Brief Summary:

This project consists of two sequential experimental phases designed to analyze the immediate and 24-hour effects of three invasive physiotherapy techniques -dry needling (DN), percutaneous neuromodulation (PENS), and percutaneous electrolysis (EPE)- on muscle tone and pain perception.

In the first phase, the study will be conducted on healthy volunteers to assess the physiological responses and safety profile of the interventions under controlled conditions. Each participant will receive one of the three randomly assigned interventions (DN, PENS, or EPE), applied to the upper trapezius muscle. Pain perception (Visual Analog Scale, VAS) and muscle mechanical properties (tone, stiffness, and elasticity) will be measured before and after the intervention, and after 24 hours, using the MyotonPRO device.

In the second phase, the same protocol and parameters will be applied to patients with chronic neck pain, in order to compare the magnitude and persistence of the effects between healthy subjects and symptomatic individuals.

This study aims to improve understanding of the short-term physiological mechanisms of invasive physiotherapy techniques and their relative effectiveness in managing chronic neck pain. The findings will contribute to the development of more precise and evidence-based treatment protocols for musculoskeletal pain.

INCLUSION CRITERIA Phase 1 - healthy subjects

1. Age between 18 and 65 years.
2. Healthy individuals without any current musculoskeletal or neurological pathology.
3. Presence of a palpable myofascial trigger point in the upper trapezius muscle.
4. No neck or shoulder pain requiring medical treatment in the past three months.
5. Willingness to refrain from other physiotherapy or manual therapy interventions during the study period.
6. Ability to understand and provide written informed consent

Phase 2 - Patients with Chronic Neck Pain

1. Age between 18 and 65 years.
2. Diagnosis of chronic mechanical or tension-type neck pain lasting for at least 3 months.
3. Presence of at least one active myofascial trigger point in the upper trapezius muscle.
4. Pain intensity between 3 and 7 on a 10-cm Visual Analog Scale (VAS) at baseline.
5. No previous invasive physiotherapy treatments (dry needling, electrolysis, or neuromodulation) within the last 4 weeks.
6. Ability and willingness to attend all study sessions and follow-up assessments.
7. Signed informed consent before participation.

EXCLUSION CRITERIA

1. History of cervical or shoulder surgery.
2. Neurological, systemic, or rheumatologic disorders affecting the cervical or upper limb region.
3. Anticoagulant therapy or known bleeding disorders.
4. Pregnancy or suspected pregnancy.
5. Skin infection, wound, or dermatological condition at or near the intervention site.
6. Use of analgesic, anti-inflammatory, or muscle relaxant medications within 48 hours prior to the intervention.
7. Prior invasive physiotherapy (dry needling, PENS, or EPE) in the target area during the past month.
8. Contraindications to electrical stimulation (for PENS or EPE groups), such as implanted pacemaker or metal implants near the treatment area.
9. Fear of needles (trypanophobia) or intolerance to invasive procedures.
10. Participation in another clinical trial within the past 3 months.
11. Refusal or inability to provide informed consent