Methods for Analyzing Movement Variability

Variability is a fact of life. Variability is variations that occur in Human performance after multiple repetitions. The central concept of behavioral flexibility in motor control was presented by Bernstein when he stated that movements are a “repetition without repetition” to describe how, well-learned movements, show variation when achieving the task outcome. Handwriting is an example of a complex task that results from a sequence of movements. It has a specific variability structure, and temporal organization, that inform the regularity with which children write as well as their adaptability to the task, e.g., a fractal dynamics behavior. Movement analysis using nonlinear dynamical systems theory for human behavior provides a better understanding of the execution of pathologies, psychomotor problems, or problems in motor control. Dynamic Systems theory suggests that biological systems self-organize according to the environment, and biomechanical and morphological constraints to find the most stable solution for producing a given movement. The concepts of variability and chaotic variation in human movement, along with advanced tools used to measure human movement variability open new perspectives to guide practice and a fundamental complementary means of diagnosis.