Multi-joint coordination in ballet dancers.
In upright posture, we analyzed the multi-joint coordination during drawing ellipses with the foot in a horizontal plane in classical ballet dancers (Elite) and gymnasts who had no dance training (Novice). In both groups, the stability of the head and the trunk was similar. Furthermore, a comparatively simple synergy inter-relating the movements in the hip, knee and ankle joints, was revealed by the kinematic analysis. However, novices made larger errors in the eccentricity and orientation of ellipses than ballet dancers. Ankle angular excursions were smaller in novices than in dancers whereas hip angular excursions were larger. This study illustrates some rules underlying the ability of the nervous system to integrate multiple degrees of freedom of the body to master body balance while producing complex leg movement trajectories. This study offers a dynamical approach of the problem of redundancy.