 The research plan is comprised of three phases: technology refinement pilot effort n5, normal subject study n10, and an impaired subject study n20. During the technology refinement phase, we will refine our existing methods for PD-AFO customization and pilot test the PD-AFO accommodation gait training methods and movement control assessment measurements. The normal and impaired subject studies will be used to document PD-AFO use under a strength substitution paradigm normal subject study and a strength enhancement paradigm impaired subject study. 