People with Parkinson disease (PD), both “freezers” and “non-freezers,” had similar forward and backward gait velocity, according to a recent study that examined exercise's effects on gait performance. The study investigated neural correlates related to these effects, and potential neural activation differences between freezers and non-freezers during motor imagery (MI) of gait. 37 participants from a larger exercise intervention completed behavioral assessments and functional magnetic resonance imaging (fMRI) scans before and after a 12-week exercise intervention. Gait performance was characterized using gait velocity and stride length, and a region of interest (ROI) fMRI analysis examined task-based blood oxygen-level dependent (BOLD) signal changes of the somatomotor network (SMN) during MI of forward (IMG-FWD) and backward (IMG-BWD) gait. Researchers found:

• Velocity (F(1,34) = 55.04) and stride length (F(1,34) = 77.58) were significantly lower for backward vs forward walking in all participants.
• The ROI analysis showed freezers had lower BOLD signal compared to non-freezers in the cerebellum [F(1,32) = 7.01], primary motor [left: F(1,32) = 7.09; right: F(1,32) = 7.45], and primary sensory [left: F(1,32) = 9.59; right: F(1,32) = 8.18] cortices during IMG-BWD only.
• The evidence suggests the exercise intervention did not affect gait or BOLD signal during MI.