Meeting Abstract
This talk expands upon the geometrical relationship of force (F) and velocity (V) and its impact on the mechanical power profile of human walking gaits. Utilizing planar ground reaction forces generated from single footfalls; we perform a collision-based analysis that provides the weighted-averages of three descriptive geometries throughout the stride cycle: • Force angle, the direction of F with respect to gravity • Velocity angle, the trajectory of V with respect to the substrate • Collision angle, the deviation from a perpendicular arrangement of instantaneous F and V These averages coarsely describe the analyzed gait and can be used to assess the relative mechanical cost of transport (CoTMECH) between strides and across individuals and populations. In order to clarify that the F and V geometries are indeed responsible for increases in mechanical cost of transport, we parsed the time-varying mechanical power contributions of single- and double-stance phases of the stride. In healthy controls, this analysis revealed that step-to-step (STS) transition mechanical work contribution decreases by 20% across the range of walking speeds. The economy of the mechanical workload throughout the distinct phases of the walking is an important concept in limiting the energetic cost of dynamic motion. The analysis described in this talk allows for a tightened focus on costly walking mechanics that contribute to the CoTMECH assessment for a myriad of walking gait solutions: healthy, pathological, device-assisted, robotic, etc. In addition, this analysis reveals asymmetries between single-stance phases and the STS transitions that flank the center step and would be subject to further exploration or intervention when applied clinically.
