THE DYNAMICS OF GAIT TRANSITIONS - EFFECTS OF GRADE AND LOAD

Diedrich and Warren (1995a) proposed that gait transitions behave like bifurcations between attractors, with the relative phase of the leg s egments as an order parameter and stride frequency and stride length a s control parameters. In the present experiments, the authors tested t he prediction that manipulation of the attractor layout, either throug h the addition of load to the ankles or through an increase in the gra de of the treadmill, induces corresponding changes in the walk-run tra nsition. As predicted, the load manipulation shifted the most stable w alk and the transition to lower stride frequencies. In contrast, the g rade manipulation shifted the most stable walk and the transition to s horter stride lengths. Other features of the dynamic theory were also replicated, including enhanced fluctuations of phase and systematic ch anges in stride length and frequency at the transition. Overall, in th ese experiments a shift of the attractors in control parameter space y ielded a corresponding shift of the transition.