Neuromuscular Control in Individuals Following ACL-Reconstruction

• Pre-treatment neuromuscular assessment Cortical Active Motor Threshed We will measure motor evoked potentials with the use of a Transcranial magnetic stimulator (MagStim model 200, Magstim Co., Ltd., Wales, UK). The MagStim has FDA 510K Clearance for stimulation of peripheral nerves.

• The participant will be asked to sit in the dynamometer (Biodex, System 3) in knee extension at 90 degrees of knee flexion.
• EMG electrodes will be placed on the distal quadriceps

o Local shaving, debridement, and cleaning will be done prior if necessary

• A non-latex swim cap will be placed on the participants head for investigator's measurements
• Briefly, a magnetic field with a maximum value of 2.2 Tesla will be introduced to the scalp at a location in the pre-motor cortex that corresponds to the quadriceps. Single pulse stimulations will be delivered with no less than 10 seconds between stimulations (maximum = 0.1 Hz).
• When the magnetic field is received at the premotor cortex at the appropriate area, a motor signal is sent to the quadriceps. We will record this signal with surface EMG electrodes that are on the quadriceps.
• The participant will be asked to extend their leg to match a force equivalent to 5% MVIC. Feedback will be provided to the participant to provide such force.
• Stimulation of the TMS will happen once every ten seconds until the Active Motor Threshold was found by the investigator.

• The motor evoked potential measured by the quadriceps will be recorded at 80%, 90%, 100%, 110%, 120%, 130%, 140%, and 150% of the patients Active motor threshold.
• Patient randomization

• The patient is then randomized to 1 of 2 treatment arms. 1) Visuomotor Therapy or 2) Passive Motion
• Perform Randomized Treatment Visuomotor Therapy

• The participant will sit in the Biodex chair with the tested limb secured in the dynamometer
• The participant will receive live real-time biofeedback of their knee force output (no more than 30% of maximum force)
• The participant will aim to match their force output to a target threshold presented on the screen.
• The participant will complete 10 60-second trials of this exercise with a 30 second rest between each trial.

OR

Passive Motion

• The participant will sit in the Biodex chair with the tested limb secured in the dynamometer
• The dynamometer will passively move the patients lower limb between 80 to 120 degrees of knee flexion
• The participant will be asked to relax for the duration of testing - The participant will complete 10 60-second trials of this exercise with a 30 second rest between each trial.
• Reassess Neuromuscular outcome (Step 1)
• 1-week washout period
• Repeat Steps 1 through 4 but the patient receives the cross-over arm intervention

Inclusion criteria

• • Ages 18-45

• At the time point of return to play progression following ACL Reconstruction
• Physically active individuals based on current ACSM guidelines of 30 minutes of moderate-intensity daily physical activity three days a week)

Exclusion criteria

• Subjects who are known to be pregnant (self-reported)

• Subjects diagnosed with malignancy
• Subjects with serious infection near the lower limb
• Subjects with known muscular abnormalities
• History of cardiopulmonary disorder
• Subjects with a previous history of stroke
• History of neurological or psychiatric disorders including poorly controlled migraine headaches, seizure disorder, history or immediate family history of seizures and/or epilepsy
• Subjects with any type of neuropathy (numbness and tingling)
• Subjects with a clinical diagnosis of multiple sclerosis (MS) or Parkinson's Disease
• Implanted biomedical device (active or inactive implants (including device leads), including deep brain stimulators, cochlear implants, and vagus nerve stimulators)
• History of skull fracture
• Subjects who have any metal implants anywhere in their head, neck or shoulders
• Patients taking any medications, which may influence cortical excitability, which could influence neurophysiologic measures) and affect objective clinical data (e.g. antispastics, anxiolytics, hypnotics, ant-epileptics)
• Subjects who are prescribed medications which may influence cortical excitability, which could influence neurophysiologic measures) and affect objective clinical data (e.g. antispastics, anxiolytics, hypnotics, ant-epileptics), will not be able to remain in the study.
• Unable to provide consent.