Marker-less motion capture and data processing
turn-to-sit, fatigue
All movement tasks were recorded via a marker-less vision-based motion capture system, i.e. TheCaptury (The Captury GmbH, Saarbrücken, Germany). This system provides reliable motion data [To extract gait parameters from the TUG sequence, we divided it into four distinct segments: stand-up, turn, turn-to-sit, and walking. We took a sliding window approach to identify the transition points between these segments. Specifically, we sought a sequence of frames with a constant increase in hip-height to extract the starting point of standing-up, taking the inverse approach to find the endpoint of the stand-up phase. We determined the start and endpoints of the turn-to-sit segment similarly. The following method was used to detect the turning segment: first we identified the point farthest from the initial sitting position point, which served as the midpoint of the turning segment. Then we examined the frames before this midpoint to identify the point where the body started to rotate away from the walking direction. We analyzed the frames after the midpoint to pinpoint similarly - the point where the body completed the turn and resumed walking in the opposite direction. By cutting out the sit-to-stand, turn, and turn-to-sit movements, we isolated the walking segments, thus enabling us to calculate these gait parameters: step length [cm], average gait speed [cm/s], cadence [steps/min] and proportion of double support phase of a step [double support, %].For the arm-movement test, we referred to the number of contacts per trial, maximum speed [m/s] achieved by one single arm-movement during one trial, and fatigue [%] over 20 s (percentage change in speed from the first to the last repetition) for analysis. We calculated the mean value of left and right hand for further data processing.Each task, that is TUG conditions and arm-movement test, was performed twice and the mean value was calculated for data analysis as the intraclass correlation coefficient for the two trials ranging between 0.782 and 0.955, meaning substantial to almost perfect agreement.