All participants received a standardized pre-treatment protocol consisting of 10 minutes of massage therapy to the triceps surae, 5 minutes of subtalar joint mobilization, and 10 minutes of radiofrequency diathermy (0.5 MHz, capacitive mode) prior to needle insertion.

All participants received a standardized pre-treatment protocol consisting of 10 minutes of massage therapy to the triceps surae, 5 minutes of subtalar joint mobilization, and 10 minutes of radiofrequency diathermy (0.5 MHz, capacitive mode) prior to needle insertion.

All participants received a standardized pre-treatment protocol consisting of 10 minutes of massage therapy to the triceps surae, 5 minutes of subtalar joint mobilization, and 10 minutes of radiofrequency diathermy (0.5 MHz, capacitive mode) prior to needle insertion.

A sterile, disposable stainless steel needle of different lengths depending on the area to be treated will be connected to the EP device; the gauge of these needles will be 0.25 mm. A current of 3 mA will be applied for 3 times with a duration of 3 seconds each. In order to avoid biases, the technique will be performed for 90 seconds as in the low intensity treatment group and in the last 20 seconds the current will be applied with the parameters previously described. Three sessions divided in three consecutive weeks will be applied.

Pain assessment of participants' pain in both upright and contracted positions will be performed using a 10-point Verbal Numerical Pain Scale (0=no pain, 10=maximum pain tolerable). Subjects will be asked to rate numerically the pain at rest and in a maintained position of elevation of both heels, also commonly known as "standing on tiptoe". In the latter position, 10 will be considered if the subjects fail to stand in this position for at least one complete elevation.

Pain assessment of participants' pain in both upright and contracted positions will be performed using a 10-point Verbal Numerical Pain Scale (0=no pain, 10=maximum pain tolerable). Subjects will be asked to rate numerically the pain at rest and in a maintained position of elevation of both heels, also commonly known as "standing on tiptoe". In the latter position, 10 will be considered if the subjects fail to stand in this position for at least one complete elevation.

Recovery from painful injuries is associated with fear of movement or also called kinesiophobia. It could be defined as an irrational or excessive fear of movement for fear of injury or re-injury. That is why a kinesiophobia questionnaire (Annex II) will be provided at the beginning of the study (day I, assessment and first intervention) to all participants to assess kinesiophobia to perform certain movements that may cause pain or worsen previous injuries. It consists of 11 questions with a minimum score of 11 and a maximum score of 44.

The evaluation of this variable will be carried out by measuring the angle extracted from the dorsiflexion of the ankle with a knee extension. This stretch is commonly performed in sports practice so patients are generally already familiar with it. The stretches will be performed with the participants barefoot. Likewise, the participants will be instructed on the positioning of the test. The leg to be evaluated will be placed in such a way that the foot is placed in the midline of an area marked on the floor, and the foot of the healthy leg will be placed forward at the distance of one step. The end point of the gastrocnemius stretch will be defined as the point at which the participants feel discomfort without lifting the heel and without pelvic rotation.