Split-belt Treadmill Training for Freezing of Gait in Parkinson's Disease

* Be between 40 - 90 years of age * Have a diagnosis of Parkinson's disease * Be able to walk for 10 min without an aid * Be able to follow and understand the oral instructions of the investigator * Have a disease stage of I to IV (while ON-medication) * Have had no change in your Parkinson's medication in the past month (or to your deep brain stimulator if applicable) and also no planned changes in medication over the next 4 months * Have at least about 1 "freezing" episode per day (based on the New Freezing of Gait Questionnaire: N-FOG) * Not participating in another clinical trial * Have no acute joint disease * Not have any other condition that affects your walking pattern or prevents you from completing all study tasks * Have not undergone major surgery or hospitalization in the last 3 months * No substance abuse * No depressive disorder or other apathetic disorder that precludes daily exercise