The Role of Ecological and Complex Gait and Postural Tasks in the Assessment of Subtle Deficits in Parkinson's Disease

Background/Objectives: Postural and gait assessment is essential in the clinical evaluation of people with Parkinson's disease (PwPD). However, conventional clinical assessments may lack the complexity required to uncover subtle deficits, particularly in individuals who compensate well under controlled conditions but struggle in daily life. The aim of this study was to evaluate whether the incorporation of ecologically relevant postural and gait tasks into a controlled experimental environment enhances the detection of subtle motor deficits in PwPD, and to examine the ability of these tasks to distinguish between different levels of disease severity. Methods: Sixteen healthy subjects (HS) and 16 age-matched PwPD, further divided into Mild_PD (n = 9) and Moderate_PD (n = 7), performed a 60 s postural task on different surfaces (ground, medium elastic response, pebbles and root-like) and two walking tasks on ground (10-meter walk test, 10MWT) and on a 4 m mat with medium elastic response (MatWalk), while wearing five inertial measurement units. Postural and spatiotemporal parameters were extracted and statistically analyzed. Results: Postural task analysis revealed limited between-group differences, whereas within-group comparisons identified several significant differences across surfaces in HS and fewer in the PD group. Gait task analysis showed broader impairments, with some parameters differing in both walking tests and others only during the MatWalk when comparing HS and PD. Compliant surface walking was particularly sensitive to subtle gait alterations in Mild_PD. Conclusions: Ecologically relevant walking tasks, especially on compliant surfaces, may complement conventional assessments by revealing subtle gait impairments in PwPD not fully captured by standard clinical tests.