Inclusion Criteria:  Men and women between 18 and 65 years old. To have at least 70º of knee flexion. Be aware of and accept the study criteria (informed consent). Healthy subjects, without previous hip or knee pathology or involved musculature.  Exclusion Criteria:  To have pain. Having pain in the quadriceps or hip at the time of the study. Currently following physiotherapy or analgesic treatment. Belenophobia (fear of needles). Recent surgery or trauma in the area. Pregnancy.