Postural instability and balance challenges: Typically assessed through center of pressure (force plates); whole body measures are seldom done Cardinal symptom of PD and is a key risk factor of falls in Parkinson patients Traditionally examined in: older (frail) adults, post-stroke patients, and patients with Parkinson disease (PD) and other neurological conditions Compared between those who do or do not experience freezing of gait Has not been compared between two key PD subtypes: akinetic rigid and tremor dominant patients. Have also not been compared to healthy controls