Shape and Magnitude of Lower Extremity Kinetics Changed Steps Before Gait Transition During Increasing Speed Induced Walk-to-Run Transition

Introduction and Objectives: Walking and running represents two different steady states in human locomotion. Study walk-to-run gait transition helps us to understand how human movement changes from one steady state to another. The purpose of this study was to investigate lower extremity joint moments and power patterns during gait transitions with continuously increased walking speeds. Methods: Walk-to-run gait transitions were tested with thirteen college aged participants. The gait transitions were induced by increase treadmill speed. Full body reflective markers were captured using eight digital cameras while the participants walked on a force plate embedded treadmill. Inverse dynamics was employed to estimate sagittal plane ankle, knee, and hip joint moments / power for the last five steps before walk to run gait transition. Results: Ensemble curves of joint moments data presented in Figure 1. Horizontal axes represent 100% of a gait cycle. Vertical dotted lines indicate the end of stance phase and the beginning of swing phase. We have used horizontal (or slightly slopped) dotted lines to represent changes of a particular parameter across the five steps before walk-to-run gait transition. Ankle joint moments can be seen at the upper panel of Figure 1, where plantarflesor moments are presented as positive. The most observable changes occurred at the last step before walk-to-run gait transition, where 1) the peak plantarflexor moment increased and happened earlier during the stance phase, along with 2). the disappearance of the dorsal flexor moments which commonly happens at the beginning of the stance phase. There are three knee joint moment peaks can be observed during the stance in the middle panel: extensor peaks at the beginning and end of the stance phase, as well as the flexor peak between the two. The first extensor peak increased slightly during the first four steps displayed here where the other two remain largely unchanged. The first peak in creased to almost twice as observed in the previous steps, with the other two almost disappeared during last step before gait transition. Hip joint moments (lower panel in Figure 1) remained steady for the first four steps presented here. But hip joint flexor moments reduced significantly during the last step before changed to run. Joint power data will not be presented here with the limited spaces allow for this abstract but they do support the same trends observed with the joint moments. Conclusion: We have observed transition specific non-linear joint kinetic behavior in this study. Sagittal plane lower extremity joint moments and joint power changed in shape and magnitudes during the five steps approach walk to run transition, especially the last step before transition. These results indicated that, in preparation for transition, joint kinetic changes steps before gait transition along with increased walking speed