Mechanical compression is applied with the thumb to the upper trapezius muscle on the non-dominant side at the midpoint between the acromion and C7. The intensity of this will be regulated by the pain it causes the patient, trying to ensure that it is at all times approximately 5/10 on the numerical pain rating scale (NPRS) with 0 being "no pain at all" and 10 being "the worst pain imaginable". The stimulation will be carried out for 2 minutes.

To perform this procedure a TENS will be used applying a biphasic current, since it is the most used and studied type of electrotherapy. A frequency of 100hz and a bandwidth of 150 will be used. The intensity will be increased and decreased with the patient's feeback in order to provoke a pain of approximately 5/10 in the NPRS. The stimulation will be performed for 2 minutes on the upper trapezius of the non-dominant side at the midpoint between acromion and C7.

The non-dominant hand shall be placed in a bucket of cold water at 10.5° for 2 minutes.

Pain stimulus on non-dominant side

PPTs will be assessed on the dominant side over the tibialis anterior muscle using a digital algometer (Wagner instruments, Greenwich, CT, USA). Participants will be instructed to say "stop" when the pressure sensation becomes painful. The average of 3 assessments on the tibialis anterior of the dominant side will be performed for analysis. The algometer pressure for assessment will be gradually increased at a rate of 1kg/second. Data will be collected in kg/cm2.