS can reduce local sensitivity to pressure pain through peripheral mechanisms and may also enhance descending inhibitory control by activating conditioned pain modulation at the central level. However, further studies are necessary to clarify these effects.

Since to date, limited research has specifically examined the optimal PENS dosage, the present study aimed to compare two PENS dosage for improving muscle strength and pain pressure thresholds.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Juan Antonio Valera-Calero, PhD
  • Phone Number: 0034 653 766 841
  • Email: juavaler@ucm.es

Study Locations

  • Poland
      • Nowy Targ, Poland, 34-400
    • Poland
      • Krakow, Poland, Poland
        • Not yet recruiting
        • ATMIS
        • Contact:
          • Juan Antonio Valera-Calero
          • Phone Number: 0034 653 766 841
          • Email: juavaler@ucm.es

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Presence of at least one latent myofascial trigger point (MTrP) in the infraspinatus muscle, identified according to the most recent Delphi consensus criteria.
  • Ability to read, understand, and sign the written informed consent form.

Exclusion Criteria:

  • Current pharmacological treatment that may affect muscle tone.
  • History of shoulder or spinal surgery.
  • Traumatic disorders such as whiplash-associated injuries, dislocations, or fractures.
  • Neuropathies, including radiculopathies or myelopathies.
  • Severe medical conditions (e.g., tumors, fractures, neurological or systemic diseases).
  • Clinically relevant asymmetries.
  • Generalized musculoskeletal conditions such as fibromyalgia.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Low Frequency PENS
Participants will receive a single session of PENS setting 2 Hz frequency, 250 µs pulse width, 10 minutes duration, with an intensity (mA) sufficient to elicit a visible motor response while remaining comfortable for the patient.
Other: Percutaneous electrical nerve stimulation: Low frequency
A single PENS session will be applied under ultrasound guidance using sterile, single-use filiform needles placed in the suprascapular and axillary nerves and connected to an electrostimulator APSe4 (Agupunt, Barcelona). Dosage will be: 2 Hz frequency, 250 µs pulse width, 10 minutes duration, with an intensity (mA) sufficient to elicit a visible motor response while remaining comfortable for the patient.
Experimental: High Frequency PENS
Participants will receive a single session of PENS setting 100 Hz frequency, 250 µs pulse width, 5-second stimulation followed by 55-second rest, with an intensity (mA) sufficient to elicit a visible motor response while remaining comfortable for the patient and repeated five times.
Other: Percutaneous electrical nerve stimulation: High frequency

A single PENS session will be applied under ultrasound guidance using sterile, single-use filiform needles placed in the suprascapular and axillary nerves and connected to an electrostimulator APSe4 (Agupunt, Barcelona).

Dosage will be: 100 Hz frequency, 250 µs pulse width, 5-second stimulation followed by 55-second rest, repeated five times

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Muscle strength
Time Frame: Baseline
Shoulder external rotator strength will be assessed using a handheld dynamometer (TruStrength, Hawkin Dynamics, USA), previously validated for measuring isometric muscle contraction strength. Participants will perform a standardized isometric external rotation test in a seated position with the elbow flexed at 90°.
Baseline
Muscle strength
Time Frame: Post-intervention (10 minutes)
Shoulder external rotator strength will be assessed using a handheld dynamometer (TruStrength, Hawkin Dynamics, USA), previously validated for measuring isometric muscle contraction strength. Participants will perform a standardized isometric external rotation test in a seated position with the elbow flexed at 90°.
Post-intervention (10 minutes)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Pain Pressure Thresholds - Latent MTrP
Time Frame: Baseline
The assessment of pressure pain thresholds (PPT) at the myofascial trigger point (MTrP) will be evaluated three times at each measurement site using a analog algometer, applying a pressure rate of approximately 5 N/s.
Baseline
Pain Pressure Thresholds - Latent MTrP
Time Frame: Post-intervention (10 minutes)
The assessment of pressure pain thresholds (PPT) at the myofascial trigger point (MTrP) will be evaluated three times at each measurement site using a analog algometer, applying a pressure rate of approximately 5 N/s.
Post-intervention (10 minutes)
Pain Pressure Thresholds - Tibialis anterior
Time Frame: Baseline
The assessment of pressure pain thresholds (PPT) at a distal location (Tibia's anterior) will be evaluated three times at each measurement site using a analog algometer, applying a pressure rate of approximately 5 N/s.
Baseline
Pain Pressure Thresholds - Tibialis anterior
Time Frame: Post-intervention (10 minutes)
The assessment of pressure pain thresholds (PPT) at a distal location (Tibia's anterior) will be evaluated three times at each measurement site using a analog algometer, applying a pressure rate of approximately 5 N/s.
Post-intervention (10 minutes)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Universidad Complutense de Madrid

Collaborators

Universidad Rey Juan Carlos

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 15, 2026

Primary Completion (Estimated)

June 30, 2026

Study Completion (Estimated)

July 30, 2026

Study Registration Dates

First Submitted

November 25, 2025

First Submitted That Met QC Criteria

November 25, 2025

First Posted (Actual)

December 8, 2025

Study Record Updates

Last Update Posted (Actual)

May 8, 2026

Last Update Submitted That Met QC Criteria

May 5, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UComplutenseMadrid-PENS

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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