This study aims to investigate the effects of eccentric training on the functional rehabilitation of patients undergoing Anterior Cruciate Ligament Reconstruction (ACL-R). Thirty-four participants undergoing ACL-R will be randomly assigned to two groups: the Conventional Training Group (CTG) and the Eccentric Training Group (ETG). Both groups will adhere to the same post-surgical rehabilitation program, commencing in the first week after ACL-R and continuing until the criteria for sports resumption are achieved. The rehabilitation program will be structured into four phases: immediate post-operative, preparatory, general acquisition, and specific acquisition. The key distinction between the groups lies in their exercise regimen: ETG will prioritize the eccentric phase of movement, whereas CTG will engage in conventional exercises, maintaining uniform load across both movement phases. Assessment procedures will be conducted at three intervals for all participants: immediately post-operative, at 12 weeks post-ACL-R surgery (before the initiation of the training protocol), and at 25 weeks post-ACL-R surgery (upon completion of the training protocol). The primary outcome measure will be the maximum isometric strength of knee extensors. Secondary outcomes will encompass functional status, maximum isometric strength of knee flexors, peak dynamic strength during leg press, quadriceps muscle atrophy, performance in jump tests, and psychological readiness.

Inclusion Criteria:

- Individuals of both genders, aged between 18 and 40 years, scheduled for ACL reconstruction surgery during the data collection period.

Exclusion Criteria:

• Delay of more than 7 days after surgery to initiate the rehabilitation program proposed by the study;
• Presence of injuries related to the rupture of the ACL that hinder partial weight-bearing in the first week after surgery, either due to medical recommendation or the patient inability/disposition.