ABSTRACT
Frequency locking, intermittent, and non-locking modes of coordination were found, both before and after the speed change, depending on the combination of pendulum length and treadmill speed. This chapter addresses the stability of these modes of coordination between the upper and lower body tasks by changing the treadmill speed while participants perform the task, resulting in discrete shifts in stride frequency. If the coupling between the two tasks is significant, mode of coordination and coupling strength should be stable to this parametric perturbation. It is hypothesize that, although the two rhythms are independent when no locking is present, some dependence will be evident in changes in frequency of the upper body task as the lower body frequency changes. Synchrograms were used to detect the presence of frequency locking. T-tests were used to evaluate whether rhythmic frequencies had changed after the speed change. Coherence and cross-average mutual information measures were used to assess the magnitude of coupling among the four joints.
