Dual Frequency Low-Level Laser Therapy in Myofascial Trigger Points of Upper Trapezius

Overview

The goal of this clinical trial is to learn if dual frequency low-level laser therapy (DF-LLLT) works to reduce pain and improve neck function in adults with myofascial trigger points in the upper trapezius muscle. It will also determine whether DF-LLLT improves cervical range of motion. The main questions it aims to answer are: i)Does DF-LLLT reduce pain intensity on the Visual Analog Scale (VAS) more than sham laser therapy? ii)Does DF-LLLT improve functional status (Neck Disability Index) and cervical range of motion more than sham laser therapy? Researchers will compare DF-LLLT plus conventional therapy to sham laser plus conventional therapy to see if DF-LLLT has greater therapeutic effects. Participants will: 1. Receive either DF-LLLT or sham laser therapy twice weekly for 4 weeks 2. Perform a standardized stretching and strengthening exercise program for the neck and shoulders. 3. Attend clinic visits at baseline, week 2, and week 4 for assessments of pain, function, and cervical mobility.

Myofascial trigger points (MTrPs) in the upper trapezius muscle are a frequent source of neck pain, muscle stiffness, and reduced cervical mobility. They are characterized by hypersensitive palpable nodules within taut muscle fibers that can produce local and referred pain. Traditional management strategies include stretching, strengthening, and various physical therapy modalities, but recurrence and incomplete relief are common. Low-level laser therapy (LLLT) is a non-invasive photobiomodulation technique shown to reduce pain and inflammation and promote tissue healing. Dual frequency LLLT may provide enhanced therapeutic effects compared to single frequency LLLT by delivering both continuous and pulsed light energy to targeted tissues. However, clinical evidence for its use in upper trapezius MTrPs is limited. This single-blinded randomized controlled trial will recruit 32 male and female participants aged 20-55 years who meet the diagnostic criteria for MTrPs according to Simons' guidelines. Participants will be randomly assigned to one of two groups: Experimental group: DF-LLLT (830 nm, 100 mW/cm², 9.12 Hz, 5 J/cm²) applied perpendicularly over each identified MTrP for 3 minutes 9 seconds per point, twice weekly for 4 weeks, plus a standardized stretching and strengthening program. Control group: Sham laser therapy with identical appearance and application time but without light emission, plus the same exercise program. Primary and secondary outcomes will be assessed at baseline, week 2, and week 4: Primary outcome: Change in pain intensity measured using the Visual Analog Scale (VAS) Secondary outcomes: Change in functional status (Neck Disability Index) and change in cervical range of motion (flexion, extension, lateral flexion, and rotation) measured with a goniometer. The study aims to determine whether DF-LLLT provides superior pain relief, functional improvement, and mobility gains compared to sham laser therapy when combined with conventional exercises. Statistical analysis will be performed using SPSS 21.0, with significance set at p ≤ 0.05.