Biology subjects

Parmet, Y.

Publications and source records attributed to Parmet, Y..

3 recordsLinked to original sources

bioRxiv2023

The Effect of Arm Restriction on Dynamic Stability and Upper Body Responses to Lateral Loss of Balance During Walking: An Observational Study

When losing balance, upper-body movements serve as mechanical aids to regain stability. However, it remains unclear how these movements contribute to dynamic stability during recovery from a lateral loss of balance while walking with arm restriction. We aimed to 1) quantify the effect of arm restriction on gait stability and upper-body velocities, and 2) characterize upper-body kinematic strategies in response to lateral surface translations under different arm restriction conditions. Healthy adults were exposed to lateral surface translations while walking on a computerized treadmill under three conditions: free arms, 1-arm restricted and, 2-arms restricted. Dynamic stability and upper-body velocities for the first step after perturbation onset were extracted. We found decreased dynamic stability in the sagittal plane and increased trunk velocity in the 2-arm restricted condition compared to the free arms condition. Head and trunk movements in the mediolateral plane were in opposite directions in 44.31% of responses. Additionally, significant trunk velocities were observed in the opposite direction to the perturbation-induced loss of balance. Our results support the contribution of increased upper-body velocities to balance responses following arm-restricted walking perturbations and suggest that the 2-arm restricted condition may be utilized as a perturbation-based balance training, focusing on head and trunk responses.

neuroscience↗

bioRxiv2023

Comparative Analysis of Cameras and Software Tools for Skeleton Tracking

BackgroundSkeleton tracking is a valuable tool for monitoring user performance and has been performed with different sensors and software tools. It enables to quantify 3D motion accurately. We present a comparative analysis of cameras and software tools utilized in skeleton tracking. We describe an experimental design and analysis methods with four steps. Specifically, we conducted an analysis comparing two ZED-2i cameras with a RealSense camera using commercial skeleton tracking algorithms. MethodsThe comparative analysis methodology describes the experimental design and analysis methods for comparing kinematic data from both upper and lower extremities. An experiment to evaluate the performance of three different cameras (RealSense, ZED2mm, and ZED4mm) and three skeleton tracking algorithms (PyZED, Nuitrack, and MediaPipe) was performed with 16 participants. The participants were required to walk along a 6-meter-long path while moving their hands up and down horizontally. Ground truth was measured by a Vicon 3D motion analysis system. Two groups of features corresponding to the upper and lower extremities were derived from the raw data and compared using two methods. In the first method, the RMSE values were compared to the data from the Vicon system. The RMSE results were also combined using two grading techniques with different feature importance weights to determine the camera with the lowest RMSE. In the second method, a linear mix model with a Wald statistical test was applied. ResultsThe ZED-2i cameras outperformed the RealSense camera across upper- and lower-extremity features and different weights. The ZED2mm camera showed better average median grading, lower standard deviation, and superior performance in the model analysis. ConclusionThe comparative analysis methodology provides a systematic method to compare software tools and cameras for skeleton tracking. The ranking enables to prioritize different features. Skeleton tracking with the ZED cameras yielded better performances for both upper and lower extremities features.

bioengineering↗

bioRxiv2020

Downward Gazing for Steadiness

When walking on an uneven surface or complex terrain, humans tend to gaze downward. Previous investigations indicate that visual information can be used for online control of stepping. Behavioral investigations suggest that, during walking, the availability of visual information increases stepping accuracy, but probably through a feedforward control mechanism. Consequently, downward gazing (DWG) is usually interpreted as a strategy used to acquire useful information for online and/or feedforward control of stepping. Visual information is not exclusively used for guiding locomotion; a wealth of literature has been published on the usefulness of visual information for feedback postural control. Critically, postural control has been shown to be sensitive to the visual flow arising from the respective motion of the individual and the 3D environment. To investigate whether DWG can be used to enhance feedback control of posture, rather than feedforward/online control of gait, we conducted a series of experiments that explore this possible interplay. Through these experiments we were able to show that DWG, just a few steps ahead, results in a steadier standing and walking posture, without the need for accuracy. Moreover, we were able to demonstrate that humans resort to DWG when walking stability is compromised, even when destabilizing features were visually unpredictable. This series of experiments provides sufficient evidence of the possible interplay between visual information used for guiding locomotion and that used for postural control. Moreover, this evidence raises concerns regarding the way we interpret gaze behavior without the knowledge of the type and use of the information gathered.

neuroscience↗