A split-belt treadmill (SBT) is a treadmill with two belts, whereby each leg can be driven at a different speed. Previous work by the investigators showed that one session of SBT training improved turning while multi-tasking and reduced FOG in PwPD tested in the laboratory. However, subsequent work raises questions as to whether treadmill improvements following repeated SBT training generalize to overground situations in the long term. Therefore, in this study, the investigators will perform a four-week SBT intervention with added practice of everyday turning scenarios (SBT+CP) or placebo exercise (SBT+PL), and study its effects on FOG in both the laboratory and at home.

• 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

Participants receive training in both arms and will be blinded to the exercise group differences.

Outcomes assessor will be blinded to the group allocation and will carry out all assessments in a standardized manner irrespective Investigator will perform blinded analyses of the data