Effect of US-Guided PNM in CrossFit With Nonspecific Shoulder Pain

August 25, 2025 updated by: Alberto Carcasona Otal, Universidad de Zaragoza

Changes in Shoulder Strength, Mobility, and Muscle Recruitment Following Ultrasound-Guided Percutaneous Neuromodulation in CrossFit Athletes With Nonspecific Shoulder Pain: A Randomized Controlled Trial

CrossFit is a high-intensity physical training program that combines exercises from various disciplines, such as weightlifting, track and field, running, and gymnastics. The three main characteristics of this sport discipline are as follows: first, the execution of functional movements; second, performing them at high intensity; and lastly, constant variation. This training model has shown improvements in strength, power, balance, flexibility, and cardiorespiratory capacities.

There are various risk factors described in the literature that may lead to injuries in CrossFit athletes. It has been suggested that demanding training programs increase this risk, especially when performed incorrectly (poor technique). Additionally, excessive training load and frequency can lead to early fatigue, greater perceived effort, and risky movement execution.

On the other hand, older age, male sex, and previous injuries also appear to be relevant risk factors, as well as performing stretches prior to CrossFit practice. Several studies have shown that the shoulder is the joint with the highest prevalence of injury in this sport, surpassing other commonly affected joints such as the lumbar spine or the knee.

Among the wide variety of injuries related to the shoulder, the diagnosis of "nonspecific shoulder pain" has a high prevalence in the adult population. This term is used to describe clinical cases where it is not possible to identify the specific cause of the pain, and is justified by its multifactorial etiology, which is associated with several risk factors. These include: imbalance in the strength ratio between internal and external rotators, limitations in rotational mobility of the glenohumeral joint, deficits in motor control of the scapular musculature, shoulder muscle fatigue, and the repetitive execution of overhead exercises.

This last factor is especially relevant in the CrossFit population, as such movements are frequent in the discipline. Repeated overhead exercises have been associated with a deficit in glenohumeral internal rotation. From a biomechanical perspective, this movement is more efficient when accompanied by external rotation, so internal rotation limitation can compromise the motion. This deficit has been linked to modifiable musculoskeletal factors such as posterior capsule stiffness, shortening of the infraspinatus or teres minor muscles, and scapular mechanics alterations, as well as non-modifiable factors like bone torsion observed in young athletes. These conditions can lead to pain and/or glenoid labrum pathology.

Regarding the clinical management of nonspecific shoulder pain, conservative physiotherapy treatment is the most common approach. This is based on manual therapy and therapeutic exercise. However, in recent years, invasive physiotherapy has gained popularity in the treatment of musculoskeletal disorders through techniques such as ultrasound-guided percutaneous neuromodulation (US-guided PNM). This technique involves delivering electrical stimulation through an acupuncture needle placed near the nerve (epineurium) or the motor point of the target muscle, aiming to restore proper functionality of pathological neuromuscular structures.

US-guided PNM, applied to both the lower and upper limbs, has shown effectiveness in both healthy individuals and subjects with various musculoskeletal disorders, improving pain, strength, flexibility, and normalization of neural excitability.

Currently, there are therapeutic exercise protocols used for both evaluation and treatment of nonspecific shoulder pain in CrossFit athletes. Additionally, there are US-guided PNM protocols that have been applied to healthy CrossFit athletes and have demonstrated improvements in shoulder rotational strength. However, US-guided PNM has not yet been studied in a population of CrossFit athletes with nonspecific shoulder pain. Therefore, this randomized clinical trial aims to evaluate the effectiveness of two different US-guided PNM protocols, analyzing which methodology is most appropriate for reducing the risk factors associated with the development of nonspecific shoulder pain in CrossFit athletes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
42

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Spain
    • Zaragoza
      • Zaragoza, Zaragoza, Spain, 50009
        • University of Zaragoza

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion criteria:

  • Be over 18 years old.
  • Have shoulder pain lasting more than 3 months.
  • The pain must not have an apparent cause, meaning there is no specific diagnosis, and thus it is considered nonspecific pain.
  • Train CrossFit at least 3 days per week.

Exclusion criteria:

  • Have received any medical or physiotherapy treatment for nonspecific shoulder pain.
  • Have had previous shoulder surgery.
  • Present fear of needles (belonephobia) or fear of the US-guided PNM intervention.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: US-guided PNM 10 Hz
One session of US-guided PNM at a frequency of 10 Hz.
Other: Ultrasound Guided Percutaneous Neuromodulation. Frequency of 10 Hz
The US-guided PNM intervention will be performed with the patient in the prone position, the shoulder to be treated flexed at 90 degrees, the humerus partially supported on the table, the elbow flexed at 90 degrees, and the musculature relaxed. Needles will be inserted near the perineurium of the axillary and suprascapular nerves. Prior to needle insertion, the skin will be cleaned with isopropyl alcohol and chlorhexidine. The PNM intervention will consist of applying a compensated asymmetric biphasic current, with a rectangular positive phase and a triangular negative phase, at a frequency of 10 Hz, pulse width of 240 μs, and the maximum tolerated intensity that elicits a painless maximal muscle contraction, following this protocol: 10 stimulations of 10 seconds each, with a 10-second rest between stimulations.
Experimental: US-guided PNM 1 Hz
One session of US-guided PNM at a frequency of 1 Hz.
Other: Ultrasound Guided Percutaneous Neuromodulación. Frequency of 1 Hz
Same intervention as previously described, with the only difference being that the frequency will be 1 Hz instead of 10 Hz.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Strength ratio between ER/IR
Time Frame: The measurements were taken pre-intervention and immediately post-intervention.
A hand-held dynamometer (HHD) with units in kg of force (KgF) was used. The participant was positioned according to the instructions of Hams et al., seated with the hip and knee flexed at 90 degrees, feet flat on the floor, trunk upright, shoulder at 0 degrees of abduction and neutral rotation, and elbow in contact with the trunk, flexed at 90 degrees. The dynamometer was placed on the distal third of the inner forearm to assess internal rotation (IR) and on the distal third of the outer forearm to assess external rotation (ER). Athletes were instructed to produce the maximum isometric force for 10 seconds, while the evaluator applied the same force in the opposite direction. Three tests were performed bilaterally, with a one-minute rest between each test, and the final data was the average of the three tests. The strength ratio was calculated by dividing ER/IR, with 2:3 (0.66) considered the ideal ratio.
The measurements were taken pre-intervention and immediately post-intervention.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Glenohumeral rotational mobility
Time Frame: The measurements were taken pre-intervention and immediately post-intervention.
A digital goniometer (HALO), which has demonstrated validity and reliability for measurements in the shoulder joint, was used. For each participant, bilateral internal rotation (IR) and external rotation (ER) were measured. Subsequently, both rotations were summed to create a third variable: the total rotational movement arc (ART). The patient was placed in the supine position, with the shoulder abducted at 90 degrees, the elbow flexed at 90 degrees, and the forearm perpendicular to the floor. An evaluator stabilized the scapula by applying pressure to the coracoid process, while another evaluator performed passive internal/external rotation and placed the goniometer on the distal third of the forearm on its dorsal side. Passive mobilization was completed when the first "end-feel" was reached or when the scapula began to move. Two measurements of each rotation were taken on each shoulder, and the final data was the average of both measurements.
The measurements were taken pre-intervention and immediately post-intervention.
Scapular motor control
Time Frame: The measurements were taken pre-intervention and immediately post-intervention.
A surface electromyograph from the commercial brand Mdurance, which has been validated and used in the literature, was used. According to Kibler et al., proper scapular motor control is primarily achieved through the upper and lower trapezius muscles and the serratus anterior. Therefore, surface electrodes were placed bilaterally on the three muscles mentioned, and the athlete was asked to perform five repetitions of glenohumeral abduction in the scapular plane. The electromyograph software recorded the activation level of the three muscles, as well as the order of activation of the musculature.
The measurements were taken pre-intervention and immediately post-intervention.

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Universidad de Zaragoza

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Aragon Institute for Health Research (IIS Aragón)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Alberto Carcasona, Physiotherapist, IIS Aragón, University of Zaragoza

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 31, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 19, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 25, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 6, 2025

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 2, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 25, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NMP-e, CrossFit, dolor hombro

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Data will be shared on a reasonable request contacting with the main author once data has been published.

Anyway, Individual participant data (IPD) will be shared with other researchers in accordance with data sharing protocols and participant consent, ensuring confidentiality and ethical considerations are maintained.

IPD Sharing Time Frame

Once research has been published

IPD Sharing Access Criteria

Study protocol will be publish in a scientific journal

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

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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