To develop a reliable and accurate clinician-reported outcome (ClinRO) measure (against a new and precise definition) and patient reported outcome (PRO) for use by clinicians and researchers to quantify the severity of Freezing of Gait (FOG).

Inclusion Criteria:

1. Diagnosis of idiopathic Parkinson's disease (PD) made by a neurologist according to the Movement Disorders Society guidelines;
2. Able to walk independently for a distance of 10 meters, without walking aid;
3. Absence of a Deep Brain Stimulator;
4. Stable PD treatment in the 4 weeks prior to participation that is not expected to change in the course of the study.
5. For patients with FOG: a score of ≥ 1 on the New Freezing Of Gait Questionnaire (NFOG-Q).

Exclusion Criteria:

1. Occurrence of any of the following within 3 months prior to informed consent: myocardial infarction, hospitalization for unstable angina, stroke, coronary artery bypass graft (CABG), percutaneous coronary intervention (PCI), implantation of a cardiac resynchronization therapy device (CRTD), active treatment for cancer or other malignant disease, uncontrolled congestive heart disease (NYHA class >3), acute psychosis or major psychiatric disorders or continued substance abuse, other neurological (than PD) or orthopaedic impairment that significantly impacts on gait.
2. Unwilling to temporarily delay the morning anti-Parkinsonian medication.
3. Preganacy and

FOG & NON-DOG