Fig. 2
From: Is there a trade-off between economy and task goal variability in transfemoral amputee gait?
A Example of \({\mathrm{E}}_{p}\) and \({\mathrm{E}}_{k}\) oscillations are plotted as a function of gait cycle duration. The shaded area indicates the periods of double support. The plot shows an out-of-phase oscillation of kinetic and potential energy, allowing energy exchange to occur between \({\mathrm{E}}_{k}\) and \({\mathrm{E}}_{p}\). B Demonstration the stride and step (prothesis/intact step) period determined in this study. HC is heel contact of intact limb; PHC is heel contact of prosthetic limb. Stride period is determined from HC to the next HC. Prosthetic step is determined from PHC to HC where prosthetic limb leads, intact limb trails, and single support is on the prosthetic limb. Intact step is determined from HC to the PHC where intact limb leads, prosthetic limb trails, and single support is on the intact limb