Interference of high-heeled shoes in static balance among young women.

The aim of the present study was to assess the effect of the use of high-heeled shoes on static balance in young adult women. Fifty-three women between 18 and 30 years of age and accustomed to wearing high-heeled shoes participated in the study. None of the participants had any orthopedic or neurologic alterations. Static balance was assessed using a force plate. Oscillations from the center of pressure in the mediolateral and anteroposterior directions were measured both when barefoot and when wearing high-heeled shoes [7 centimeters (cm) in height and 1cm in diameter] under the conditions of eyes open and eyes closed. Two-way analysis of variance was employed for the statistical analysis, with the level of significance set at 5% (p<.05). The results revealed statistically significant differences between tests when barefoot and when wearing high-heeled shoes as well as with eyes open and eyes closed (p<.01). With the use of high-heeled shoes, there was a significant increase in mediolateral oscillation with eyes closed (p<.01). The present study demonstrates that the use of seven-cm high heels altered static balance in the healthy young women analyzed, increasing the oscillation of the center of pressure, regardless of visual restriction.

Estratégias para controlar movimentos complexos usando informação proprioceptiva / Strategies to control complex movements using proprioceptive information

Introdução: Nós mostramos que indivíduos neurologicamente normais usam um jogo simples de regras para modular os torques articulares e as atividades musculares durante o desempenho de movimentos complexos que usando informação visual e proprioceptiva. Objetivo: Aqui nós testamos a hipótese que este jogo simples de regras cinéticase EMG é preservado quando os sujeitos tiveram que confiar na informação proprioceptiva da articulação, sem acesso direto para a orientação de espaço da mão (informação visual) para executar movimentos. Métodos: Movimentos do membro superior com reversão sobre três distâncias do alvo foram reconstruídos. Torques do ombro e cotovelo foram calculados usando dinâmica inversa, e também foram registradas atividades EMG dos principais músculos do braço. Resultados: Os sujeitos tiveram que emparelhar específica excursão angular do cotovelo para alcançar o alvo, e a informação sobre o deslocamento de ponta do dedo e posição do alvo não foi provida. A velocidade linear da ponta do dedo, torques articulares e atividade EMG muscular aumentaram com distância do alvo, e os torques articulares e atividades EMG muscular foram acopladas. Conclusão: O uso de informação de proprioceptiva para planejar o movimento não muda as estratégias cinéticas e EMG usadas pelo sistema nervoso central para executar movimentos de braço horizontal-planar com reversão.

Introduction: We have shown that neurologically normal individuais use one simple set of rules to modulate the joint torques and muscle activities during the performance of complex movements using visual and proprioceptive information. Objective: Here, we tested the hypothesis that this sim pie set of EMG and kinetic rules is preserved when the subjects had to rely on proprioceptive information of the joint, without direct access to the spatial orientation of the hand (visual information) to perform movements. Method: Upper arm movements with reversal performed over three target distances were reconstructed. Shoulder and elbow torques were calculated using inverse-dynamics, and EMG activities of the major arm muscles were also recorded. Results: Subjects had to match specific elbow angular excursion to reach the target, and the information about the fingertip displacement and target position was not provided. The fingertip linear speed, joint torques and EMG muscle activities increased with target distance, and the joint torques and EMG muscle activities were well coupled. Conclusion: The use of proprioceptive information to plan the movement does not change the EMG and kinetic strategies used by the central nervous system to perform horizontal planararm movements with reversal.

O movimento e as forças que agem em nosso corpo / Forces acting in our body during movements

Introdução: Muitos esforços têm sido realizados para estimar as forças que atuam em um corpo em movimento e como essas forças são controladas pelo sistema nervoso central (SNC) para gerar movimentos rápidos e precisos. O entendimento dessas forças e como elas são controladas são de fundamental importância para aqueles que trabalham com o movimento humano. Objetivo: Este estudo tem como objetivo esclarecer, de forma didática, conceitos importantes da cinemática e da cinética, conduzindo o leitor da compreensão de princípios simples a aplicação dos mesmos nas equações de movimento. Metodologia: Este trabalho foi elaborado a partir de uma revisão da literatura nas principais bases de dados da área no período de 1967 a 2009. Resultados: Através da dinâmica inversa é possível calcular os torques musculares e de interação gerados nas articulações. Conclusão: A dinâmica inversa, como uma ferramenta da cinética tem dado uma contribuição importante para as áreas de Controle Motor, Fisioterapia e Reabilitação no sentido de descrever o padrão de geração e coordenação das forças que movem as articulações. Essa descrição tem sido feita para uma grande variedade de tarefas motoras e sua aplicabilidade tem sido estendida para pacientes com disfunção motora.

Introduction: Several studies have been done to determine the forces acting at body during movements and how these forces are controlled by central nervous system (CNS) to generate fast and accurate movements. The knowledge of these forces and how they are controlled are important to professionals that work with human movement. Objective: The goal of this study was to explain, in a didactic way, important concepts related to kinematics and kinetics, conducting the reader from the understanding of simple principles to application of these principles in the motion equations. Methods: This study is a literature review including articles published since 1967 on the main databases from the area. Results: Using the dynamics inverse is possible to calculate the muscle and interaction torques generated at joints. Conclusion: The Inverse Dynamics, has a kinetics tool, has contributed with Motor Control, Physical Therapy, and Rehabilitation areas, helping to describe the generation and coordination pattern of the forces which move the joints. This description has been done to several motor tasks and your application has been extended to handicapped patients.

The linear co-variance between joint muscle torques is not a generalized principle.

In 1996, Gottlieb et al. [Gottlieb GL, Song Q, Hong D, Almeida GL, Corcos DM. Coordinating movement at two joints: A principle of linear covariance. J Neurophysiol 1996;75(4):1760-4] identified a linear co-variance between the joint muscle torques generated at two connected joints. The joint muscle torques changed directions and magnitudes in a synchronized and linear fashion and called it the principle of linear co-variance. Here we showed that this principle cannot hold for some class of movements. Neurologically normal subjects performed multijoint movements involving elbow and shoulder with reversal towards three targets in the sagittal plane without any constraints. The movement kinematics was calculated using the X and Y coordinates of the markers positioned over the joints. Inverse dynamics was used to calculate the joint muscle, interaction and net torques. We found that for the class of voluntary movements analyzed, the joint muscle torques of the elbow and the shoulder were not linearly correlated. The same was observed for the interaction torques. But, the net torques at both joints, i.e., the sum of the interaction and the joint muscle torques were linearly correlated. We showed that by decoupling the joint muscle torques, but keeping the net torques linearly correlated, the CNS was able to generate fast and accurate movements with straight fingertip paths. The movement paths were typical of the ones in which the joint muscle torques were linearly correlated.

Controle motor em indivíduos portadores da síndrome de Down / Motor control in individuals with Down syndrome

Este artigo é uma revisão de literatura a respeito das estratégias de controle motor utilizadas por indivíduos portadores da síndrome de Down para realizar movimentos voluntários simples e complexos da extremidade superior. Essas estratégias são comparadas e discutidas com aquelas utilizadas por indivíduos neurologicamente normais. Será abordado também o efeito do treinamento nas estratégias usadas por indivíduos portadores da síndrome de Down e seu impacto no desempenho motor. De um modo geral, a revisão de literatura revelou que indivíduos portadores da síndrome de Down foram capazes de melhorar o desempenho motor em tarefas simples, atingindo um nível de desempenho motor similar àquele observado em indivíduos neurologicamente normais. Com a prática de movimentos mais complexos, indivíduos portadores da síndrome de Down foram capazes de reduzir o tempo na região do alvo. Por outro lado, não conseguiram aumentar a velocidade dos movimentos. As diferenças no desempenho motor entre os dois grupos são debatidas com base nas limitações que indivíduos portadores da síndrome de Down têm em coordenar os torques articulares e incorporar os torques de interação na solução mecânica da tarefa.

This article consists of a literature review related to a motor control strategies used by individuals with Down syndrome to control simple and complex voluntary movements of the upper arm. These strategies are compared and discussed with the ones used by neurologically normal individuals. Also, we present the effect of training on the strategies used by the individuals with Down syndrome and their impact to the movement performance. Overall, this literature review revealed that these individuals improve their motor performance of single-joints movements at the level observed in neurologically normal individuals. However, for more complex movements with reversal in direction, they are able with practice to reduce the time in the vicinities of the target, but could not improve movement speed. These handicaps are debated based on their limitation in coordinate the dynamic joints torques at the joints and incorporate the interaction torque at the mechanical solution.