This intervention consisted in the application of an asymmetric biphasic rectangular current. The subject lay prone with her feet outside the table. The FHL muscle was located at 50% of the distance between the fibular head and inferior border of the lateral malleolus on the posterior aspect of the fibular by ultrasound machine (cross-section) (Logiq, GE Healthcare, USA) and then, a needle (0.30mm x 0.40mm) was inserted, perpendicular to the surface of the skin, until the muscle belly. Prior to inserting a neddle, the underlying skin was cleaned with isopropyl alcohol. The intensity of the current was necessary to cause an exacerbated muscle contraction, during 1.5 min acording to the Valera and Minaya protocol´s.

This intervention was performed once in each participant, on one leg only (stance limb), It's only once, it was not a treatment

This intervention consisted in the application of an asymmetric biphasic rectangular current. The subject lay prone with her feet outside the table. The FHL muscle was located at 50% of the distance between the fibular head and inferior border of the lateral malleolus on the posterior aspect of the fibular by ultrasound machine (cross-section) (Logiq, GE Healthcare, USA),and then, one self-adhesive electrode was placed on the back of the leg and the other on the sole of the foot. The intensity of the current was necessary to cause an exacerbated muscle contraction, during 1.5 min.

This intervention was performed once in each participant, on one leg only (stance limb), It's only once, it was not a treatment

This intervention consisted in the application of an asymmetric biphasic rectangular current of 150 microseconds and 10 Hz using a specifically developed medically certified device (Physio Invasive, Enraf Nonius, Prim, SPAIN). This is an invasive intervention by ultrasound and needles.

Assessed by a single leg balance test

Assessed by endurance test (heel raise repetitions).

Assessed using goniometer.