Effects of Dry Needling on Latent Myofascial Trigger Points of the Extensor Digitorum Communis

Myofascial trigger points are hyperirritable spots located within a taut band of skeletal muscle. Latent myofascial trigger points do not cause spontaneous pain but may contribute to motor dysfunction, increased fatigability, reduced range of motion, and altered muscle performance. Dry needling is a commonly used physiotherapy technique for the treatment of myofascial trigger points. However, post-needling soreness is one of the most frequent adverse effects associated with this intervention and may influence patient comfort, adherence, and functional performance in the hours following treatment.

Electrical dry needling, also known as intramuscular electrical stimulation, combines dry needling with transcutaneous electrical nerve stimulation applied through the inserted needle. Different modalities of electrical dry needling are used in clinical practice, including bipolar and monopolar applications. Nevertheless, limited evidence is available regarding the effect of these techniques on post-needling soreness, particularly when short-duration monopolar stimulation is applied using a pointer-type device.

The aim of this randomized single-blind clinical trial is to compare the effects of different dry needling and electrical dry needling techniques applied to latent myofascial trigger points in the extensor digitorum muscle of the dominant forearm in healthy adults. The primary objective is to compare the effect of electrical dry needling versus Hong fast-in and fast-out dry needling on the intensity and duration of post-needling soreness. Secondary objectives include comparing post-needling soreness among the different dry needling techniques, analyzing immediate changes in handgrip strength, assessing changes in finger flexion and wrist palmar flexion range of motion, evaluating pain during the needling procedure, assessing pressure pain threshold by algometry, and analyzing perceived comfort and interference of post-needling soreness with daily activities.

Healthy adults with a latent myofascial trigger point in the extensor digitorum muscle of the dominant forearm will be recruited. Participants will be randomly assigned to one of five groups: control group, Hong fast-in and fast-out dry needling group, rotational dry needling group, bipolar electrical dry needling group, or monopolar electrical dry needling group. Participants in the control group will not receive any dry needling intervention but will undergo the same assessment schedule as the intervention groups.

In the Hong fast-in and fast-out dry needling group, a sterile needle will be inserted into the latent myofascial trigger point and repeated fast-in and fast-out movements will be performed. In the rotational dry needling group, a sterile needle will be inserted into the latent myofascial trigger point and a rotational dry needling technique will be applied according to the study protocol. In the bipolar electrical dry needling group, a sterile needle will be inserted into the latent myofascial trigger point, an adhesive electrode will be placed near the needle, and a TENS current will be applied for 15 minutes. In the monopolar electrical dry needling group, a sterile needle will be inserted into the latent myofascial trigger point and stimulation will be applied using a Pointer Plus Excel-II device for 3 minutes.

Outcome assessments will be performed at baseline and 5 minutes after the intervention. Post-needling soreness intensity and duration will also be recorded at 24, 48, and 72 hours after the intervention. The study will use separated roles for recruitment, assessment, intervention delivery, and data analysis in order to reduce bias. Outcome assessors and the researcher responsible for data analysis will be blinded to group allocation.

Inclusion criteria

• Adults aged 18 to 40 years.
• Healthy participants with a latent myofascial trigger point in the extensor digitorum muscle of the dominant forearm.
• No pathology affecting the upper limb where the intervention will be applied.
• No episode of pain in the upper limb during at least the previous two months.
• No contraindications to dry needling or electrical dry needling techniques.
• Voluntary signature of the informed consent form.
• Willingness to follow the protocol proposed by the research team.

Exclusion criteria

• Needle phobia.
• Coagulation disorders.
• Pregnancy.
• Thyroid disorders.
• Altered skin integrity in the treatment area.
• Epilepsy.
• Local or systemic infection.
• Diagnosed neurological disorders affecting pain perception or neuromuscular function in the region of interest, such as multiple sclerosis or peripheral neuropathies.
• Generalized chronic pain conditions, such as fibromyalgia.
• Weekly use of analgesic medication, including anti-inflammatory drugs, opioids, or other pain-relieving medication.