The Anterior Cruciate Ligament (ACL) is vital for knee stability, and ACL injuries in futsal can lead to long-term issues. Reconstruction surgery may be affected by Anthrogenic Muscle Inhibition (AMI), especially in the vastus medialis muscle. This study aims to compare AMI in futsal players with ACL injuries to those without injuries, focusing on measurement techniques, sports performance, muscle strength, and recovery time. The research involves evaluating 54 players (27 injured and 27 non-injured) at various stages of the season using strength tests and imaging.

Introduction: The Anterior Cruciate Ligament (ACL) is crucial for knee stability and represents a major challenge in sports such as futsal. ACL injuries can carry a risk of long-term complications. While reconstruction surgery is a common method for recovery, it can be affected by Anthrogenic Muscle Inhibition (AMI), especially in the vastus medialis. Research on AMI in futsal players will be fundamental to improve rehabilitation, functionality, and reduce the risk of relapse.

Objectives: To analyze the changes in the Anthrogenic Muscular Inhibition of the vastus medialis in futsal players with Anterior Cruciate Ligament Injury compared to non-injured players. The specific objectives include evaluating measurement techniques, assessing the impact on sport quality, assessing muscle strength, and examining recovery time.

Methodology: The present study uses an observational cohort design to evaluate AMI in indoor soccer players at different stages of the soccer season, compared to players who suffer ACL injuries during competition. The sample size is 54 subjects, with 27 in each group. Accounting for a 15% loss, the final sample will be 64 subjects (32 in each group). Players will be evaluated for isometric strength by electromyography, strength in extensors, single leg vertical jump test, and ultrasound evaluation. These measurements will be taken for all players in the pre-season, after 4 months, and at the end of the season. For ACL injuries, evaluations will be conducted pre-operation, 4 months post-operation, and at the end of the soccer year.

Key words: Anthrogenic Muscle Inhibition, soccer, Anterior Cruciate Ligament, Rehabilitation.

Inclusion Criteria:

• Age between 18 and 45 years old
• Playing in the Spanish National League (first or second category) or in the Madrid Futsal Federation in PRIMERA RFFM and PREFERENTE.
• Both sexes
• Have been playing futsal for at least 2 years
• Enrolled in the Madrid Health System
• Any language

Exclusion Criteria:

• Operations other than an Anterior Cruciate Ligament injury (Cartilage, Meniscus, Ligaments).
• Injuries to the knee of the contralateral lower limb. (sprains, fracture)
• Muscle injuries or conditions in the affected or contralateral limb for less than 2 months (sprains, tibial periostitis, tendinopathies, tears).
• Any infection must be reported after the intervention and will be excluded from the study.
• Players will not be allowed to play any kind of team sport other than Futsal in an official way during this season.
• Players may not have any cardiovascular or respiratory pathology that would affect the study.
• Players who have already undergone an Anterior Cruciate Ligament rupture in previous years will not be considered.

The study population consists of futsal players aged 18-45. This includes two groups: (1) players without ACL injuries who serve as a comparison group, and (2) players who have sustained ACL injuries and are undergoing or have undergone ACL reconstruction surgery. The study aims to compare Anthrogenic Muscle Inhibition (AMI) and muscle function between these two groups.