Penguin Waddling Results in Reduced Step Width Variability

Previous research indicates that an increased amount of step width variability in humans is associated with an unstable locomotive pattern. For example, the elderly have an increased amount of step width variability compared to their younger counterparts (Ownings & Grabiner, 2004). This notion is further supported by simulations from passive dynamic walking models. Twodimensional passive dynamic walking models can produce a stable sagittal plane gait pattern based on mechanics alone. However, three-dimensional passive dynamic walking models cannot produce a stable gait and requires additional control in the frontal plane to prevent falls (Kuo, 1999). These scientific observations suggest that the medial-lateral motion of gait must be actively controlled by the nervous system, otherwise falls will occur. Experimental observations indicated that a gait pattern that lacks medial-lateral control will have an increased amount of step width variability (Ownings & Grabiner, 2004). However, it is not currently clear what neuromechancial variables are responsible for controlling the medial-lateral motion of gait.