EMG activity of upper limb on spinal cord injury individuals during whole-body vibration.

Whole-body vibration (WBV) has shown positive results increasing electromyographic (EMG) activity and strength in a healthy population when applied to upper and lower limbs. The aim of this study was to verify if WBV increases the EMG signal of the upper limb muscles in patients with spinal cord injury (SCI). For this study, 15 patients with SCI were selected and one single session of WBV was applied to the upper limb. Five sessions of 30 s at 30 Hz were applied and EMG of anterior deltoid and forearm muscles was measured. The results show that EMG activity had a significant increase during WBV session compared with baseline muscle activity. These results support WBV as an efficient tool to increase the upper body EMG in individuals with SCI.

Principles for learning horizontal-planar arm movements with reversal.

PURPOSE: This study tested the hypothesis that muscle and interaction torques can be altered independently in order to improve in specific kinematics performance observed following practice. We also tested the hypothesis that a simple set of rules of EMG-control and kinetic-control models could explain the EMG and kinetic changes due to practice of movements with reversal. SCOPE: Kinematics of the upper arm with reversal, performed over three distances, was reconstructed using motion analysis. The muscle and interaction torques were calculated using inverse-dynamics. EMG activities of the major arm muscles were also recorded. The results demonstrate that improved performance is facilitated by an increase in muscle torque (and therefore acceleration) at the proximal joint (shoulder) and by an increase in the interaction torque at the distal joint (elbow). No changes were observed in the amount of muscle activity underlying these kinetic modifications, except for a decrease in the shoulder antagonist latency. CONCLUSION: The results confirm Bernstein's idea that the central nervous system takes advantage of the passive-interactive properties of the moving system. Also the modulation of the EMG patterns should be explained taking in account the reactive forces and the dual functions (maintenance of posture and generation of movement) of the muscles.

Estrategias eletromiograficas e cineticas para o controle motor dos movimentos / Electromyographic and kinetic strategies to control movements

O presente trabalho e uma revisao de literatura sobre as estrategias eletromiograficas e cineticas usadas pelo sistema nervoso central para controlar movimentos voluntarios. Essas estrategias foram identificadas durante a execucao dos movimentos simples e complexos, com e sem reversao em direcao. Objetivo: a proposta desse artigo e discutir o conjunto de regras usadas para modular os padroes de atividade muscular e a forca gerada nas articulacoes (torque muscular). Primeiramente abordamos as estrategias eletromiograficas usadas para controlar movimentos envolvendo uma ou duas articulacoes. Discutimos as estrategias cineticas, em termos de geracao e modulacao do torque muscular para realizar movimentos simples e complexos. A sinergia linear entre atividade muscular e torque muscular ea correlacao entre torque muscular gerado em articulacoes ligadas em cadeia tambem sera discutida. Alem disso, abordamos o papel das forcas de interacao para o controle dos movimentos. Conclusao: a pratica da fisioterapia requer um arcabouco teorico baseado no conhecimento tecnico-cientifico para guia-la. Nesse sentido, as teorias de controle motor sao ferramentas importantes. tais conhecimentos seriam utilizados para entender as adaptacoes e modificacoes que ocorrem nos mecanismos de controle motor devido a uma disfuncao ou doenca

Coupling between muscle activities and muscle torques during horizontal-planar arm movements with direction reversal.

In this study we investigated the hypothesis that the simple set of rules used to explain the modulation of muscle activities during single-joint movements could also be applied for reversal movements of the shoulder and elbow joints. The muscle torques of both joints were characterized by a triphasic impulse. The first impulse of each joint accelerated the limb to the target and was generated by an initial burst of the muscles activated first (primary mover). The second impulse decelerated the limb to the target, reversed movement direction and accelerated the limb back to the initial position, and was generated by an initial burst of the muscles activated second (secondary movers). A third impulse, in each joint, decelerated the limb to the initial position due to the generation of a second burst of the primary movers. The first burst of the primary mover decreased abruptly, and the latency between the activation of the primary and secondary movers varied in proportion with target distances for the elbow, but not for the shoulder muscles. All impulses and bursts increased with target distances and were well coupled. Therefore, as predicted, the bursts of muscle activities were modulated to generate the appropriate level of muscle torque.