This study aims to evaluate the effectiveness of neuromuscular electrical stimulation with superimposed voluntary contraction (NMES+ group) compared to NMES without voluntary contraction (NMES group) during the initial month of rehabilitation post anterior cruciate ligament reconstruction (ACLR). Forty patients will be randomly assigned to either the NMES group or the NMES+ group. Both groups will follow an identical rehabilitation regimen in the first month after surgery, which includes interventions for symptom management, inflammation control, edema reduction, improved joint motion range, and restoration of muscle function.

All participants will undergo identical assessment protocols at four time points: pre-surgery evaluation, and assessments at 2, 15, and 30 days post-ACLR. The primary outcome of the study is the maximal isometric strength of knee extensors. Secondary outcomes encompass thigh muscle atrophy, self-reported functional impairments, knee pain, knee edema, joint range of motion, and quadriceps activation status.

Inclusion Criteria:

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

Exclusion Criteria:

• Failure to attend the pre-surgery assessment session;
• 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.