Abstract Background and aims Dynamic robot-assisted body weight unloading (BWU) presents a novel method to reduce the neuromuscular demands during weightbearing movements by applying a vertical upwards force acting on the body centre of mass. This method may allow severely disabled stroke-affected individuals to complete functional performance-based tests without floor-effects. Thus, the aim of this study was to evaluate the criterion validity of robot-assisted functional assessments against the Fugl-Meyer Lower Extremity Assessment of Motor Function (FM-LE). Methods This cross-sectional study presents baseline data from an ongoing randomised controlled trial RoboRehab (ClinicalTrials.gov: NCT06273475). The 10-meter walking test (10-mwt) and 5-times chair-rise test (5-CRT) were performed with dynamic BWU assistance. Results Sixteen stroke-affected individuals were included (Mean±SD: Age: 76±8, Time since stroke: 15.6±4.4 months, FM-LE: 17.25±8.3, Functional Ambulation Category: 1.5±1.5, knee extensor maximal muscle strength asymmetry 45±25.9%). Ability to complete the tests increased upon the application of BWU from n=3 (19%) and n=2 (12%) to n=15 (94%) and n=14 (87%) to for the 10-mwt and 5-CRT, respectively. A significant correlation was found between the FM-LE and BWU-assisted 10-mwt (r=-0.68, p=0.01), but not between the FM-LE and the BWU-assisted 5-CRT (r=-0.31, p=0.32). Conclusions BWU-assisted tests allowed a larger proportion of the patients to complete the assessments, thereby reducing floor-effects and supporting valid task-specific assessments of motor function for gait in moderate-to-severely disabled stroke-affected individuals. However, further adjustment is needed for the sit-to-stand test to reflect clinical motor impairment as quantified by the FM-LE. Conflict of interest
Jensen et al. (2026) studied this question.