Effects of load carriage and fatigue on gait coordination and variation in healthy males

Changing the environment or introducing perturbations to the system can lead to a change in segmental coordination. Variability in the coordination of a movement permits exploration of the task, allowing for development of stable coordinative states over time [1]. When significant constraints and/or large enough perturbations are introduced, a shift between these attractor regions allows for an individual to adapt to changes in the motor activity while achieving the same goal [2,3]. Adaptations to small perturbations are dealt with mainly by variation, maintaining the same coordination pattern but temporarily deviating from the theoretical optimal or normal pattern [4]. Too little or too much variability may have implications for injury risk [6]. The relationship between stability and variability allows for individuals to both achieve persistence at completing a task and to change the motor output as needed when perturbations are introduced.