Exp Brain Res: Muscle coordination in complex movements during jete in skilled ballet dancers.
The principle goal of this study is to gain insight into the coordinative structure of a complex body movement. It analyzes the activity of multiple skeletal muscles associated with the drawing-like movements that resemble jete as performed by skilled ballet dancers. The EMG activity of 18 muscles of the trunk, pelvis, and both legs was recorded when dancers standing on the left leg move the toe of the right leg forward and backward along a straight line. A major finding is that the EMG activity of all right muscles, despite their functional and anatomical diversity, was minimized not only at the initial, vertical position, but also in the reversal phase of movement when the moving leg was maximally deviated from the vertical position. In other words, the activity was minimal when torques of the weights of limb segments were minimal as well as when these torques were maximal. In contrast, in the static task when the maximally deviated leg position was maintained, there was substantial tonic activation of leg muscles, an activity that was necessary to balance these torques. This finding is consistent with the hypothesis that movements of the body result from centrally induced changes in the muscle recruitment thresholds influencing the referent configuration of the body. Furthermore, an immediate consequence of the hypothesis is that, in movements of the limb, the EMG patterns should be a direct-dependent phenomenon known as "directional tuning" of muscles. In combination with the principle of minimal interaction of the neuromuscular system, the referent configuration hypothesis offers a dynamic approach to explaining how control levels may guide multi-muscle and multi-joint systems without redundancy problems.
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|Author:||Lepelley, M.-C.; Thullier, F.; Koral. J.; Lestienne, F.G.|
|Publication:||Journal of Dance Medicine & Science|
|Article Type:||Brief article|
|Date:||Apr 1, 2008|
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