Charlotte Le Mouel: Role of postural adjustments in motor coordination in humans

I will present my doctoral work, which has led me to develop the following thesis: in humans, improvements in motor coordination rely on the nervous system adjusting the body mechanical properties to the task at hand through postural adjustments. This work combines a modelling, a theoretical, and an experimental approach. In the first part, I present a model which highlights the role of ankle stiffness for standing still despite neural response delays. In the second part, I present a novel theory of postural adjustments for the initiation of movement. According to this theory, during skilful movement initiation, postural adjustments initially accelerate the centre of mass to increase torque for the movement. Finally, I present experimental results which show that, when given enough time, elderly humans are able to adjust the position of their centre of mass to the task at hand. This postural adjustment is however slower in elderly fallers compared to elderly non-fallers. This suggests that motor coordination relies on the rapid adjustment of the body mechanical properties to changing task requirements.