O efeito do atraso em movimentos reversos do cotovelos : comparação entre sujeitos saudaveis e portadores da doença de Parkinson / The effect of delay on the control of reversal movements of the elbow: comparison between healthy individuals and Parkinson s disease patients

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Within this study were investigated the effects of special conditions like aging and the Parkinson s disease on the control ofreversal movements ofthe elbow joint performed with a variable delay between the two components (Ml and M2) ofreversal. Another aim was to verify if the stretch-shortening cycle exerts his potentiating effects on muscular contraction in this population. To perform these observations, 12 volunteers were recruited. Six of them (3 males and 3 females) were normal at their neurological assessment and were between 51 and 71 years of age (Mean = 62.33 e S.D.= 8.95), and the other six (3 males and 3 females) had been diagnosised with Parkinson disease and were between 59 and 77 years old (Mean = 68.66 e S.D. = 7.47). They executed fast single-joint movements with a reversal, moving towards a target (Ml) and getting back to the initial position (M2). These movements were accomplished in three different distances (20°, 40° and 60°) and between the two components ofreversal (Ml e M2) there were variable delays (Os, 0.2s, 0.5s eIs). The elbow angle was recorded using a optoelectric system of motion analysis (OPTOTRAK@ 3020) and the electrical activity of braquioradialis (BRR) and lateral head of triceps brachi (TR) muscles were recorded by a electromyograph EMG DelSYS (model DE2.2L) with surface electrodes placed over the muscles bellies. The aging did not affect the EMG patterns used by these persons in activating the agonist and antagonist muscles to accomplish single-joint movements with a delay between the movements toward the target and the return to the initial position. The velocity of movements executed by the elder1y volunteers was lower due to the fact that the same strategy applied to young hea1thy persons was used, however with less EMG activity. The volunteers with Parkinson s disease moved slower than the heaIthy elderly and young subjects due to aIterations in the modulation of EMG activity. Altough they kept the triphasic pattern, the EMG showed multiple bursts that aItemated during the task accomplishmen~ which decreased the amount of ellectricaI activity. Besides, they did not reduce the magnitude of second agonist burst in the reversaI movements without delay, what made the reversion harder. FinaIly, it was noticed that the parkinsonians showed less relaxation of his muscles during the intervaI between TI-T4, and started the return movement needing more TR activity to produce the same velocity, when compared to heaIthy persons, which was not the case. Those movements that reverted with no delay showed higher values concerning the second peak ofvelocity, even within the volunteers with Parkinson disease, sustaining the potentianting action of SSC over the triceps muscle. This effect comes from the influence of reflexes (generated by the muscle stretching), as well as the storage of elastic energy in the muscle and tendon in the eccentric phase of SSC, which are released at the movement of returning (concentric phase)

ASSUNTO(S)

electromyography movimentos reversos ciclo de alongamento-encurtamento doença de parkinson reversal movements kinematics cinematica parkinson disease stretch-shortening cycle eletromiografia

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