Pesquisadores: Universidades Internacionais
Pesquisadores: Universidades Nacionais e Projetos
Portal Tech4Health: Rede de Conhecimento
tronco, e cabeça durante a marcha de hemiparéticos
Abstract: The aim of this study was to analyze integrally the movement of upper and lower limbs, trunk and head using the following kinematics variables: joint angles, spatiotemporal variables, trajectory of total body center of mass and partial contributions of the segments for the trajectory of total body center of mass. In order to identify and analyze the gait pattern alterations developed by hemiparetic subjects affected by stroke, were analyzed 14 hemiparetics subjects, males, aged between 40 and 60 years old, who presented at least 3 years post-injury, and no walking aids used. To represent the normal gait were selected 7 able-bodies subjects, males, aged between 40 and 60 years old, without gait deviations. The data was obtained by videogrammetry through the DVideo system. The body segments orientation model used on this study consisted in 71 surface markers, whereas 15 articulated body segments. The data processing was done by Matlab software. The statistical analysis was based on the following comparisons: 1) right and left sides of the control group subjects and between the affected and unaffected sides of the hemiparetic group; 2)Comparisons between hemiparetic group and control group; 3) Continuous angle variables comparisons between the affected hemiparetic side versus control group and unaffected hemiparetic side versus control group; 4) Comparisons of the trajectory of total body center of mass and the percent of partial contributions of body segments between control group versus hemiparetic group (P<0.05). The results showed that the affected upper limb movement was significantly altered, with reduced flexion/extension range of motion in the glenohumeral and elbow joints, and it was associated with the elbow joint flexion and rotation tendency throughout the gait cycle. Were also detected significant changes on the three lower limbs movement planes and spatiotemporal variables that agree with the literature findings. The integrated analysis showed changes in stroke gait pattern could be related to the affected upper limb movement disturbances. This is another aggravating factor on the stroke gait pattern. The analysis of the trajectory of total body center of mass showed that the lateral and vertical directions curves of hemiparetic subjects were approximately sinusoidal, with two peaks of different amplitudes, associated with a lower anterior-posterior displacement of the total body center of mass during gait of hemiparetic. The percentual contribution of body segments for the trajectory of total body center of mass showed that the trunk contributed more to the lateral center of mass, and in vertical direction the leg and foot on the affected side contributed more to lower vertical displacement of center of mass. In the lateral direction the lower limbs compensed the upper limbs reduction. reduction. Changes in the direction of progression come from the combination of the disturbances observed in the other two directions.
para análise cinemática na marcha e na corrida
Abstract: The purpose of this study was to compare two protocols for kinematical analysis of sprinters according to velocities, body segments and joint angles during walking and running. The first protocol uses retroreflective markers mounted on fixtures attached to the body segment and the second uses retroreflective markers directly located on the skin surface. Six male athletes were studied during treadmill running at 5 and 20 Km/h and recorded with eight 120 Hz video cameras. A three-dimensional model constituted by fifteen segments represented the sprinters: head, thorax, pelvis, the right and left feet, shanks, thighs, scapulas, arms and forearms. The calibration of the cameras, the synchronization of the registrations and the 3D reconstruction of the coordinates of the markers were done in the Dvideo software. All data were analyzed using Matlab 7.0. The results show that the variability of the length of the segments and of the distances between the markers and the maximum difference maximum between the angles obtained by each protocol were higher with the increase of the velocities, showing that the errors in the analysis of the movement during the running were larger than these ones during the gait. There was no effect of the velocities in the correlation between the angles obtained by each protocol. The variability of the distances between the markers in the lower limb were higher than this one in the upper limbs and the variability of the length of the shank was higher than this one in the other segments. The results also showed a higher correlation was found between the flexion/extension angles (0,99) obtained by each protocol and for each joint, followed by the abduction/adduction angles (0,78) and the angles of internal/external rotation (0,65). The lower values found in the maximum angular difference were between the flexion/extension angles (6,3° ± 3,4°) obtained by each protocol and for each articulation, followed by the abduction/adduction angles (13,2° ± 7,9°) and the angles of internal/external rotation (17,2° ± 8,4°). No differences were found in the variability of the length of the segments and also in the analysis of the angular kinematics, however the adduction/abduction and internal/external rotation angles should be regarded with much more caution.
Abstract: The human gait is a complex movement and its analysis requires a model of the human body based on a system of articulated rigid bodies with several degrees of freedom. Because of the difficulty in obtaining the anthropometric and kinematics variables needed for analysis, it is common in the biomechanics field to use a representative model only involving the inferior limbs of the body and the pelvis. However, the human body is an articulated system, and any alterated movement in one of its parts will affect the global result of the gait. The analysis of the whole human body during such a movement cycle would be of great importance for the understanding of eventual disturbances of the movement during the gait. The aim of this paper is to propose an experimental protocol for gait analysis with orientation of head, trunk, pelvis, superior and inferior members from kinematics and anthropometric variables. This protocol was implemented for the Dvideow system. The orientation and representation model of the corporal segments proposed in this work presents six degrees of freedom for each one of the segments, an important factor for a complete gait analysis, because all the body segments can be analyzed simultaneously, preserving its six degrees of freedom during gait. The quality of the results obtained was evaluated by accuracy tests, kinematics and anthropometric variables, and comparing the joint angles obtained according to protocols proposed in the literature. The agreement in the segmentation of the proposed model for kinematics analysis and the anthropometric model allowed the acquisition of anthropometrics measures concomitantly, reducing the time for the collection of reliable data and easing the imposed conditions for direct measurement. The integration these two types of analysis, kinematics and anthropometric, including the segments like head and superior members, facilitates the interpretation of the movement disturbances. In conclusion, this study developed a protocol to analyze the human gait that integrates the acquisition of kinematics and anthropometric parameters of the whole body, results presented are compatible to findings in the literature, and represents a movement analysis system of low cost. What makes feasible the use of this methodology is a more accurate analysis of normal pathological movements during gait.
Universidade Federal do Rio Grande do Sul
submetidos à estimulação cerebral profunda de alta frequência do núcleo subtalâmico
Abstract: Levodopa has been shown to be efficient in treating Parkinson's disease (PD) in its initial phase. However, as the disease progresses, motor complications, such as abnormalities of the gait, are common. High frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is one of the surgical treatment methods recommended for advanced cases. The aim of the present study was to compare the gait parameters of PD patients under the influence of dopaminergic medication and/or high frequency DBS using the Gait Deviation Index (GDI) and the Gait Profile Score (GPS). Sixteen PD patients were submitted to high frequency DBS of the STN. The gait assessments were applied using the UPDRS (Unified Parkinson's Disease Rating Scale) part III scale in three conditions: without medication and with stimulation; with medication and stimulation; with medication and without stimulation. The gait assessment was conducted using three-dimensional kinematics. The kinematic data was then used to calculate the GDI and GPS. The data were analyzed using the variance for repeated measures test (ANOVA), with the level of statistical significance set at P < 0.05. Statistically significant differences (P < 0.05) were found for the variables UPDRS, GDI, GPS and GVS (Gait Variable Score) (Hip Flx / Ext, Knee Flx / Ext) between the treatment with medication and without stimulation and the other two treatment conditions. In the comparison between treatment without medication and with stimulation and the other two treatment methods, or isolated medication compared to the other two treatment methods together, a high magnitude of effect was observed (Cohen’s ¯d = 0.60 - 1.93) for the variables UPDRS, GPS and GVS (Hip and Knee), whereas a medium magnitude was found for GDI (Cohen’s ¯d = 0.45) bilaterally. The results demonstrated that PD patients recorded greater scores in the UPDRS, GDI and GPS-MAP when the two treatments were applied together.
Universidade Federal do Rio de Janeiro
- Tese de Mestrado Modelagem matemática, simulação e controle artificial da postura em seres humanos
- Tese de Doutorado Modelagem biomecânica e controle ótimo da postura humana através de algoritmos baseados na teoria das aproximações consistentes
Abstract: Neural prostheses and motor control studies may find in computational simulation studies helpful aids. This work, focusing on human postural dynamics and control, looked for developing a series of models that should include: rigid body mechanics, muscular contraction and neural excitation dynamics, and also an associated geometric musculoskeletal modeI. A methodology for controller design was established, using the LQR approach, and the pseudoinverse matrix for distribution of control torques among redundant musculotendon actuators, employing also an inverse model of muscular contraction dynamics. Results shows some effects on simulations for initial conditions, with LQR weight matrix variations. Muscular coordination pattem is dicussed
Abstract: This work presents improvements on a biomechanical model of the human posture developed by the author (Menegaldo, 1997; Menegaldo e Weber, 1998). Several submodelswere analyzed, dealing with multi-body dynamics, muscle mechanics, neuromuscular activation dynamics and lower limb musculotendon geometry. An optimal control methodology developed by Schwartz (1996), based on Polak's Consistent Approximations Theory (Polak, 1996), has been used to find open-loop muscular activations patterns for postural tasks. Optimal cost functions were chosen and tested to solve the optimal control problem, at the same time that the actuator redundancy problem is solved in a physiologically feasible way. The resulting methodology is to be applied, in the future, for numerical simulation of the posture behavior in normal or impaired people who are candidate to orthopedic surgeries procedures.