Diacutaneous fibrolysis is a physiotherapeutic instrumental technique, used to treat musculoskeletal conditions causing pain and/or movement restriction. It is applied by means of metallic hooks, ending in a spatula with beveled edges, that seems to allow a better pressure distribution on the skin and a deeper and more precise application, compared to the manual approach. Recent studies indicate positive responses regrading pain intensity decrease in sports people suffering anterior knee pain, improving range of motion in subacromial impingement syndrome, improving sensory conductivity in symptomatic patients with carpal tunnel syndrome, decreased pain in patients with chronic epicondialgia or improveing function athletes with anterior knee pain. However, the specific action mechanism, have not been investigated in depth yet. There are no studies evaluating its effects on posterior muscular chain of lower extremity in athletes, where FD effects on neuromuscular response could be more evident due to the overload involved on this area. The aim of this study is to evaluate the immediate, and after 30 minutes, effects of a single diacutaneous fibrolysis session on flexibility, strength and neuromuscular activity on hamstring in athletes. A randomized controlled trial with blind evaluator. Randomization will be done between lower extremities of each subject (Random.org). Regardless of its own dominance, diacutaneous fibrolysis will be applied to de following muscles and intermuscular septums: gluteus maixmus, biceps femoris and semitendinosus to de lower experimental limb. The other extremity will not be treat (control limb).

Sample recruitment. Athletes from UIC university community, who compete officially or institutionally, whether they are federated or recorded in a sport official register where the predominant activity focuses on the lower train (athletics, cycling, football, rugby...). Procedure. The anthropometric data will be collected at the beginning of the study. Each outcome assessment will be performed by a blinded evaluator at the baseline, immediately after the technique application and 30 minutes after.

Inclusion Criteria:

• Athletes
• <160º in the Passive Knee Extension test
• Participants must sign and have informed consent.

Exclusion Criteria:

• Poor skin
• Trophic condition
• Taking anticoagulants
• Inflammatory process
• Recent musculoskeletal lower limb injury (< 6 month)

The assessor will not know if patient have received the treatment or not