Synergistic Effects of transcranial Direct Current Stimulation, transcranial Alternative Current Stimulation and Neuromuscular Electrical Stimulation Combined with Exercise Therapy on Clinical Outcomes and Electroencephalographic Activity in Women with Patellofemoral Pain Syndrome

Investigation and Comparison of the Synergistic Effects of tDCS, tACS, and NMES Combined with Exercise Therapy on Clinical Outcomes and EEG Activity in Women with Patellofemoral Pain Syndrome

A three-arm parallel, double-blind, randomized clinical trial conducted on 42 patients. Randomization was performed using the RAND function in Microsoft Excel

42 eligible women with patellofemoral pain syndrome will be randomly assigned to one of three intervention groups. Initial assessments will be conducted at the physiotherapy laboratory of the School of Rehabilitation. Subsequently, participants will undergo 12 treatment sessions, held three times per week over a continuous period of four weeks, at the physiotherapy clinic of the same school. Post-treatment assessments will be carried out after the completion of the intervention sessions and in one month followup. Both the participants and the physiotherapist responsible for pre- and post-treatment evaluations will be blinded to the group assignments.

Inclusion Criteria: Women aged between 18 and 35 years, A history of unilateral or bilateral pain around or behind the patella,Tenderness to palpation over the medial or lateral facet of the patella, Non-traumatic onset of symptoms Exclusion Criteria: History of knee injuries such as meniscal, tendon, or ligament damage, History of partial or complete patellar dislocation, Any musculoskeletal condition affecting other joints in the lower limbs or the backContraindications for the use of neuromodulation techniques

Group 1: NMES+Exe Group 2: tDCS+Exe Group 3: tACS+Exe

Pain intensity, Functional activity level, Functional performance, Dynamic balance, Mean relative and absolute power of the delta, theta, alpha1 and alpha2 frequency bands

All Eligible Patients will be Randomly Assigned Using Block Randomization with Blocks of Size 6, Equally Distributed into Three Groups (with an Allocation Ratio of 1:1:1): NMES+EX, tDCS+EX, and tACS+EX. The Group Allocation for Each Participant will be Concealed Using Sealed Envelopes.

This study is double-blinded. Both participants and the outcome assessor will be blinded to the group allocation. All assessments will be performed by a physiotherapist who is independent of the research team and will only work with participant codes. In the tDCS and tACS groups, 20-minute brain stimulation is delivered prior to the exercise in a seated and relaxed position, using a constant intensity of 2 mA. Electrode placement is identical in both groups. The device interface and settings are indistinguishable, and the display screen is masked to prevent revealing the type of current. Participants are informed that the study involves different types of brain stimulation without specifying which type. In the NMES group, electrical stimulation is applied simultaneously with strengthening exercises, which makes complete blinding of participants in this group not feasible. However, the assessor remains blinded throughout and is not involved in any part of the intervention.

It has been decided that the study protocol will be published as an article.

The start of the article protocol's access period depends on the journal review process and is not predictable.

Researchers in academic and scientific institutions

1. Permitted Analyses: Only analyses that align with the original aims of the study or that have been approved by the principal investigator and ethics committee are allowed. Secondary analyses must be related to public health or scientific research and must not attempt to re-identify individuals. 2. Permitted Use of Documents: Documents such as study protocols, informed consent forms, and anonymized data sheets may be used solely for scientific research, academic review, or regulatory purposes. Use for commercial purposes is strictly prohibited. 3. Governance Mechanisms: A data use agreement must be signed before any data is shared. All data sharing will comply with applicable ethical and legal guidelines, including data protection and confidentiality standards. Any publication resulting from the use of shared data must acknowledge the original study and its investigators

Individuals interested in receiving more information can contact the person responsible for the scientific correspondence of the study via email at karimpour-s@razi.tums.ac.ir.

After receiving and reviewing the applicant's request email, and in consultation with the supervising professors, the requested data will be sent as soon as possible.