Bioimpedance and Sensorimotor Effects of Percutaneous Electrolysis Protocols on the Patellar Tendon

Percutaneous electrolysis is a physical therapy technique, whose main objective is the treatment of the signs and symptoms associated with tendinopathies by applying a galvanic current through a blunt dry needle. Despite its clinical use being already stablished, the physiological mechanisms underlying this therapy are still unknown and thus, the optimal parameterization. The present study proposes to perform different stimulation protocols of percutaneous electrolysis on healthy subjects patellar tendon to answer those questions.

Intervention will be performed in the middle of the patellar tendon, using ultrasonography to guide the needle insertion, without risk of affecting any adjacent structure. The theoretical basis of the technique is to produce specific controlled changes in the intervened tissue, and the pathological symptoms, through the accumulation of an electric charge. For this reason, the protocols will be the following:

1. High-intensity and short-duration: 3 squared pulses of a high intensity galvanic current (3 mA) for 3 seconds with 3 seconds rests between pulses and 1 second of pulses ramp. The current will be off during the first 348 seconds of the intervention and the last 18 seconds it will be on. The total intervention time will be 366 seconds.
2. Low-intensity and long-duration: 3 squared pulses of a low intensity galvanic current (0.1 mA) during 90 seconds, with 3 seconds rests between pulses and 30 seconds of pulses ramp. The total intervention time will be 366 seconds.
3. High-intensity, short-duration and 20 Hertz (Hz): 3 squared pulses of a high intensity compensated biphasic squared current (3 mA), during 3 seconds with 3 seconds rests between pulses and 1 second of pulses ramp. The alternative frequency of 20 Hz and the pulse width of 50 ms. The current will be off during the first 348 seconds of the intervention and the last 18 seconds it will be on. The total intervention time will be 366 seconds.
4. Sham electrolysis group will got the same intervention, but without applying electrical current.

The study design will be an crossover clinical trial, with randomized order of intervention with repeated measurements. Therefore, each subject will be have the four protocols at randomized order, with a gap of at least one week between them. The study will be full blinded.

The capacity to recruit the inhibitory system will be evaluated by means of conditioned pain modulation. Moreover, somatosensory thresholds will be evaluated in the knee, as well as knee extension strength. In addition, we will undertake continuous measures of the electrical bioimpedance of the patellar tendon, to study the changes produced by the intervention in the different intra and extracellular tissue components.

The conditioned modulation of pain assesment will take place one week before to the intervention, and the remaining measurements will be measured pre-intervention and post-intervention for each protocol.

Eligibility Criteria:
Inclusion Criteria:

* Healthy.
* Between 18 and 45 years old.

Exclusion Criteria:

* to suffer or to have suffered any pathology on the arm on the last 30 days.
* to suffer some disease discouraging current application or needling, as coagulation deficit, etc.
* to suffer some severe disease as diabetes mellitus, cancer, neurology disease, depression, fibromyalgia, etc.
* to suffer some cognitive disorders.
* to consume drugs as coagulants, anti-depressant, pregabalin, neuropeptide, opioids, etc during investigation or the first week before investigation.
* to consume NSAIDS the last 48 hours before investigation or during investigation.
* belonephobia.
* To consume caffeine 2 hours prior to the investigation or perform intense exercise on the same day as the measurement.
* To receive concomitant physical therapy treatments or have previously received percutaneous electrolysis treatment.
* professional athlete
* To be pregnant.