Anticipatory postural responses prior to protective steps are not different in people with PD who do and do not freeze

For both forward and backward protective stepping, size and percentage trials with an APA were not statistically different between PD + FOG and PD-FOG, even after excluding converters from the PD-FOG group (p > 0.27 for all). No group by direction interactions were observed. These data suggest that, in mild to moderate PD, an inability to couple APAs with stepping, rather than an inappropriately sized APA, may be most related to freezing of gait.