Trigger points (TrPs) are a common musculoskeletal cause of local and referred muscle pain, as well as local inflammation in the muscle and fascia. From a clinical and sensory viewpoint, TrPs may be classified as active or latent. The principal difference is the reproduction of symptoms experienced by an individual (active) with or without stimulation. Local and referred pain elicited from latent TrPs may be transient in duration upon stimulation, and latent TrPs may be present without spontaneous symptoms.

Both active and latent TrPs induce motor dysfunctions such as stiffness, restricted range of motion, and accelerated fatigability in the affected muscle. The interrater reliability of manual identification of latent TrPs in the calf muscles has been found to range from small to moderate. The clinical relevance of latent TrPs has increased in the last decade,4 and some studies have investigated the effects of treating them. Among all manual therapies targeted to latent TrPs, ischemic compression, or TrP pressure release, is the most commonly used. Although TrPs may affect any muscle, the gastrocnemius muscle may be the most susceptible in the lower extremity to developing them. It has been reported that 13% to 30% of the asymptomatic population has latent TrPs in these muscles, and their presence may affect sport practice.

The purpose of this study will be to evaluate changes in neuromuscular function, pain perception, and basic physical properties in myofascial trigger points (TrPs) after a single treatment session of dry needling in the gastrocnemius muscle.

A randomized within-participant clinical trial with a blinded assessor will be conducted. 50 asymptomatic volunteers (100 gastrocnemius-muscle) with MrPs gastrocnemius-muscle TrPs will bilaterally explored. Each extremity will be randomly assigned to the control group (no treatment) or the experimental group (60 seconds of dry needling over each TrP). Neuromuscular function of the gastrocnemius muscle will be assessed using a MyotonPro and a tensiomyography. Muscle flexibility will be analyzed using the lunge test and the passive ankle range of motion. The strength will be determined with a handheld dynamometer (MicroFET2). Pain perception will be analyzed with a 0-to-10 numerical pain rating scale and determination of pressure pain thresholds over each latent TrP.

Inclusion Criteria:

• A TrP will be diagnosed using the following criteria: palpable taut band, presence of a painful spot in the taut band, and referred pain on palpation of the spot.

Exclusion Criteria:

• Participants were excluded if they reported any pain symptoms in the lower extremities in the previous year.
• They were also excluded if they presented previous surgical interventions, previous lower-extremity injury, any underlying medical disease, pregnancy, or muscle soreness after vigorous exercise.

the assessor will not know if patients have received the dry needling technique or not.