In the last decade or so, the number of research investigations devoted to the study of motor co-ordination has increased considerably, as pointed out in the chapter by Button and Summers in this text. This effort has reflected an increasing desire to understand the mechanisms involved in mastering the redundant degrees of freedom of the neuro-musculo-skeletal system when assembling stable but flexible patterns of co-ordination during goal-directed movements (Bernstein, 1967). For a long time, the theoretical constructs proposed to explain the mechanisms sub-serving movement co-ordination in living systems was built exclusively on the hypothesis of the existence of motor programmes or hardwired central pattern generators (CPG) stored in the nervous system (e.g. Schmidt and Lee, 1999). More recently, the dynamical systems approach has been successfully applied to the task of identifying stable states and transitions in movement co-ordination. To recall from the chapter by Button and Summers, empirical work has shown that the dynamics of the order parameter (e.g. relative phase in many of the tasks of previous work) allows the identification of stable states that constitute the intrinsic co-ordination dynamics of the movement system. These co-ordination tendencies express the preference of an individual to adopt specific movement patterns, rather than others, because these forms are more stable, efficient or functional for the system (see Sparrow, 2000).