Variability and Stability of Dynamic System Applied to Movement Evaluation

Greater variability is traditional viewed as associated with a decline of sport performance and pathologic problems during locomotion (such as impaired postural and gait control). However, with the development of dynamic system theory in the field of movement science, the above-mentioned concept has been challenged. Recent studies suggested variability during movement was very important both theoretically and clinically. Variability had become an essential evaluation tool by using the dynamic system method to evaluate human movement stability. This paper reviewed the application of the dynamic system theory and method in postural control and gait transition studies. The analysis and quantification of the variability and stability in coordinated movement can 1) help researcher better understanding the relationship between the variability and stability; and 2) provide a theoretical basis for injury prevention and clinical diagnosis of pathological conditions.